GATA3: a multispecific but potentially useful marker in surgical pathology: a systematic analysis of 2500 epithelial and nonepithelial tumors. Am J Surg Pathol. 2014;38:13-22. [PMID: 24145643 DOI: 10.1097/pas.0b013e3182a0218f]

Clinicopathological features analysis of Paraganglioma of urinary bladder: A retrospective study

Paraganglioma of urinary bladder (PUB) is a rare neuroendocrine neoplasm. This study is a retrospective analysis of clinicopathological features in 11 cases of PUB. The studied cohort included seven male and four female patients with a median age of 64 years (range 37-73 years). The maximum tumor diameter ranged from 1 to 4 cm (median: 2.5 cm). Macroscopically, most lesions appeared as smooth, polypoid intraluminal protrusions; one case exhibited a nodular mass extending into the outer bladder wall. Microscopic evaluation demonstrated tumor infiltration into the muscularis propria (6 cases) or both lamina propria and muscularis propria (5 cases). Tumor cells were arranged in nested (Zellballen) or organoid patterns. Tumor cells uniformly expressed CD56, synaptophysin, and chromogranin. The Ki-67 proliferation index was ≤8 % in 10 cases; one case with a 4 cm tumor demonstrated a higher Ki-67 index (20 %), correlating with infiltrative growth and increased mitotic activity. Among the 10 cases that were evaluated, 2 (20 %) showed a loss of SDHB expression; Eight (80 %) of 10 cases were GATA3-positive, and all cases were negative for OCT3/4. Nine (81.8 %) underwent transurethral resection of bladder tumor, and 2 (18.2 %) underwent partial cystectomy. Intraoperative blood pressure fluctuations were observed in 2 patients (18.2 %). The median follow-up time was 26 months (range 4-73 months); one patient experienced a recurrence of endometrial cancer 4 years later and was lost to follow-up at 73 months; the remaining 10 patients survived without recurrence or metastasis. Improved preoperative recognition of PUBs relies on integrating clinical, biochemical, and imaging findings. Standardized immunohistochemical panels may enhance diagnostic accuracy.

GATA3 Expression in Solid Vimentin-Negative Eosinophilic Renal Epithelial Tumors-A Comprehensive Study of 48 Tumors

Vimentin-negative solid eosinophilic renal tumors, such as renal oncocytoma, chromophobe renal cell carcinoma (chromophobe RCC), low-grade oncocytic tumor (LOT) of the kidney, and eosinophilic vacuolated tumor (EVT), often present diagnostic challenge to pathologists as they can have significant morphologic overlap. Recent studies have shown that the LOT is consistently positive for GATA3. To test the utility of GATA3 in this potentially challenging diagnostic setting, we investigated GATA3 expression in 48 vimentin-negative solid eosinophilic renal tumors with unequivocal diagnosis, which included 19 LOTs, 3 EVTs, 12 chromophobe RCCs, 11 renal oncocytomas (ROs), and 3 FLCN-mutated renal tumors. GATA3 was at least focally positive in 89% of the LOTs (17/19), 67% of the EVTs (2/3), and 33% of the chromophobe RCCs (4/12) and was negative in all ROs (0/11) and FLCN-mutated renal tumors (0/3). Our study shows that GATA3 can be useful in differentiating between LOT and RO, but it can be focally positive in many tumors of EVT and chromophobe RCC. Therefore, GATA3 could be useful as a panel of immunohistochemical stains that are used in diagnostic algorithm of vimentin-negative solid eosinophilic renal tumors. However, one should not solely rely on GATA3 as vimentin-negative solid eosinophilic renal tumors can have overlapping GATA3 expression.

Extra-Axial Poorly Differentiated Chordoma Initially Misdiagnosed as Epithelioid Sarcoma

Poorly differentiated chordoma is an exceedingly rare, aggressive subtype of chordoma. These tumors typically arise in the axial skeleton of young patients, most commonly the skull base, followed by the cervical spine. Herein, we present a 60-year-old patient with longstanding knee pain and nondiagnostic imaging, initially thought to be due to osteoarthritis. No discrete mass-forming lesion was identified by radiology. Synovial histology at the time of arthroplasty revealed a multinodular proliferation of epithelioid-to-histiocytoid cells with a moderate amount of eosinophilic-to-clear, vacuolated cytoplasm. Scattered cells with high-grade nuclear atypia were present. A diagnosis of metastatic carcinoma was considered due to immunohistochemical positivity for keratin and GATA3. However, a diagnosis of epithelioid sarcoma was rendered based on clinical context, morphology, and loss of immunohistochemical expression for SMARCB1 (INI1). However, upon re-review of the tumor, brachyury was retrospectively added to the immunohistochemistry panel and showed strong positivity, thus prompting amendment of the initial diagnosis of epithelioid sarcoma to extra-axial poorly differentiated chordoma. Given the rarity of this diagnosis, molecular testing was performed which revealed a unique SMARCB1 molecular profile with a single-nucleotide variant in addition to the commonly reported loss of chromosome 22q. This report of an ultra-rare sarcoma in an uncommon anatomic site highlights multiple potential pitfalls in the diagnosis of poorly differentiated chordoma, emphasizes the importance of brachyury immunohistochemistry in rendering a correct interpretation, and underscores an opportunity for further molecular analysis to better define the molecular profile of this entity.

TRPS1 is a useful marker in differentiating metastatic breast carcinoma from pancreatic adenocarcinoma in fine-needle aspiration specimens

OBJECTIVES

Distinction of metastatic breast carcinoma (BC) to the pancreas from primary pancreatic adenocarcinoma (PAC) is essential but challenging. Breast carcinoma shares similar morphology and exhibits an overlapping immunohistochemistry (IHC) profile with PAC. We investigated the utility of recently reported trichorhinophalangeal syndrome type 1 (TRPS1) IHC in differentiating metastatic BC from PAC in fine-needle aspiration (FNA) specimens.

METHODS

We assessed consecutive patients of PAC (n = 49). Due to limited cases of metastatic BC to the pancreas (n = 3), cases of metastatic BC (n = 23) in various locations, including lymph node, lung, bone, or soft tissue, were included. Immunohistochemistry for TRPS1 was performed by using the cell blocks obtained from FNA. A quantitative score for TRPS1 expression was calculated by multiplying the intensity and the percentage of positive cells. Immunoreactivity scores were assigned as negative, low positive, intermediate positive, or high positive.

RESULTS

In 49 PAC cases, 47 (95.9%) exhibited negative while 2 (4.1%) exhibited low positive TRPS1 expression. However, TRPS1 expression was high positive in 23 (88.0%) of 26 metastatic BC cases, including 10 (83.3%) of 12 triple-negative BC (TNBC) and 13 (92.9%) of 14 non-TNBC cases.

CONCLUSIONS

Our results suggest that TRPS1 IHC represents a highly accurate and reliable method for differentiating metastatic BC from PAC.

Metaplastic carcinoma of the breast mimicking breast implant-associated squamous cell carcinoma: a challenging differential diagnosis

Metaplastic carcinoma of the breast (MBC) is an uncommon disease that accounts for 0.2-1% of all invasive breast carcinomas, comprising a heterogeneous group of diseases characterized by differentiation of the neoplastic epithelium to squamous cells and/or mesenchymal-looking elements. Breast implant-associated squamous cell carcinoma (BIA-SCC) is a rare complication of breast implantation, with 22 cases reported in the literature. Due to the histological overlap between MBC and BIA-SCC, the differential diagnosis may be challenging, especially in patients with an advanced cancer-bearing breast implant, in which assessing the tumor's primary site may be difficult. The limited amount of scientific data on BIA-SCC implies the absence of a standardized diagnostic method and of a specific staging system to guide patients' clinical management. Of the 22 BIA-SCC cases reported in the literature, 14 (64%) had squamous metaplasia of the inner surface of the capsule, whereas in 10 (45%), there was a histologically proven spread to the extracapsular tissues without a detailed description of the capsule infiltration. Herein, we describe the case of a peri-implant tumor mass with squamous histology in a patient treated with mastectomy and implant-based breast reconstruction for a microinvasive breast carcinoma, in which the absence of squamous metaplasia of the capsule and of its neoplastic infiltration favored a diagnosis of MBC likely originating from the peri-implant tissue. This case suggests that in patients with peri-implant cancers with squamous differentiation, the extension of the tumor throughout the capsule thickness and the presence of squamous metaplasia of the capsule are critical factors that should be considered in the differential diagnosis between BIA-SCC and MBC. In addition, even in cases with capsule-confined tumors, the depth of the capsular involvement can be used to stage the disease, similar to what is currently recommended for BIA-ALCL.

TRPS1 expression in breast angiosarcoma

Angiosarcoma (AS) of the breast, a rare mesenchymal neoplasm, exhibits distinct forms based on etiological and genetic features. While cases with typical clinical presentation and morphology allow for a straightforward diagnosis, challenges arise when clinical data are scarce, diagnostic material is limited, or morphological characteristics overlap with other tumors, including undifferentiated carcinomas. The trichorhinophalangeal syndrome protein 1 (TRPS1), once regarded as highly specific for breast carcinomas, now faces doubts regarding its reliability. This study explores TRPS1 expression in breast AS. Our investigation revealed that 60% of AS cases displayed TRPS1 labeling, contrasting with the 40% lacking expression. Scoring by four independent readers established a consensus, designating 12/35 ASs as unequivocally TRPS1-positive. However, uncertainty surrounded nine further cases due to a lack of reader agreement (being substantial as reflected by a kappa value of 0.76). These findings challenge the perceived specificity of TRPS1, shedding light on its presence in a noteworthy proportion of breast ASs. Consequently, the study underscores the importance of a comprehensive approach in evaluating breast ASs and expands the range of entities within the differential diagnosis associated with TRPS1 labeling.

Evaluation of breast-specific marker expression in metastatic breast cancers: Correlation with subtype switch

AIMS

This study evaluates the utility of breast specific markers in identifying breast cancer subtypes within metastatic settings. The subtype alteration in metastatic disease and its consequent impact on breast-specific marker expression is also examined.

MATERIALS AND METHODS

GATA-binding protein 3 (GATA3), mammaglobin (MMG), transcriptional repressor GATA binding 1 (TRSP1) and SRY-box transcription factor 10 (SOX10) expression were assessed in a large cohort of metastatic breast cancer (MBC) cases and correlated with the characteristics of both MBC and primary breast cancer (PBC).

RESULTS

GATA3 was the most sensitive in MBC (83.1%), followed by TRPS1 (77.0%), MMG (58.5%) and SOX10 (7.1%). This trend was consistent in hormonal receptor (HR)+ and HR- MBC. Combining GATA3/TRPS1 yielded the highest detection rates in the overall cohort (90.1%) and HR+ MBC (97.1%), while TRSP1/MMG was most effective in HR- (76.2%) and TN (71.1%) MBC. Marker expression did not correlate with metastatic site, except SOX10 in lung metastases (P = 0.031). Subtype discordance between MBC and PBC occurred in 43 cases (24.4%), with GATA3 expression in HR- MBC significantly linked to subtype discordance (P = 0.005). Conversely, SOX10 expression was significantly associated with subtype concordance in HR- and TNBC (P ≤ 0.003). Despite a higher expression of GATA3 in all HR- cases, TRSP1 outperformed GATA3 in detecting concordant HR- cases (64.0% versus 38.5%). TRPS1 and SOX10 were expressed in more than 50% of concordant TNBC cases.

CONCLUSIONS

The expression of breast-specific markers is mainly determined by the PBC subtype. GATA3 retains high sensitivity in HR+ cancers, even after HR loss during metastasis. TRPS1 and SOX10 are identified as valuable markers in TNBC metastasis.

Trichorhinophalangeal syndrome type 1 (TRPS1) in breast pathology: diagnostic utility and pitfalls

INTRODUCTION

Breast cancer, especially triple-negative breast cancer (TNBC), lacks sensitive and specific diagnostic markers that can reliably differentiate it from carcinomas of other origins. TRPS1 is a relatively new immunohistochemical (IHC) marker that has demonstrated higher sensitivity in breast cancer, including TNBC. However, with the increasing use of this marker, broader immunoreactivity has been observed. This study aims to evaluate the utility of TRPS1 for establishing carcinoma of mammary origin. We compared the diagnostic sensitivity and specificity of TRPS1 with that of other IHC markers (GATA3 and SOX10).

METHODS

In this retrospective study, we reviewed TRPS1 IHC performed at our center between 07/2022 and 06/2024, to evaluate the expression of TRPS1 in breast carcinoma (primary and distant metastasis) and in other malignancies. The sensitivity and specificity of TRPS1 in determining carcinoma of breast origin were compared with those of GATA3 and SOX10.

RESULTS

The study cohort comprised 106 cases, including 17 cases at the primary site, and 89 samples of distant metastasis. After correlation with morphology, immunophenotype and molecular studies, 94 cases (88.7%) were characterized as breast primary (37.9% ER+/HER2neu-, 4.6% ER-/HER2neu+, 1.1% ER+/HER2neu+, 56.3% TNBC), whereas 12 (11.3%) were non-breast primary. The non-breast primary sites included lung, bladder, Mullerian, and gastrointestinal. The sensitivity and specificity of TRPS1 were 93.6% and 58.3%, respectively. Conversely, GATA3 demonstrated a sensitivity and specificity of 76.9% and 66.7%, respectively. SOX10 exhibited the lowest sensitivity at 47.9%, but with the highest specificity at 100%. There were three cases of metastatic breast carcinoma (sites: bladder, lung, and bone), where TRPS1 was the only positive marker, whereas GATA3 and SOX10 were negative. TRPS1 showed a higher positivity rate (92.0%) in TNBC compared to GATA3 (63.4%) and SOX10 (56.7%). TRPS1 expression was also observed in other tumor types, including carcinoma of Mullerian origin, bladder, and lung, limiting its utility in the differential diagnosis.

CONCLUSION

Our study demonstrated a higher sensitivity of TRPS1 expression in establishing carcinoma of breast origin compared with GATA3 and SOX10, consistent with previous reported studies. However, the specificity of TRPS1 was lower than that of GATA3 and SOX10. These findings suggest that while TRPS1 can be used as a reliable marker for breast cancer, its expression in other tumor types should be carefully interpreted to avoid diagnostic pitfalls.

GATA4 is diagnostically useful for distinguishing primary ovarian mucinous carcinomas from metastatic colorectal adenocarcinomas to the ovary

AIM

Determining the primary origin of an ovarian mucin-producing carcinoma can be challenging at times because some metastases of primary colorectal origin may exhibit gross, microscopic, and/or immunohistochemical features that overlap with those of primary ovarian mucinous carcinomas (OMCs). We hypothesized that GATA binding protein 4 (GATA4) might be a novel, useful marker for differentiating primary OMCs from metastatic colorectal adenocarcinomas to the ovary.

METHODOLOGY

For comparison with the usefulness of other markers (special AT-rich sequence-binding protein 2 (SATB2) and caudal type homeobox 2 (CDX2)), we elucidated the expression profiles of GATA4 in OMCs, colorectal non-mucinous adenocarcinomas (CNMACs), and colorectal mucinous adenocarcinomas (CMACs) using immunohistochemistry.

RESULTS

We confirmed GATA4 expression (H-score ≥50 points) in 93%, SATB2 in 0%, and CDX2 in 64% of 14 OMCs. GATA4 was expressed in 13%, SATB2 in 90%, and CDX2 in 93% of 30 CNMACs. GATA4 was expressed in 20%, SATB2 in 73%, and CDX2 in 100% of 30 CMACs.

CONCLUSION

The expression of GATA4 in a mucus-producing ovarian tumor strongly supports it being a primary OMC rather than a metastatic colorectal carcinoma: GATA4 expression indicates OMC and SATB2 expression indicates colorectal adenocarcinoma. However, three cases of colorectal adenocarcinoma were GATA4-positive and SATB2-negative, so the GATA4/SATB2 marker combination is not absolute for determining the primary site. Further research for more markers is necessary to find the ideal combination.

Diagnostic Challenges in the Pathological Approach to Pleural Mesothelioma

Malignant pleural mesothelioma (MPM) still represents a complex diagnostic challenge for pathologists in routine practice. This diagnosis requires a multidisciplinary approach, and pathological evaluation is mandatory. The histopathological diagnosis is stepwise and should be based on morphological and immunohistochemical assessment, sometimes associated with molecular tests, and supported by clinical and radiological findings. A correct morphological approach aims to exclude pleural metastasis or benign mesothelial proliferations, which are the main differential diagnoses. While certain histological features are diagnostic of MPM, others are highly suggestive but not definitive. Immunohistochemistry plays a pivotal role, with a panel of both traditional and newer markers being used to assess mesothelial differentiation and to differentiate malignant from benign proliferations. In more challenging cases, molecular tests, such as fluorescent in situ hybridization (FISH) to detect CDKN2A deletion, can be helpful in distinguishing malignant from benign pleural lesions. This review summarizes the key morphological, immunohistochemical, and molecular features that should be considered when pleural biopsy samples are examined, with the aim of improving diagnostic accuracy in this complex area.

Chromophobe Renal Cell Carcinoma With Extensive Retraction Artifact: A Potential Diagnostic Pitfall From Micropapillary Urothelial Carcinoma

In addition to "classic" and eosinophilic subtype, chromophobe renal cell carcinoma (RCC) is well-known to demonstrate various morphological patterns including adenomatoid, microcystic, pigmented, multicystic, papillary, neuroendocrine-like, and small cell-like, all of which are important to appreciate for accurate diagnosis. Herein, we expand on a unique chromophobe RCC morphology not previously described consisting of tumor cells with extensive stromal retraction, mimicking upper urothelial tract micropapillary carcinoma (MPC). Twelve MPC-like chromophobe RCC nephrectomies were reviewed with clinicopathological features recorded; molecular testing was performed on 7 of 12 tumors. Patients were mostly men (n=10) with a mean age of 65 years. Mean tumor size was 6.4 cm with pathological stage distribution as follows: 4 (33%) T1a, 2 (17%) T1b, 1 (8%) T2b, and 3 (25%) T3a. The extent of MPC-like chromophobe RCC foci ranged from 10% to 40% (mean=26%; there was no correlation between the extent of MPC-like chromophobe RCC foci and tumor stage). Other chromophobe RCC morphological patterns were not identified. When performed, all (100%) tumors depicted prototypic chromophobe RCC staining pattern of KIT positivity/KRT7 positivity. Molecular showed 6 of 7 (86%) with multiple chromosomal losses. Clinically significant mutations were identified in NF1, TP53, FLCN (likely somatic), CHEK2, and ZFHX3 genes. Follow up available in 9 patients showed no evidence of disease (mean=23 months). Although the etiology behind the extensive stromal retraction in our tumors is unknown, this may likely be artifactual in nature. Nonetheless, it is important to include MPC-like chromophobe RCC in the spectrum of "variant" morphologies to avoid diagnostic pitfalls from micropapillary carcinoma.

GATA3 Expression in Prostatic Adenosquamous Carcinoma: A Potential Diagnostic Pitfall

Urothelial carcinoma and prostatic adenocarcinoma can have overlapping histologic features and in some instances pose challenges to pathologists. GATA binding protein 3 (GATA3) immunohistochemistry (IHC) is a well-established tool to aid in this specific diagnostic dilemma as it has been shown to be a sensitive marker for urothelial carcinoma and a putatively specific marker in excluding prostatic adenocarcinoma. However, in encountering an index tumor of prostatic adenosquamous carcinoma positive for GATA3, herein we sought to investigate this potential diagnostic pitfall in a larger series of tumors. In this study, we retrospectively reviewed prostatic adenosquamous carcinomas diagnosed in 17 patients across the authors' institutions and personal consult collections in the past 10 years. GATA3 IHC was either reviewed or performed on tumors not previously tested. We also recorded other immunostains that were performed at initial diagnosis. Positivity for GATA3 was found in 9 of 17 (53%) tumors, all within squamous regions (2 tumors also showed concomitant moderate GATA3 positivity within glandular elements). The GATA3 positive tumors were all positive for p63 in the 7 tumors where p63 was also performed. Of all tumors tested, NKX3.1 was positive in 100% (13/13) of the glandular elements (3 tumors also showed NKX3.1 concomitant positivity within squamous regions). In summary, when encountering a carcinoma with mixed glandular/squamous features in which prostatic origin is being considered, awareness of GATA3 immunoreactivity in a subset of prostatic adenosquamous carcinoma is critical to avoid diagnostic pitfalls.

Roles of Post-Translational Modifications of Transcription Factors Involved in Breast Cancer Hypoxia

BC is the most commonly diagnosed cancer and the second leading cause of cancer death among women worldwide. Cellular stress is a condition that leads to disrupted homeostasis by extrinsic and intrinsic factors. Among other stressors, hypoxia is a driving force for breast cancer (BC) progression and a general hallmark of solid tumors. Thus, intratumoral hypoxia is an important determinant of invasion, metastasis, treatment failure, prognosis, and patient mortality. Acquisition of the epithelial-mesenchymal transition (EMT) phenotype is also a consequence of tumor hypoxia. The cellular response to hypoxia is mainly regulated by the hypoxia signaling pathway, governed by hypoxia-inducible factors (HIFs), mainly HIF1α. HIFs are a family of transcription factors (TFs), which induce the expression of target genes involved in cell survival and proliferation, metabolic reprogramming, angiogenesis, resisting apoptosis, invasion, and metastasis. HIF1α cooperates with a large number of other TFs. In this review, we focused on the crosstalk and cooperation between HIF1α and other TFs involved in the cellular response to hypoxia in BC. We identified a cluster of TFs, proposed as the HIF1α-TF interactome, that orchestrates the transcription of target genes involved in hypoxia, due to their post-translational modifications (PTMs), including phosphorylation/dephosphorylation, ubiquitination/deubiquitination, SUMOylation, hydroxylation, acetylation, S-nitrosylation, and palmitoylation. PTMs of these HIF1α-related TFs drive their stability and activity, degradation and turnover, and the bidirectional translocation between the cytoplasm or plasma membrane and nucleus of BC cells, as well as the transcription/activation of proteins encoded by oncogenes or inactivation of tumor suppressor target genes. Consequently, PTMs of TFs in the HIF1α interactome are crucial regulatory mechanisms that drive the cellular response to oxygen deprivation in BC cells.

Role of Immunocytochemistry in the Cytological Diagnosis of Mesothelioma

BACKGROUND

Mesothelioma is an aggressive malignancy of the serosal surfaces with very poor prognosis. It traditionally manifests in older patients and at an advanced stage which results in minimal improvement in prognosis despite the recent advances in management. Early detection would therefore significantly impact management and potentially improve survival. Mesothelioma frequently presents with recurrent effusions, posing cytology as the initial procedure in the workup. A definitive diagnosis would not only spare the patients additional diagnostic procedures but also potentially afford them an opportunity for early surgical intervention and therapy.

SUMMARY

In this article, we review the role of immunocytochemistry (ICC) in the workup of mesothelioma. The various ICC markers to confirm or rule out mesothelial lineage are reviewed. In addition, newly introduced molecular surrogates that confirm the malignant nature of the mesothelial cells and support a definitive diagnosis of mesothelioma are discussed. We also briefly discuss the theranostic implications of such markers and potential impact of such recent advances on the cytological diagnosis and reporting of mesothelioma.

KEY MESSAGES

The cytological diagnosis of mesothelioma no longer requires the extensive expertise in morphological analysis and can be offered based on supporting ICC that confirms the mesothelial lineage and malignant nature of the cells.

Validation of Keratin 17 as a tissue biomarker in the diagnosis of upper tract urothelial carcinoma

Upper tract urothelial carcinoma (UTUC) has a relatively low incidence but presents significant surveillance and treatment challenges. Therefore, novel biomarkers for the accurate detection of upper tract urothelial tumors are urgently needed. We evaluated the expression of Keratin 17 (KRT17), an oncoprotein implicated in the cell cycle progression of multiple human cancers and previously studied in bladder urothelial carcinoma, by immunohistochemistry in 139 UTUC cases, including noninvasive, invasive papillary urothelial carcinoma and urothelial carcinoma in situ. KRT17 expression pattern (basal/negative vs. nonbasal) and H-score were evaluated. The expression pattern was significantly different in normal (NL) compared to malignant urothelium. Nonbasal KRT17 expression was significantly higher in pTa (p < 0.001) and invasive (pTinv) (p = 0.0023) urothelial carcinoma compared to NL, and in pTinv compared to pTa (p = 0.0391). Sensitivity and specificity for distinguishing benign from malignant tumors were 85% and 82, respectively, with an area under the curve of 0.83 (p < 0.001). The KRT17 H-score was significantly higher in pTa and pTinv compared to NL (p < 0.001 and p = 0.0035, respectively). Sensitivity and specificity for distinguishing benign from malignant carcinoma were 91% and 69%, respectively, with an AUC of 0.81 (p = 0.0010). KRT17 was not associated with tumor site, grade, or stage. In summary, K17 is a sensitive and specific marker of neoplastic upper tract urothelium, and its potential use in routine diagnostics should be explored in larger studies.

The Molecular Classification of Pheochromocytomas and Paragangliomas: Discovering the Genomic and Immune Landscape of Metastatic Disease

Pheochromocytomas (PCCs) and paragangliomas (PGLs, together PPGLs) are the most hereditary tumors known. PPGLs were considered benign, but the fourth edition of the World Health Organisation (WHO) classification redefined all PPGLs as malignant neoplasms with variable metastatic potential. The metastatic rate differs based on histopathology, genetic background, size, and location of the tumor. The challenge in predicting metastatic disease lies in the absence of a clear genotype-phenotype correlation among the more than 20 identified genetic driver variants. Recent advances in molecular clustering based on underlying genetic alterations have paved the way for improved cluster-specific personalized treatments. However, despite some clusters demonstrating a higher propensity for metastatic disease, cluster-specific therapies have not yet been widely adopted in clinical practice. Comprehensive genomic profiling and transcriptomic analyses of large PPGL cohorts have identified potential new biomarkers that may influence metastatic potential. It appears that no single biomarker alone can reliably predict metastatic risk; instead, a combination of these biomarkers may be necessary to develop an effective prediction model for metastatic disease. This review evaluates current guidelines and recent genomic and transcriptomic findings, with the aim of accurately identifying novel biomarkers that could contribute to a predictive model for mPPGLs, thereby enhancing patient care and outcomes.

Olfactory Neuroblastoma and Olfactory Carcinoma: A Practical Review

In the sinonasal tract, two tumor types are defined by neuroectodermal differentiation. Olfactory neuroblastoma (ONB), the traditional member of this category, is a keratin-negative neuroectodermal neoplasm that has lobulated architecture and variable neurofibrillary matrix. Olfactory carcinoma (OC), a newly-recognized diagnosis in the sinonasal tract, has keratin-positive neuroectodermal elements frequently intermixed with well-formed glands. These two neuroectodermal entities can show substantial overlap with other sinonasal small round blue cell tumors that express neuroendocrine markers. This review provides a practical overview of the key clinical and diagnostic features of ONB and OC and their differential diagnosis.

FOXO3 induces TUG1-mediated miR-375/GATA3 signaling axis to promote the survival of melanocytes in vitiligo

Vitiligo is characterized by the depletion of melanocytes due to the activation of CD8+ T cells. Taurine-upregulated gene 1 (TUG1), a long noncoding RNA, is involved in melanogenesis. This study aimed to explore the role and mechanism of TUG1 in vitiligo. RT-qPCR and western blot analyses demonstrated decreased TUG1 levels and increased miR-375 levels in patients with vitiligo. MTT and transwell assays indicated that TUG1 upregulation facilitated melanocyte survival and inhibited CD8+ T cell migration. Dual luciferase reporter and chromatin immunoprecipitation assays verified that Forkhead box O3 (FOXO3) directly interacted with the TUG1 promoter, leading to the positive regulation of TUG1 expression. In addition, FOXO3 promoted melanocyte survival by enhancing the transcription of TUG1. Luciferase reporter assay and RNA immunoprecipitation assay confirmed that TUG1 upregulated GATA binding protein 3 (GATA3) expression by targeting miR-375. TUG1 facilitated melanocyte survival by regulating the miR-375/GATA3 axis. In vitiligo, melanocyte survival is promoted by the induction of the TUG1-mediated miR-375/GATA3 axis by FOXO3, which offers new therapeutic targets for vitiligo treatment.

A case of ovarian mesothelioma with VHL mutation diagnosed by immunohistochemistry and literature review

The malignant mesothelioma mainly develops in the pleura and peritoneum, while primary ovarian mesothelioma is very rare. Here, we report the first case of primary ovarian mesothelioma (clear cell variant) with VHL mutations in the world based on the results of histomorphology, immunohistochemistry, and genetic testing. This is an extremely rare type of tumor that has not been reported so far. Through the literature search, we reviewed primary ovarian mesothelioma, focusing on its differential diagnosis and molecular genetics. The purpose of this paper is to deepen the flexible selection and application of immunohistochemical markers in mesothelioma, so as to reduce missed diagnosis and misdiagnosis.

Epithelioid trophoblastic tumor in male patients with germ cell tumor: A clinicopathologic analysis of five cases

Epithelioid trophoblastic tumor (ETT) is an extremely rare chorionic-type neoplasm in the testis, with only seven cases reported in the literature. Here, we report five cases of testicular ETT from a single institution, constituting the largest series of this rare tumor to date. The patients had a mean age of 44 years (range, 20-68 years). Four patients had a previous history of testicular germ cell tumor (GCT) treated with chemotherapy, and they developed ETT in metastatic sites in a mean of 11 years (range, 3-15 years) after the initial diagnosis of testicular GCT. Only one patient had ETT in the testis. Three patients had a normal serum beta-human chorionic gonadotropin (β-hCG) level, and two patients had a level that was slightly elevated, but far below that typically seen in patients with choriocarcinoma. ETT was characterized by a proliferation of intermediate trophoblastic cells with abundant eosinophilic cytoplasm, and the tumors frequently had coagulative necrosis with eosinophilic debris, mimicking keratinizing squamous cell carcinoma. The trophoblastic phenotype of ETT was supported by its immunoreactivity for trophoblastic markers, including GATA-3 (3 of 3 cases tested), α-inhibin (3/4), p63 (3/5), and β-hCG (3/4). ETT was also positive for cytokeratin (4/4) and GCT marker SALL4 (3/3). Despite surgery and chemotherapy, two patients died of disease 17 months after ETT diagnosis, and three patients were alive with metastatic disease at a mean of 20 months (range, 15-28 months). Our results demonstrate that ETT may be an aggressive disease associated with distinct pathologic features and poor clinical outcome.

Primary ductal adenocarcinoma of the lacrimal gland with sarcomatoid differentiation: case report and genomic analysis

We describe a case of primary ductal adenocarcinoma of the lacrimal gland with novel histopathological characteristics corresponding to a biphasic growth course and provide a comprehensive genomic profile of this malignancy. A 39-year-old male with a history of slowly progressive unilateral proptosis and hypoglobus presented after 1 month of hyperacute exacerbation. Orbital imaging revealed a superior mass with osseous erosion. The patient underwent orbital exploration and excisional biopsy via lateral orbitotomy. Histopathology demonstrated high-grade adenocarcinoma with a well-differentiated glandular component alongside a poorly differentiated sarcomatoid region. The glandular section was immunopositive for Her-2, CK7, GATA3, and androgen receptor. Tumor recurrence necessitated en-bloc exenteration with dural resection alongside adjuvant radiotherapy and chemotherapy. This represents the first report of sarcomatoid differentiation in primary ductal adenocarcinoma of the lacrimal gland, which may incite hyperacute progression. Conversely, GATA3 immunopositivity may correlate with indolent growth. Genomic variants such as SEMA3C represent potential therapeutic targets for this condition.

Management of intrahepatic and perihilar cholangiocarcinomas: Guidelines of the French Association for the Study of the Liver (AFEF)

Intrahepatic cholangiocarcinoma (iCCA) is the second most common malignant primary liver cancer. iCCA may develop on an underlying chronic liver disease and its incidence is growing in relation with the epidemics of obesity and metabolic diseases. In contrast, perihilar cholangiocarcinoma (pCCA) may follow a history of chronic inflammatory diseases of the biliary tract. The initial management of CCAs is often complex and requires multidisciplinary expertise. The French Association for the Study of the Liver wished to organize guidelines in order to summarize the best evidence available about several key points in iCCA and pCCA. These guidelines have been elaborated based on the level of evidence available in the literature and each recommendation has been analysed, discussed and voted by the panel of experts. They describe the epidemiology of CCA as well as how patients with iCCA or pCCA should be managed from diagnosis to treatment. The most recent developments of personalized medicine and use of targeted therapies are also highlighted.

A case of fine-needle aspiration of a neck mass with atypical squamous cells and macrophages

Head and neck lesions often undergo fine-needle aspiration to determine the appropriate management and therapeutic decisions. However, there are numerous diagnostic challenges encountered with these specimens, particularly, if atypical squamous cells are identified. Here, we present a case of an enlarging right neck mass in a 38-year-old female and discuss the diagnostic difficulties and potential pitfalls. Additionally, we review the approach to diagnosis, including differential diagnostic considerations as well as available ancillary testing.

Utility of Wnt family member 9b (Wnt9b) immunohistochemistry in the cytologic diagnosis of metastatic breast carcinoma

Wnt family member 9b (Wnt9b) has been demonstrated as a valuable marker for breast cancer diagnosis in surgical pathology. In this study, we examined the utility of Wnt9b in diagnosing metastatic breast carcinoma in cytology samples. Cell blocks from fine needle aspirations (FNA) and fluid specimens of 96 metastatic breast carcinomas and 123 primary and metastatic non-breast neoplasms from various organ systems were evaluated by Wnt9b and GATA3 immunohistochemistry (IHC). Wnt9b and GATA3 were positive in 81.3% and 92.7% of metastatic breast carcinomas, respectively. Conversely, 93.5% and 90.0% of non-breast, non-urothelial carcinomas were negative for Wnt9b and GATA3, respectively. Wnt9b expression was positive in rare gastrointestinal, gynecological, lung, pancreas, and salivary gland tumors. All twenty-eight urothelial carcinomas were negative for Wnt9b, while twenty-six (92.9%) were positive for GATA3. Wnt9b was slightly less sensitive but more specific than GATA3 in diagnosing metastatic breast cancer in cytology samples. Particularly, Wnt9b shows higher specificity in differentiating breast and urothelial primaries. The combined use of Wnt9b and GATA3 may increase diagnostic accuracy.

TRPS1, a sensitive marker for different histological and molecular types of breast cancer

OBJECTIVES

We explored Trichorhinophalangeal syndrome type 1 (TRPS1) expression in special types of breast carcinoma, and analyzed the correlation between TRPS1 and androgen receptor (AR) expression in triple-negative breast cancer (TNBC).

METHODS

TRPS1 expression was analyzed in 801 patients with special types of breast carcinoma. A total of 969 TNBC were used to analyze the correlation between the expression of TRPS1 and AR. TRPS1 expression was evaluated in 1975 cases of breast cancer with different molecular types.

RESULTS

A total of 801 special types of breast cancers were stained with TRPS1.TRPS1 was positive in 100% (63/63) of mucinous carcinoma, 100% (7/7) adenoid cystic carcinomas (4 classic adenoid cystic carcinomas and 3 solid-basaloid adenoid cystic carcinomas), 100% (4/4) tubular carcinomas, 100% (2/2) secretory carcinomas, and 99.59% (243/244) invasive lobular carcinomas, 99.26% (267/269) invasive micropapillary carcinomas, 97.44% (38/39) ER-positive neuroendocrine tumors, 94.44% (34/36) metaplastic breast carcinomas (MBCs), 63.73% (65/102) apocrine carcinomas. TRPS1 was negative in all triple-negative neuroendocrine carcinomas (0/7).TRPS1 was positive in 92.86% (26/28) of metastatic special types of breast cancer. TRPS1 and AR expression were analyzed in 969 cases of TNBC. 90.40% were positive for TRPS1, and 42.41% were positive for AR. A significant inverse correlation between TRPS1 and AR expression was shown in TNBC (p < .001). TRPS1 showed a higher positive rate (93.13%) in TNBC compared to GATA binding protein 3 (GATA3), gross cystic disease fluid protein 15 (GCDFP-15) and forkhead box transcription Factor C 1 (FOXC1).

CONCLUSIONS

In conclusion, our study demonstrated that TRPS1 is a highly sensitive marker for most special types of breast carcinoma. TRPS1 was positive in 63.73% of apocrine carcinomas. TRPS1 and AR expression was inversely correlated in TNBC.

Giant cell carcinoma of the urinary bladder : Clinicopathologic analysis and oncological outcomes

We present the clinicopathological features of 23 cases of the giant cell subtype of urothelial carcinoma, a rare subtype of bladder cancer recognized in the current World Health Organization classification of urological tumors. Histologically, the architectural pattern of the tumor varied from infiltrating to the solid expansile pleomorphic tumor with giant, bizarre, anaplastic cells. Typical or atypical mitotic figures were frequently present in all cases. Between 10 and 30% of the tumor had a giant cell component. All cases were associated with conventional high-grade urothelial carcinoma, with areas of squamous cell divergent differentiation and micropapillary carcinoma present in six and two cases, respectively. In one case each had sarcomatoid, nested, small cell, or glandular divergent differentiation. At diagnosis, 35% of patients had advanced disease and 12% had distant metastases. When comparing giant cell urothelial carcinoma with conventional urothelial carcinoma in a matched analysis, differences in overall and cancer-specific survival were observed, particularly in the T1 stage category. Immunohistochemical staining showed a similar profile of urothelial lineage with frequent positive expression of uroplakin II, GATA3, CK20, CK7, and S100P in both giant cell and conventional urothelial carcinomas. High Ki67 proliferation (range, 60-90%; mean, 71%) and nuclear p53 accumulation (mutant profile; range, 50-90%; mean, 64%) were observed. Using the 22C3 assay, the expression of PD-L1 was found to be variable in two cases, and beta-HCG was negative. In conclusion, giant cell carcinoma is a subtype of urothelial carcinoma associated with advanced clinical stage and a trend to lower survival rates.

Immunohistochemistry Markers in Ovarian and Fallopian Tube Neoplasms: a Comprehensive Review

Immunohistochemistry (IHC) has emerged as a crucial tool in diagnosing and managing ovarian cancer, offering invaluable insights into tumor biology and guiding therapeutic decisions. The intricate histopathological landscape of ovarian cancer presents challenges in accurate diagnosis and classification. IHC offers a complementary approach, aiding in the characterization of tumor subtypes, prognostication, and prediction of treatment response. By targeting specific biomarkers, IHC enables the identification of diverse histological features and molecular alterations associated with ovarian malignancies. The integration of IHC into routine diagnostic workflows enhances diagnostic accuracy, aids in the subclassification of ovarian tumors, and facilitates personalized treatment strategies. Emphasis is placed on the judicious selection of antibody panels tailored to specific clinical scenarios, ensuring optimal utilization of resources and minimizing diagnostic pitfalls. Overall, this review underscores the pivotal role of IHC in refining the diagnosis, prognostication, and management of ovarian cancer, highlighting its significance in the era of precision medicine. By leveraging the molecular insights provided by IHC, clinicians and pathologists can optimize patient care and improve outcomes in ovarian cancer management.

Deciphering Breast Origin in Malignant Effusions: The Diagnostic Utility of an MGP, GATA-3, and TRPS-1 Immunocytochemical Panel

INTRODUCTION

Defining the origin of metastatic cancer is crucial for establishing an optimal treatment strategy, especially when obtaining sufficient tissue from secondary malignancies is limited. While cytological examination is often used in this diagnostic setting, morphologic analysis alone often fails to differentiate metastases derived from the breast from other primaries. The hormone receptor, human epidermal growth factor receptor-2, gross cystic disease fluid protein 15, and mammaglobin immunohistochemistry are often used to diagnose metastatic breast cancer. However, their effectiveness decreases in estrogen receptor (ER)-negative breast cancers, including the triple-negative breast cancer (TNBC) subtype.

METHODS

We conducted a comprehensive evaluation of GATA-binding protein 3 (GATA-3), trichorhinophalangeal syndrome type 1 (TRPS-1), and Matrix Gla Protein (MGP) immunochemistry across 140 effusion cytology specimens with metastatic adenocarcinoma derived from various primaries, including the breast, colon, pancreaticobiliary, lung, tubo-ovarian, and stomach.

RESULTS

The expression rates of these immunomarkers were significantly higher in metastatic cancers originating from the breast than other primaries. In TNBC, TRPS-1 (80.00%) and MGP (65.00%) exhibited higher positivity rates compared to GATA-3 (40.00%). Additionally, our data suggest that an immunohistochemical panel comprising MGP, GATA-3, and TRPS-1 significantly enhances the detection of metastatic breast cancer in effusion cytology specimens, including TNBC in particular. When considering dual-marker positivity, the diagnostic accuracy was found to be 89.29% across all breast cancer subtypes and 92.93% for TNBC.

CONCLUSIONS

MGP appears to be a robust marker for identifying metastatic breast cancer in malignant effusions, especially TNBC. MGP notably enhances diagnostic accuracy when incorporated together with GATA-3 and TRPS-1 in an immunohistochemical panel.

Immunohistochemical Evaluation of Schlafen 11 (SLFN11) Expression in Cancer in the Search of Biomarker-Informed Treatment Targets: A Study of 127 Entities Represented by 6658 Tumors

Schlafen 11 (SLFN11), a DNA/RNA helicase, acts as a regulator of cellular response to replicative stress and irreversibly triggers replication block and cell death. Several preclinical in vitro studies and clinical trials established that SLFN11 expression predicts outcomes in patients with advanced cancer treated with DNA-damaging chemotherapeutics and more recently with poly(ADP-ribose) polymerase inhibitors. SLFN11 expression status remains unknown in many cancer types, especially in mesenchymal tumors. This study evaluated a cohort of well characterized 3808 epithelial and 2850 mesenchymal and neuroectodermal tumors for SLFN11 expression using immunohistochemistry. Nuclear SLFN11 expression was rare in some of the most common carcinomas, for example, hepatocellular (1%), prostatic (2%), colorectal (5%), or breast (16%) cancers. In contrast, other epithelial tumors including mesotheliomas (92%), clear cell renal cell carcinomas (79%), small cell lung cancers (76%), squamous cell carcinomas of the tonsil (89%) and larynx (71%), or ovarian serous carcinomas (69%) were mostly SLFN11-positive. Compared with epithelial malignancies, SLFN11 expression was overall higher in neuroectodermal and mesenchymal tumors. Most positive entities included desmoplastic small round cell tumor (100%), Ewing sarcoma (92%), undifferentiated sarcoma (92%), solitary fibrous tumor (91%), dedifferentiated liposarcoma (89%), synovial sarcoma (86%), and malignant peripheral nerve sheath tumor (85%). Also, this study identifies tumors with potentially worse response to DNA-damaging drugs including antibody drug conjugates due to the absence of SLFN11 expression. Such entities may benefit from alternative treatments or strategies to overcome SLFN11 deficiency-related drug resistance. Our approach and results should serve as a foundation for future biomarker-associated clinical trials.

Primary Epithelioid Angiosarcoma of the Submandibular Gland-A Case Report with Histology-Cytology Correlation and Comprehensive Molecular Analysis

BACKGROUND

Angiosarcoma is a sarcoma that occurs in a range of tissue types, and only rarely in the salivary glands, showing a predilection for the parotid glands of older patients. Preoperative diagnosis may be challenging, especially on cytology, with significant morphological overlap with high-grade primary salivary gland carcinomas. The molecular alterations of this rare salivary gland neoplasm are also not well-characterized.

METHODS AND RESULTS

We present a case of right submandibular gland swelling in a 73-year-old male. On fine needle aspiration, including immunohistochemical stains on cell block, the tumor was initially diagnosed as poorly differentiated carcinoma. Resection of the submandibular gland revealed epithelioid angiosarcoma. We performed molecular work-up of the tumor, utilizing targeted next-generation sequencing, DNA methylation profiling and fluorescence in-situ hybridization. Histopathologic assessment revealed an infiltrative tumor comprising solid sheets of epithelioid cells. The tumor cells formed haphazardly anastomosing vascular channels with intracytoplasmic lumina containing red blood cells. On immunohistochemistry, the tumor cells were positive for CD31, CD34 and ERG. Approximately 40% of the tumor cells showed nuclear expression of GATA3. A pathogenic TP53 R267W mutation was detected on next-generation sequencing. DNA methylation analysis did not cluster the tumor with any known sarcoma type. Copy number analysis showed possible MYC amplification and CDKN2A losses, although only the latter was confirmed on fluorescence in-situ hybridization.

CONCLUSION

Epithelioid angiosarcoma is an important differential diagnosis to high-grade salivary gland carcinoma. In particular, GATA3 expression may be encountered in both angiosarcoma and high-grade salivary gland carcinomas and cause diagnostic confusion. Identification of TP53 mutations and CDKN2A losses suggest shared oncogenic pathways with soft tissue angiosarcomas, and should be further investigated.

Gastric Metastasis Mimicking Early Gastric Cancer from Invasive Ductal Carcinoma of the Breast: Case Report and Literature Review

Backgound and Objectives: Gastric metastasis from invasive ductal breast cancer (BC) is rare. It mainly occurs in patients with lobular BC. The occurrence of multiple metastases is typically observed several years after the primary diagnosis. Endoscopic findings of gastric metastasis of the BC were usually the linitis plastic type. Case presentation: A 72-year-old women who underwent right modified radical mastectomy (MRM) 10 month ago was referred after being diagnosed with early gastric cancer (EGC) during systemic chemotherapy. EGC type I was found at gastric fundus, and pathologic finding showed poorly differentiated adenocarcinoma. Metachronous double primary tumor EGC was considered. Management and Outcome: A laparoscopic total gastrectomy was performed, and postoperative pathology revealed submucosa invasion and two lymph node metastases. A pathologic review that focused on immunohistochemical studies of selected antibodies such as GATA binding protein 3 (GATA3), gross cystic disease fluid protein-15 (GCDFP-15), cytokeratin 7 (CK7) was performed again, comparing previous results. As a result, gastric metastasis from BC was diagnosed. After totally laparoscopic total gastrectomy, palliative first-line chemotherapy with paclitaxel/CDDP was performed. Two months after gastrectomy, she was diagnosed with para-aortic lymph node metastasis and multiple bone metastases. She expired six months after gastrectomy. Conclusions: Gastric metastasis from invasive ductal carcinoma of the breast, which is clinically manifested as EGC, is a very rare condition. If there is a history of BC, careful pathological review will be required.

Fine-needle aspiration diagnosis of secondary malignant tumors of the thyroid gland: A single-institution experience of 17 cases

BACKGROUND

Fine-needle aspiration (FNA) is the most commonly used preoperative pathological diagnostic tool for thyroid tumors. Secondary malignant tumors of the thyroid gland account for less than 3% of all thyroid malignancies. The aim of this study was to investigate the types and cytopathological features of secondary thyroid tumors, evaluate diagnostic pitfalls in FNA.

METHODS

Cases of secondary thyroid tumors diagnosed in the Department of Pathology of Shaanxi Provincial People's Hospital were collected, and their clinical data, cytologic features, immunohistochemical results, and histopathological diagnoses were summarized.

RESULTS

The study included 17 cases (8 males and 9 females) with a mean age of 60.4 ± 9.4 years (range, 45-83 years). Six cases had a known history of primary malignancy prior to FNA aspiration diagnosis. The most common organs of origin were the lungs (5 cases, 3 adenocarcinoma, and 2 small-cell carcinoma) and esophagus (5 cases, 3 squamous-cell carcinoma, 1 adenocarcinoma, and 1 small-cell carcinoma). The next most common was squamous-cell carcinoma of the larynx (3 cases), and gastric tumor (2 cases), including 1 lymphoma and 1 adenocarcinoma. Cell blocks and immunohistochemistry were performed in 12 of these cases. Comparison of the impact of positive history and IHC availability on the accuracy of pathologic diagnosis showed that both were statistically significant.

CONCLUSION

FNA is an effective means of diagnosing secondary malignancies of the thyroid, in which knowledge of the patient's history of malignancy is essential, and the use of cell blocks and immunohistochemistry helps to clarify the pathological diagnosis.

Diagnosis of verruciform acanthotic vulvar intra-epithelial neoplasia (vaVIN) using CK17, SOX2 and GATA3 immunohistochemistry

AIMS

Verruciform acanthotic vulvar intra-epithelial neoplasia (vaVIN) is an HPV-independent, p53 wild-type lesion with distinct morphology and documented risk of recurrence and cancer progression. vaVIN is rare, and prospective distinction from non-neoplastic hyperplastic lesions can be difficult. CK17, SOX2 and GATA3 immunohistochemistry has emerging value in the diagnosis of HPV-independent lesions, particularly differentiated VIN. We aimed to test the combined value of these markers in the diagnosis of vaVIN versus its non-neoplastic differentials in the vulva.

METHODS AND RESULTS

CK17, SOX2 and GATA3 immunohistochemistry was evaluated on 16 vaVINs and 34 mimickers (verruciform xanthoma, lichen simplex chronicus, lichen sclerosus, psoriasis, pseudo-epitheliomatous hyperplasia). CK17 was scored as 3+ = full-thickness, 2+ = partial-thickness, 1+ = patchy, 0 = absent; SOX2 as 3+ = strong staining ≥ 10% cells, 2+ = moderate, 1 + =weak, 0 = staining in < 10% cells; and GATA3 as pattern 0 = loss in < 25% basal cells, 1 = loss in 25-75% basal cells, 2 = loss in > 75% basal cells. For analysis, results were recorded as positive (CK17 = 3+, SOX2 = 3+, GATA3 = patterns 1/2) or negative (CK17 = 2+/1+/0, SOX2 = 2+/1+/0, GATA3 = pattern 0). CK17, SOX2 and GATA3 positivity was documented in 81, 75 and 58% vaVINs, respectively, versus 32, 17 and 22% of non-neoplastic mimickers, respectively; ≥ 2 marker positivity conferred 83 sensitivity, 88 specificity and 86% accuracy in vaVIN diagnosis. Compared to vaVIN, SOX2 and GATA3 were differentially expressed in lichen sclerosus, lichen simplex chronicus and pseudo-epitheliomatous hyperplasia, whereas CK17 was differentially expressed in verruciform xanthoma and adjacent normal mucosa.

CONCLUSIONS

CK17, SOX2 and GATA3 can be useful in the diagnosis of vaVIN and its distinction from hyperplastic non-neoplastic vulvar lesions. Although CK17 has higher sensitivity, SOX2 and GATA3 are more specific, and the combination of all markers shows optimal diagnostic accuracy.

A Subset of Thoracic SMARCA4-Deficient Undifferentiated Tumors Express GATA3

Thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT) is a rare and highly aggressive malignant neoplasm characterized by high-grade undifferentiated morphologic features and recurrent inactivating mutations of SMARCA4. These tumors consistently exhibit loss of SMARCA4 (BRG1) while displaying variable expression of other nonspecific markers. Recently, we encountered a SMARCA4-UT demonstrating immunoreactivity for GATA3, and we sought to characterize this phenomenon in a larger series.

A total of nine SMARCA4-UTs were examined from 3 large academic institutions. The clinicopathologic and molecular characteristics were studied and GATA3 immunohistochemistry was performed.

The cohort included 5 male and 4 female patients, with a median age of 54 years and a median smoking history of 37 pack-years. At initial diagnosis, mediastinal lymph node involvement was observed in 5 patients (56%) while distant metastases were present in 7 patients (78%). The median survival was 6 months. Histologically, the tumors were characterized by sheets of undifferentiated epithelioid and/or rhabdoid cells, accompanied by frequent mitotic figures and necrosis. Immunohistochemically, all tumors displayed a complete loss of BRG1 expression. Notably, 4 of 9 tumors (44%) were positive for GATA3 expression, including one tumor that exhibited strong and diffuse immunoreactivity.

GATA3 expression in SMARCA4-UT may pose diagnostic challenges, requiring differentiation from other GATA3-positive tumors. This distinction is crucial for accurate prognostication and treatment decisions.

Diagnostic utility and sensitivities of matrix Gla protein (MGP), TRPS1 and GATA3 in breast cancer: focusing on metastatic breast cancer, invasive breast carcinoma with special features, and salivary gland-type tumours

Matrix Gla protein (MGP) and trichorhinophalangeal syndrome type 1 (TRPS1) have recently emerged as novel breast-specific immunohistochemical (IHC) markers, particularly for triple-negative breast cancer (TNBC) and metaplastic carcinoma. The present study aimed to validate and compare the expression of MGP, TRPS1 and GATA binding protein 3 (GATA3) in metastatic breast carcinoma (MBC), invasive breast carcinoma (IBC) with special features, including special types of invasive breast carcinoma (IBC-STs) and invasive breast carcinoma of no special type with unique features, and mammary and non-mammary salivary gland-type tumours (SGTs). Among all enrolled cases, MGP, TRPS1 and GATA3 had comparable high positivity for ER/PR-positive (p=0.148) and HER2-positive (p=0.310) breast carcinoma (BC), while GATA3 positivity was significantly lower in TNBC (p<0.001). Similarly, the positive rates of MGP and TRPS1 in MBCs (99.4%), were higher than in GATA3 (90.9%, p<0.001). Among the IBC-STs, 98.4% of invasive lobular carcinomas (ILCs) were positive for all three markers. Among neuroendocrine tumours (NTs), all cases were positive for TRPS1 and GATA3, while MGP positivity was relatively low (81.8%, p=0.313). In the neuroendocrine carcinoma (NC) subgroup, all cases were positive for GATA3 and MGP, while one case was negative for TRPS1. All carcinomas with apocrine differentiation (APOs) were positive for GATA3 and MGP, while only 60% of the cases demonstrated moderate staining for TRPS1. Among mammary SGTs, MGP demonstrated the highest positivity (100%), followed by TRPS1 (96.0%) and GATA3 (72.0%). Positive staining for these markers was also frequently observed in non-mammary SGTs. Our findings further validate the high sensitivity of MGP and TRPS1 in MBCs, IBC-STs, and breast SGTs. However, none of these markers are capable of distinguishing between mammary and non-mammary SGTs.

Nonmesothelial Spindle Cell Tumors of Pleura and Pericardium

Spindle cell lesions of the pleura and pericardium are rare. Distinction from sarcomatoid mesothelioma, which has a range of morphologic patterns, can be difficult, but accurate diagnosis matters. This article provides practical guidance for the diagnosis of pleural spindle cell neoplasms, focusing on primary lesions.

Clinicopathologic features and genomic profiling of female axillary lymph node metastases from adenocarcinoma or poorly differentiated carcinoma of unknown primary

PURPOSE

Axillary lymph node metastases from adenocarcinoma or poorly differentiated carcinoma of unknown primary (CUPAx) is a rare disease in women. This retrospective study intended to examine the clinicopathological features of CUPAx and compared CUPAx genetically with axillary lymph node metastases from breast cancer (BCAx), investigating differences in their biological behavior.

METHODS

We conducted the clinical and prognostic analysis of 58 CUPAx patients in West China Hospital spanning from 2009 to 2021. Gemonic profiling of 12 CUPAx patients and 16 BCAx patients was conducted by the FoundationOne CDx (F1CDx) platform. Moreover, we also compared the gene mutation spectrum and relevant pathways between the two groups and both TCGA and COSMIC databases.

RESULTS

The majority of the 58 CUPAx patients were HR-/HER2- subtype. Most patients received mastectomy combined radiotherapy (50 Gy/25f). CUPAx patients who received mastectomy instead of breast-conserving surgery had a more favorable overall prognosis. Radiotherapy in chest wall/breast and supraclavicular/infraclavicular fossa was the independent prognostic factor (HR = 0.05, 95%CI = 0.00-0.93, P = 0.04). In 28 sequencing samples (CUPAx, n = 12, BCAx, n = 16) and 401 TCGA-BRCA patients, IRS2 only mutated in CUPAx (33.33%) but amplified in BCAx (11.11%) and TCGA-BRCA (1.5%). Pathway analysis revealed that BCAx had more NOTCH pathway mutations than CUPAx. Enrichment analysis showed that CUPAx enriched more in mammary development and PML bodies than BCAx, but less in the positive regulation of kinase activity.

CONCLUSIONS

More active treatment methods, like chemotherapy, mastectomy and postoperative radiotherapy, could improve the prognosis of CUPAx. The differential mutation genes of CUPAx and BCAx might be associated with their respective biological behaviors like invasiveness and prognosis.

Diagnostic Biomarkers in Renal Cell Tumors According to the Latest WHO Classification: A Focus on Selected New Entities

The fifth edition of the World Health Organization (WHO) classification for urogenital tumors, released in 2022, introduces some novelties in the chapter on renal epithelial tumors compared to the previous 2016 classification. Significant changes include the recognition of new disease entities and adjustments in the nomenclature for certain pathologies. Notably, each tumor entity now includes minimum essential and desirable criteria for reliable diagnosis. This classification highlights the importance of biological and molecular characterization alongside traditional cytological and architectural features. In this view, immunophenotyping through immunohistochemistry (IHC) plays a crucial role in bridging morphology and genetics. This article aims to present and discuss the role of key immunohistochemical markers that support the diagnosis of new entities recognized in the WHO classification, focusing on critical topics associated with single markers, in the context of specific tumors, such as the clear cell capillary renal cell tumor (CCPRCT), eosinophilic solid and cystic renal cell carcinoma (ESC-RCC), and so-called "other oncocytic tumors", namely the eosinophilic vacuolated tumor (EVT) and low-grade oncocytic tumor (LOT). Their distinctive characteristics and immunophenotypic profiles, along with insights regarding diagnostic challenges and the differential diagnosis of these tumors, are provided. This state-of-the-art review offers valuable insights in biomarkers associated with novel renal tumors, as well as a tool to implement diagnostic strategies in routine practice.

Trichorhinophalangeal Syndrome Type 1 Immunohistochemical Expression in Carcinomas of Gynecologic Origin

Trichorhinophalangeal syndrome type 1 (TRPS1) is a new reportedly sensitive and specific immunohistochemical marker for carcinomas of breast origin, including triple-negative (estrogen receptor, progesterone receptor, and HER2) tumors. In our practice, we have observed a subset of cases of nonmammary carcinomas that are positive for TRPS1, with higher frequency in cytology effusion samples with metastatic gynecologic malignancies. This study aimed to evaluate the expression of TRPS1 in a large tissue cohort of Müllerian carcinomas. We retrospectively retrieved 105 cases of formalin-fixed paraffin-embedded gynecologic tumors from our surgical pathology archives. Cases corresponded to tumors of tubo-ovarian (17 high-grade serous carcinomas, 3 low-grade serous carcinomas, 2 clear cell carcinomas, and 8 endometrioid adenocarcinomas), endometrial (25 endometrioid adenocarcinomas, 8 serous carcinomas, 6 clear cell carcinomas, 12 carcinosarcomas, 1 dedifferentiated carcinoma, and 1 mesonephric-like adenocarcinoma), cervical (6 human papillomavirus [HPV]-associated squamous cell carcinomas [SCCs], 11 HPV-associated endocervical adenocarcinomas, and 2 HPV-independent gastric-type endocervical adenocarcinomas), and vulvar (2 HPV-independent SCCs and 1 HPV-associated SCC) origins. Immunohistochemistry for TRPS1 was performed in whole tissue sections and assessed for positivity (≥5% of nuclear labeling), distribution (focal: 5% to 49%, diffuse: 50% to 100%), and intensity (1+, 2+, 3+) in tumor cells. Positive TRPS1 staining was observed in 51.4% (54/105) of cases. Most tumors (64.8%) demonstrated diffuse labeling, while focal in 35.2%. Among positive cases, the intensity was predominantly 1+ (57.4%), followed by 2+ (33.3%) and 3+ (9.2%). Tumors with a high percentage of positivity overall consisted of tubo-ovarian (70%) and endometrial carcinomas (58.4%). TRPS1 immunostain is often expressed in gynecologic carcinomas. Awareness of this phenomenon is crucial when evaluating challenging cases in which the differential diagnosis includes a malignancy of breast origin, to avoid misclassification of the primary site.

Analysis of GATA3 and FOXA2 expression suggests that downregulation of genes involved in the maintenance of a mature yolk sac tumor phenotype may underlie sarcomatoid transformation

In the post-chemotherapy setting, germ cell tumors of the testis (GCTT) that resemble non-specific sarcomas and co-express cytokeratins and glypican-3 (GPC3) are diagnosed as "sarcomatoid yolk sac tumor postpubertal-type (YSTpt)". The diagnosis of sarcomatoid YSTpt is clinically relevant but challenging due to its rarity, non-specific histology, and negative α-fetoprotein (AFP) staining. Recently, FOXA2 has emerged as a key-gene in the reprogramming of GCTT (activating the transcription of several genes, among which GATA3), and immunohistochemical studies showed that GATA3 and FOXA2 have a higher sensitivity for non-sarcomatoid YSTpt than GPC3 and AFP. We found that sarcomatoid YSTpt did not express FOXA2 [0: 14/14 (100%)] and showed focal expression of GATA3 [0: 12/14 (85.7%), 1 + : 2/14 (14.3%)], thus suggesting that these markers are not useful in diagnosing this tumor. Furthermore, we proposed a potential mechanism of sarcomatoid transformation in the post-chemotherapy setting of GCTT, mediated by the downregulation of FOXA2 and GATA3.

TRPS1 is a promising marker for all subtypes of breast cancer

AIMS

Trichorhinophalangeal syndrome-1 (TRPS1) has been proposed as a novel breast marker with equally high expression in breast cancer (BC) subtypes, making it a useful diagnostic tool. Here, its expression was evaluated alongside other commonly used markers [GATA3, GCDFP15, mammaglobin (MGB) and SOX10] in a large cohort of BCs (n = 1852) and their corresponding nodal metastases. Its usefulness as a diagnostic tool and its correlation with clinicopathological features were assessed.

METHODS AND RESULTS

TRPS1 was expressed at 75.8% overall in the BC cohort, with at least 58% expression among BC subtypes. It was less sensitive than GATA3 for luminal and HER2-overexpressing (HER2-OE) cancers (luminal A: 82 versus 97%; luminal B: 80 versus 95%; HER2-OE: 62 versus 76%), but it was the most sensitive for TNBC (60 versus ≤ 41%). It showed a stable expression in nodal metastases (primary tumour 76 versus nodal metastasis 78%), unlike a reduced nodal expression for GATA3 (86 versus 77%). TRPS1 outperformed GATA3 in detecting non-luminal cancers when paired with other breast markers. TRPS1 and GCDFP15 was the most sensitive combination in TNBC detection, with a 76% detection rate. For TRPS1-negative and GCDFP15-negative TNBCs, SOX10 was more sensitive than GATA3 (29 versus 24%).

CONCLUSIONS

TRPS1 is a highly sensitive marker for all breast cancer subtypes, outperforming GATA3 in non-luminal cancers and displaying the highest sensitivity for TNBC detection when combined with GCDFP15. It is a valuable addition to the breast marker panel for accurate identification of BC.

Immunohistochemical Characterization of a Large Cohort of Triple Negative Breast Cancer

Introduction. Triple negative breast carcinomas are characterized by a lack of hormone receptor and HER2 expression and inconsistent expression of breast-specific immunohistochemical markers. The expression of many site-specific markers in these tumors is largely unknown. The objective of the study was to examine the expression of widely used immunohistochemical markers on a large cohort of triple negative breast cancer. Methods. Sections from tissue microarrays were stained with 47 markers using routine protocols. Most markers were scored using a modified Allred method. ATRX, BAP1, SMAD4, e-cadherin, and beta-catenin were scored as retained or lost. Mammaglobin was considered positive if there was at least moderate intensity staining in any tumor cells. P16 was scored as overexpressed or not overexpressed; p53 was scored as wildtype, overexpressed, null, or cytoplasmic. Results. The cohort consisted of 639 tumors including 601 primary and 32 metastases. Overall, 96% expressed GATA3, mammaglobin, and/or SOX10 while 97% of no special type tumors expressed this panel. Carcinoma of apocrine differentiation demonstrated an AR positive, SOX10 negative, K5 negative/focal immunophenotype. PAX8 (SP348), WT1, Napsin A, and TTF1 (8G7G3/1) were never or rarely expressed while CA9, CDX2, NKX3.1, SATB2 (SATBA410), synaptophysin, and vimentin were variably expressed. Conclusions. Almost all TNBC express at least 1 of the 3 IHC markers: GATA3, mammaglobin, and/or SOX10. Carcinoma of apocrine differentiation is characterized by an AR positive, SOX10 negative, K5 negative or focal immunophenotype. Cautious interpretation of so-called site-specific markers, with knowledge of antibody clones, is required in excluding the diagnosis of triple negative breast cancer.

An Updated Contextual Approach to Mesothelial Proliferations in Pleural Effusion Cytology Leveraging Morphology, Ancillary Studies, and Novel Biomarkers

CONTEXT.—

Pleural effusions are common cytologic specimens that can be leveraged to make diagnoses of malignancy that drive appropriate patient management. However, the overlap in morphologic features of reactive mesothelial proliferations, mesotheliomas, and adenocarcinomas can create diagnostic pitfalls in the cytologic evaluation of pleural fluids.

OBJECTIVE.—

To review the morphologic spectrum of benign and malignant mesothelial proliferations in pleural effusions, as well as relevant clinicoradiologic contexts and ancillary tests.

DATA SOURCES.—

Existing scientific and clinical literature as of January 2023.

CONCLUSIONS.—

We can leverage the knowledge of several overlapping morphologic features, clinicoradiologic scenarios, and immunohistochemical studies to enhance the diagnostic accuracy of pleural effusion cytology to appropriately delineate cases of adenocarcinoma, reactive mesothelial proliferation, and mesothelioma. Earlier diagnosis through cytology, particularly in cases of mesothelioma, may positively impact patient treatment options and prognosis.

Diagnostic Utility of GATA3 and ISL1 in Differentiating Neuroblastoma From Other Pediatric Malignant Small Round Blue Cell Tumors

Accurate diagnosis of neuroblastoma may be challenging, especially with limited or inadequate specimen and at the metastatic sites due to overlapping imaging, histopathologic, and immunohistochemical (immunohistochemistry [IHC]; infidelity among various lineage-associated transcription factors eg FLI1, transducin-like enhancer 1, etc) features. GATA3 and ISL1 have recently been described as markers of neuroblastic differentiation. This study aims at determining the diagnostic utility of GATA3 and ISL1 in differentiating neuroblastoma from other pediatric malignant small round blue cell tumors.

We evaluated GATA3 and ISL1 expression in 74 pediatric small round blue cell tumors that included 23 NMYC-amplified neuroblastomas, 11 EWSR1-rearranged round cell sarcomas, 7 SYT::SSX1-rearranged synovial sarcomas, 5 embryonal rhabdomyosarcomas, 10 Wilms tumors (nephroblastomas), 7 lymphoblastic lymphoma, 7 medulloblastoma, and 4 desmoplastic small round cell tumor.

All 23 neuroblastomas (moderate to strong staining in >50% of the tumor cells), 5 T-lymphoblastic lymphomas (moderate to strong staining in 40%-90% of the tumor cells), and 2 desmoplastic small round cell tumors (weak to moderate staining in 20%-30% of the tumor cells) expressed GATA3, while other tumors were negative. ISL1 immunoreactivity was observed in 22 (96%) neuroblastomas (strong staining in in >50% of the tumor cells, n  =  17; moderate to strong staining in 26%-50% of the tumor cells, n  =  5), 3 embryonal rhabdomyosarcoma (moderate to strong staining in 30%-85% of the tumor cells), 1 synovial sarcoma (weak staining in 20% of the tumor cells), and 7 medulloblastoma (strong staining in 60%-90% of the tumor cells). Other tumors were negative. Overall, GATA3 showed 86% specificity, 100% sensitivity, and 90% accuracy for neuroblastoma, with a positive predictive value (PPV) and negative predictive value (NPV) of 77% and 100%, respectively. ISLI showed 72% specificity, 96% sensitivity, and 81% accuracy for neuroblastoma, with a PPV and NPV of 67% and 97%, respectively. After the exclusion of T-lymphoblastic lymphoma and desmoplastic small round cell tumors, GATA3 had 100% specificity, sensitivity, accuracy, and PPV and NPV for neuroblastoma. Similarly, in pediatric small round blue cell tumors, ISL1 had 100% specificity, sensitivity, accuracy, PPV, and NPV for neuroblastoma, after embryonal rhabdomyosarcoma, synovial sarcoma, and medulloblastoma were excluded.

CONCLUSIONS

GATA3 and ISL1 may be valuable in the diagnostic work-up of neuroblastoma and may reliably be used to support the neuroblastic lineage of pediatric small round blue cell tumors. Furthermore, dual positivity helps in challenging scenarios, when there is equivocal imaging, overlapping IHC features, limited specimen, and the lack of facility for a molecular work up.

Hand2 Immunohistochemistry in the Diagnosis of Paragangliomas and Other Neuroendocrine Neoplasms

Hand2 is a core transcription factor responsible for chromaffin cell differentiation. However, its potential utility in surgical pathology has not been studied. Thus, we aimed to investigate its expression in paragangliomas, other neuroendocrine neoplasms (NENs), and additional non-neuroendocrine tumors. We calibrated Hand2 immunohistochemistry on adrenal medulla cells and analyzed H-scores in 46 paragangliomas (PGs), 9 metastatic PGs, 21 cauda equina neuroendocrine tumors (CENETs), 48 neuroendocrine carcinomas (NECs), 8 olfactory neuroblastomas (ONBs), 110 well-differentiated NETs (WDNETs), 10 adrenal cortical carcinomas, 29 adrenal cortical adenomas, 8 melanomas, 41 different carcinomas, and 10 gastrointestinal stromal tumors (GISTs). Both tissue microarrays (TMAs) and whole sections (WSs) were studied. In 171 NENs, previously published data on Phox2B and GATA3 were correlated with Hand2. Hand2 was positive in 98.1% (54/55) PGs, but only rarely in WDNETs (9.6%, 10/104), CENETs (9.5%, 2/21), NECs (4.2%, 2/48), or ONBs (12.5%, 1/8). Any Hand2 positivity was 98.1% sensitive and 91.7% specific for the diagnosis of PG. The Hand2 H-score was significantly higher in primary PGs compared to Hand2-positive WDNETs (median 166.3 vs. 7.5; p < 0.0001). Metastatic PGs were positive in 88.9% (8/9). No Hand2 positivity was observed in any adrenal cortical neoplasm or other non-neuroendocrine tumors, with exception of 8/10 GISTs. Parasympathetic PGs showed a higher Hand2 H-score compared to sympathetic PGs (median H-scores 280 vs. 104, p < 0.0001). Hand2 positivity in NENs serves as a reliable marker of primary and metastatic PG, since other NENs only rarely exhibit limited Hand2 positivity.

Mesothelioma in the pleura, pericardium and peritoneum: Recommendations from the International Collaboration on Cancer Reporting (ICCR)

AIMS

Mesothelioma is a rare malignancy of the serosal membranes that is commonly related to exposure to asbestos. Despite extensive research and clinical trials, prognosis to date remains poor. Consistent, comprehensive and reproducible pathology reporting form the basis of all future interventions for an individual patient, but also ensures that meaningful data are collected to identify predictive and prognostic markers.

METHODS AND RESULTS

This article details the International Collaboration on Cancer Reporting (ICCR) process and the development of the international consensus mesothelioma reporting data set. It describes the 'core' and 'non-core' elements to be included in pathology reports for mesothelioma of all sites, inclusive of clinical, macroscopic, microscopic and ancillary testing considerations. An international expert panel consisting of pathologists and a medical oncologist produced a set of data items for biopsy and resection specimens based on a critical review and discussion of current evidence, and in light of the changes in the 2021 WHO Classification of Tumours. The commentary focuses particularly upon new entities such as mesothelioma in situ and provides background on relevant and essential ancillary testing as well as implementation of the new requirement for tumour grading.

CONCLUSION

We recommend widespread and consistent implementation of this data set, which will facilitate accurate reporting and enhance the consistency of data collection, improve the comparison of epidemiological data, support retrospective research and ultimately help to improve clinical outcomes. To this end, all data sets are freely available worldwide on the ICCR website (www.iccr-cancer.org/data-sets).

Utility of Immunohistochemistry in the Diagnosis of Pleuropulmonary and Mediastinal Cancers: A Review and Update

CONTEXT.—

Immunohistochemistry has become a valuable ancillary tool for the accurate classification of pleuropulmonary and mediastinal neoplasms necessary for therapeutic decisions and predicting prognostic outcome. Diagnostic accuracy has significantly improved because of the continuous discoveries of tumor-associated biomarkers and the development of effective immunohistochemical panels.

OBJECTIVE.—

To increase the accuracy of diagnosis and classify pleuropulmonary neoplasms through immunohistochemistry.

DATA SOURCES.—

Literature review and the author's research data and personal practice experience.

CONCLUSIONS.—

This review article highlights that appropriately selecting immunohistochemical panels enables pathologists to effectively diagnose most primary pleuropulmonary neoplasms and differentiate primary lung tumors from a variety of metastatic tumors to the lung. Knowing the utilities and pitfalls of each tumor-associated biomarker is essential to avoid potential diagnostic errors.

Thyroid Metastases from Triple-Negative Breast Cancer with High PD-L1 Expression - A Rare Presentation

Thyroid metastases secondary to triple-negative breast cancer are sporadic. Diagnosis usually requires fine needle aspiration biopsy (FNAB) and immunohistochemistry. There are no treatment guidelines for this type of cancer, and to date, reports of chemotherapy combined with immunotherapy in thyroid metastases are very rare. Here, we first report the effectiveness of anti-PD-1 inhibitor in combination with chemotherapy for the treatment of metastatic thyroid cancer secondary to advanced triple-negative breast cancer with high expression of programmed cell death ligand 1 (PD-L1). Following six cycles of albumin paclitaxel (400mg d1/21 days) plus PD-1 antibody inhibitor (Sindilizumab 200mg d1/21 days), the patient experienced significant relief of neck swelling and obstructive feeding, both the thyroid metastases and the right breast lesion regressed completely following six cycles of treatment. Chemotherapy combined with immunotherapy may provide a new direction for unresectable advanced thyroid metastases.

Divergent Lineage Markers in Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) often results from dedifferentiation of differentiated thyroid carcinoma (DTC), and the diagnosis is not difficult, as the tumor is seen to progress from a recognized DTC. However, in some cases, the diagnosis based on biopsy of limited tissue or resection of a completely undifferentiated tumor relies on immunohistochemical biomarkers and is usually a diagnosis of exclusion. To examine the biomarker profile of ATC and to determine whether divergent lineage markers can complicate this process, we examined the expression of a number of biomarkers in a series of ATCs. Cases retrieved from the department laboratory information system were included if there was evidence of an accurate diagnosis based on the presence of a coexisting or antecedent DTC or in cases where the immunoprofile was consistent with thyroid origin in a non-equivocal clinical setting. Questionable cases were excluded. We identified 36 cases for analysis. Tissue sections were stained for PAX8, TTF1, BRAFV600E, NRASQ61R, TRK, and p53, as well as p40, CDX2, SATB2, GATA3, CD117, CD163, SALL4, SMARCA4, PRAME, SOX10, ERG and HEPPAR1. As expected, all 36 ATCs were negative for TTF1 except for one showing focal, weak expression. Thirteen expressed PAX8 with variable intensity. BRAFV600E was positive in 10/34 tumors and equivocal in 3; NRASQ61R was positive in 12, and TRK was positive in 1 case. Staining for p53 was diffusely positive in 14 and completely negative in 19, with only 3 cases showing a wild-type pattern. We found aberrant expression of GATA3 in 11/36 cases, SATB2 in 8/36, CD117 in 2/35, and SALL4 in 1/30. CD163 expression was identified in tumor cells in 10/30 cases with variable intensity; in the other tumors, interpretation was obscured by abundant histiocytes. P40 was positive in 5 cases with squamoid morphology. CDX2 was negative in 35 tested cases. PRAME was identified in 1 of 33 cases. Stains for SOX10, ERG, and HEPPAR1 were negative in 33 cases. Twenty tested cases showed retained SMARCA4 expression. We conclude that ATCs express a number of divergent lineage markers that can cause diagnostic dilemmas, as they are also features of other tumors in the differential diagnosis of high-grade midline neck malignancies.