Thyroid transcription factor-1, thyroglobulin, cytokeratin 7, and cytokeratin 20 in thyroid neoplasms

A pancreatic adenocarcinoma mimicking hepatoid carcinoma of uncertain histogenesis: A case report and literature review

In rare cases, metastatic adenocarcinomas of different origin may exhibit the features of hepatoid carcinoma (HC), a rare malignant epithelial tumor, most commonly occurring in the ovaries and stomach, as well as in the pancreas and biliary ducts. A case of a 72-year-old female patient who developed a highly aggressive, poorly differentiated pancreatic ductal adenocarcinoma with peritoneal carcinomatosis, demonstrating hepatoid differentiation upon conventional hematoxylin and eosin staining is reported in the present study. The patient presented with severe abdominal pain, and the radiological investigations performed revealed ovarian and hepatic tumor masses and peritoneal lesions, which were surgically removed. The gross examination of the peritoneum and omentum revealed multiple solid, firm, grey-white nodules, diffusely infiltrating the adipose tissue. The microscopic examination revealed a malignant epithelial proliferation, composed of polygonal cells with abundant eosinophilic cytoplasm and irregular, pleomorphic nuclei. Certain cells presented with intracytoplasmic mucus inclusions, raising suspicion of a HC with an uncertain histogenesis. Immunohistochemical staining was performed, and the tumor cells were found to be positive for cytokeratin (CK)7, CK18 and mucin 5AC, whereas negative staining for CK20, caudal-type homeobox transcription factor 2, α-fetoprotein, paired box gene 8, GATA-binding protein 3 and Wilms tumor 1 were documented. Thus, the diagnosis of metastatic pancreatic adenocarcinoma was established. The main aim of the present study was to provide further knowledge concerning poorly differentiated metastatic adenocarcinoma resembling HC, emphasizing the histopathological and immunohistochemical features of these malignant lesions and raising awareness of the diagnostic difficulties that may arise, as well as the importance of the use immunohistochemistry in differentiating carcinomas of uncertain histogenesis.

Recurrent Metastatic Colorectal Adenocarcinoma to the Thyroid Gland Presenting With Vocal Cord Paralysis and Inspiratory Stridor

The most common sites for metastases of colorectal cancer include the liver, lungs, brain, and regional lymph nodes. However, a limited number of reported cases describe colon cancer metastasis to the thyroid gland. Metastatic colorectal adenocarcinoma to the thyroid gland is rare. The majority of these cases with colon cancer metastases to the thyroid gland are diagnosed years after initial treatment of colon cancer. The discovery is usually made after routine surveillance imaging, and often patients have minimal or absent symptoms. We report a case of a recurrence of metastatic colorectal adenocarcinoma to the thyroid gland presenting with vocal cord paralysis and inspiratory stridor.

Immunohistochemistry in the pathologic diagnosis and management of thyroid neoplasms

The use of immunohistochemistry cannot be underestimated in the everyday practice of thyroid pathology. It has evolved over the years beyond the traditional confirmation of thyroid origin to molecular profiling and the prediction of clinical behavior. In addition, immunohistochemistry has served to implement changes in the current thyroid tumor classification scheme. It is prudent to perform a panel of immunostains, and the immunoprofile should be interpreted in light of the cytologic and architectural features. Immunohistochemistry can also be easily performed in the limited cellularity specimen preparation generated from thyroid fine-needle aspiration and core biopsy; however, it will require laboratory validation of immunostains specific to these preparations to avoid diagnostic pitfalls. This review discusses the application of immunohistochemistry in thyroid pathology with a focus on limited cellularity preparations.

[CUP syndrome-diagnostics from the perspective of pathology]

PROBLEM

Histologic and immunohistologic workup of tumor material from metastases of a previously unknown primary tumor is important for identifying their origin, but is often insufficient for this purpose without clinical oncologic and radiologic evaluation.

PROCEDURE

In the initial cancer of unknown primary (CUP) situation, histologic and immunohistochemical workup together with clinicoradiologic correlations contribute significantly to the identification of the primary tumor. There are now accepted guidelines to follow when there is an initial CUP situation. Molecular diagnostic tools can be used to investigate changes at the nucleic acid level, which can provide clues about the primary tumor, including potential targets for therapy. If, despite broad and interdisciplinary diagnostics, it is not possible to identify the primary tumor, the diagnosis is CUP syndrome. If a true CUP situation is present, it is important to assign the tumor to a tumor class or a specific therapy-sensitive subgroup as best as possible so that the best possible treatment can be given. However, for a final assignment to a primary tumor or a final classification as CUP, a comparison with medical oncological and imaging findings is indispensable.

CONCLUSION

When CUP is suspected, close interdisciplinary collaboration between pathology, medical oncology, and imaging is essential to achieve a viable classification as CUP or identification of a presumptive primary tumor, in the interest of providing the most specific and effective therapy for affected individuals.

Immunohistochemical investigation of epithelial, mesenchymal, neuroectodermal, immune and endocrine markers in sterlet (Acipenser ruthenus), shortnose sturgeon (Acipenser brevirostrum) and common carp (Cyprinus carpio)

Immunohistochemistry (IHC) is a laboratory method widely used to characterize tissue and cell origin, both in human and veterinary medicine. In fish, however, little is known about staining characteristics of most tissue types, and especially for less studied chondrostean fish. The aim of this study was to examine the specificity of various immunohistochemical markers in tissues of chondrostean and teleostean fish and to validate diagnostic tests. Sterlet (Acipenser ruthenus L.), shortnose sturgeon (Acipenser brevirostrum) and common carp (Cyprinus carpio L.) were examined. Markers were chosen as representatives of epithelial (cytokeratin AE1/AE3), mesenchymal (vimentin), neuroectodermal (S-100 protein), lymphoid (leukocyte common antigen, LCA) and endocrine (thyroglobulin, thyroxin) tissues and organs. Applied antibodies were of monoclonal or polyclonal mammalian origin and primarily intended for human medicine research or diagnostic application. No species differences were obvious while examining sterlet, shortnose sturgeon and carp. Cytokeratin AE1/AE3, vimentin, S-100 protein and thyroxin were positive on targeted tissues and structures. Leukocyte common antigen (LCA) and thyroglobulin were negative on targeted structures, however, and with clear cross-reactivity on non-targeted tissues (vascular wall, granulocytes). Conclusive results were obtained when using polyclonal antibodies with dilution adjusted to laboratory practice, while application of ready-to-use (RTU) kits with pre-diluted antibodies or monoclonal antibodies often showed conflicting or inconclusive results.

Carcinoma of Unknown Primary Origin: Application of Immunohistochemistry With Emphasis to Different Cytokeratin 7 and 20 Staining Patterns

BACKGROUND

Although the primary origin of some carcinomas may be obscure to clinicians, its identification is crucial as it affects prognosis and treatment (especially novel targeted therapies). Immunohistochemistry (IHC) may be helpful in identifying the primary origin of carcinomas. This retrospective survey aimed to evaluate the frequency and accuracy of each IHC marker used to determine the origin of carcinomas.

METHODS

The review of pathology department archives revealed 307 cases of cancer of unknown primary origin (CUP) between 2015 and 2020, which were accessible in the department archives. Demographic information, site of biopsy, clinical and pathologic diagnoses, and IHC results of the patients were collected.

RESULTS

The patients included 157 (51.15%) men and 150 (48.85%) women. The age of the patients ranged from 14 to 92 years, including 106 (34.5%) expired cases. In 27% of cases, the primary origin of carcinoma remained unknown. The agreement between pathologic and clinical diagnoses was 59%. The most common pattern of cytokeratin (CK) expression in CUP was CK7+/CK20- (55.3%), followed by CK7-/CK20- (19%), CK7+/CK20+ (15%), and CK7-/CK20+ (10.7%), respectively.

CONCLUSION

The IHC analysis may improve the diagnosis of CUPs. However, the origin of some cases remains unknown despite an IHC analysis, thereby necessitating the use of more diagnostic procedures or gene expression studies for reaching a definitive diagnosis.

Postoperative radioiodine therapy impact on survival in poorly differentiated thyroid carcinoma: a population-based study

PURPOSE

The true impact of postoperative radioiodine therapy on survival has been controversial for patients with poorly differentiated thyroid carcinoma (PDTC). We aimed to determine the impact of postoperative radioiodine on survival in PDTC through a population-based study.

METHODS

Data on patients with PDTC were collected from the US SEER database (2004 to 2015). Patients were divided into the radioiodine group and nonradioiodine group. Survival comparison between groups was evaluated by Kaplan-Meier curves, log-rank test and multivariate Cox regression analysis. Akaike information criterion was used to select variables in the nomogram. The performance of the nomogram was assessed by discrimination (C-index) and calibration plots.

RESULTS

The radioiodine group had more aggressive features, such as advanced tumor node metastasis stage and radical surgery, compared to the nonradioiodine group. PDTC patients receiving radioiodine therapy had a significant survival advantage in terms of overall survival (OS) (P = 0.001) but not in terms of cancer-specific survival (P = 0.083). Multivariate analysis revealed radioiodine therapy was an independent favorable factor for OS in PDTC patients (hazard ratio = 0.57; 95% CI, 0.44-0.75, P < 0.001). Subgroup analysis identified patients' characteristics favoring radioiodine therapy. The nomogram (age, tumor size, extension, neck lymph nodes metastasis and radioiodine therapy) of OS for predicting 3-, 5- and 10-year OS probability showed good discrimination (C-index, 0.797) and calibration power.

CONCLUSION

Postoperative radioiodine therapy can prolong the long-term OS in patients with PDTC, and is an independent favorable prognostic factor for those patients. Further prospective studies are warranted.

Immunohistochemically detectable thyroglobulin expression in extrathyroidal cancer is 100% specific for thyroidal tumor origin

Thyroglobulin is a secreted 660 kDa glycoprotein produced by thyroid follicular cells used in diagnostic pathology to secure or exclude a thyroidal origin of metastases of unknown primary tumors. This study was performed to estimate specificity of thyroglobulin immunohistochemistry. 9974 tumor samples from 109 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types were analyzed by immunohistochemistry in a tissue microarray format. Thyroglobulin was strongly expressed in all normal thyroid samples but not in any other normal tissues. Thyroglobulin immunostaining was detected in 99.1% of 106 thyroid adenomas, 98.1% of 364 papillary, 95.2% of 147 follicular, and 7.5% of 40 anaplastic thyroid cancers. Twelve of 15 thyroid samples that were thyroglobulin negative on TMAs showed at least a weak focal thyroglobulin positivity in corresponding large sections, suggesting higher sensitivity of large section analysis. Thyroglobulin positivity in one diffuse large B-cell lymphoma of the thyroid, one chondrosarcoma metastasis to the thyroid, and 42.4% of 92 medullary thyroid cancers was considered to be caused by diffusion of thyroidal colloid from destroyed or even intact adjacent follicles. Thyroglobulin positivity was, however, not seen in 6403 extrathyroidal tumors from 104 different tumor types and subtypes. Our data demonstrate a complete specificity of positive thyroglobulin immunostaining for thyroid origin in tumor tissues obtained from extrathyroidal locations. However, for all tumors located within the thyroid, false positivity can occur as a result of tissue contamination by thyroglobulin rich thyroid colloid from adjacent normal tissue.

Metastasis of Papillary Thyroid Carcinoma to the Maxillary Sinus: Case Report and Review of the Literature

Metastasis of the thyroid carcinoma to the paranasal sinuses is rarely reported. Among these sinuses, metastasis to the maxillary sinus alone has been reported only in a few cases. This is the first reported case in a 76-year-old woman with papillary thyroid carcinoma metastasizing to the maxillary sinus alone and resected through endoscopic sinonasal surgery. When patients have sinus lesions and a history of malignancy, metastasis should be included in the differential diagnosis. If they have an isolated metastatic lesion to the paranasal sinus, ESS, either palliative or radical, can be a useful treatment option.

Mandibular Metastasis of Silent Papillary Thyroid Carcinoma: A Rare Case Report with Review of the Literature

Metastasis to the jaws is a rare event; however, it has great importance because it may be the only symptom of an undiagnosed underlying malignancy. Papillary thyroid carcinoma, the commonest histopathologic variant of thyroid cancer, has minimal potential for distant metastasis, and most reported metastatic thyroid carcinomas of the oral cavity have been follicular thyroid carcinoma. The aim of this article is to present a rare case of metastatic papillary thyroid carcinoma, which presented itself as a painless expansion in the anterior region of the mandible in a 56-year-old female, and to review previously published cases of this type of cancer. Reporting rare cases such as this one, together with reviewing previous reports of related rare diseases, will expand the body of knowledge about these uncommon lesions.

Solid variant of papillary thyroid carcinoma: an under-recognized entity

Solid variant of papillary thyroid carcinoma (SVPTC) is a rare morphological variant of papillary thyroid carcinoma (PTC). SVPTC is histologically characterized by predominant solid, trabecular and insular nests of tumor cells while cytological features of PTC such as nuclear grooves and nuclear inclusions are preserved. In fine needle aspiration cytology smears, tumor cells of SVPTC may be presented in cohesive, syncytial or trabecular clusters accompanied by some discohesiveness in the absence of necrosis. Although SVPTC and poorly differentiated thyroid carcinoma (PDTC) share similar histological findings of solid nests, SVPTC can be differentiated from PDTC in the lack of tumor necrosis, severe nuclear atypia, and a higher mitotic index. Immunohistochemical expression of CK19 and HBME-1, common markers of PTC, is decreased in solid nests of SVPTC. In pediatric patients exposed to radiation after the Chernobyl nuclear accident, there was a higher prevalence of SVPTC with RET/PTC3 type rearrangement. BRAF mutations are also reported in a small number of adult patients with SVPTC without any prior radiation exposure. Patients with SVPTC may have a slightly higher incidence of metastasis and recurrence of the tumor compared to conventional PTC, although overall survival rate is comparable. In this article, the current knowledge of SVPTC will be reviewed and discussed with an emphasis on the histopathological feature.

Insulinoma-associated protein 1 (INSM-1) expression in medullary thyroid carcinoma FNA: a multi-institutional study

INTRODUCTION

Insulinoma-associated protein 1 (INSM-1) is expressed in both normal tissues and neoplasms with neuroendocrine differentiation such as small cell lung carcinoma and pancreatic neuroendocrine tumors. The aim of this study was to evaluate the INSM-1 expression in medullary thyroid carcinoma (MTC) in the aspirated material and its preoperative diagnostic value.

MATERIALS AND METHODS

MTC cases with available cytological material from 5 institutions were retrospectively identified. INSM-1 expression was analyzed in 48 cell blocks prepared from fine-needle aspiration samples from histologically confirmed cases of MTC. Twenty-nine samples were aspirates from primary thyroid lesions and 19 from secondary lesions lymph node or liver lesions. INSM-1 immunostain was done using the Ventana Automatic System (Ventana Medical Systems, Tucson, AZ). The control group consisted of 20 samples from histologically confirmed cases of papillary, follicular, and anaplastic thyroid carcinomas and secondary thyroid malignancies (squamous cell carcinoma, malignant melanoma).

RESULTS

The male to female (M:F) ratio in MTC group was 1:1.5 and the average age was 55.6 years (range: 24-84 years). INSM-1 nuclear staining in at least 5% of cells was considered positive. Forty-five (93.75%) MTC samples were positive including all primary tumor aspirates. All control samples were negative.

CONCLUSIONS

INSM-1 nuclear positivity is a reliable marker of MTC neuroendocrine differentiation on cytology material from both primary tumor and metastases. INSM-1 can also discriminate MTC from other primary and secondary thyroid carcinomas when there are cytomorphologic overlaps.

Salutary Response to Targeted Therapy in Anaplastic Thyroid Cancer

Context. Anaplastic thyroid cancer (ATC) is an aggressive tumor with a median survival of 3 to 9 months, a 1-year survival of less than 10% and without definitive therapies. Recently, in BRAF V600E mutated ATCs, new targeted therapy using a combination of a BRAF inhibitor, dabrafenib (Dab), with a mitogen-activated extracellular protein kinase (MEK) inhibitor, trametinib (Tram), has shown significant promise. Case Description. We report a case of aggressive ATC with 5 sequence mutations: BRAF V600E (mutation fraction [MF] 34%), TERT E441del (MF 37%), RET N579K (MF 55%), EZH2 D154E (MF 60%), and CDK4 S259L (MF 48%). The patient had a dramatic response to the Dab/Tram combination with near complete resolution of his lung, bone, hepatic, and splenic lesions soon after starting therapy. Unfortunately, intolerable side effects (grade 2-3) on this regimen required tapering and discontinuation of the treatment. He had a quick resurgence of disease after stopping the combination therapy. The patient died approximately 3 months after discontinuing Dab/Tram. Autopsy revealed an atrophic thyroid gland with microscopic subcapsular focus of well-differentiated papillary thyroid carcinoma. There was extensive lymphatic spread of the tumor throughout bilateral lungs with fibrosis. No other metastatic site was identified. Conclusion. We report a unique case of ATC with 2 new mutations of EZH2 D154E and CDK S529L. This case exemplifies the significant promise Dab/Tram therapy holds, the potential side effects that limit their use, and autopsy findings status post use of this combination therapy.

Mouse Model of Thyroid Cancer Progression and Dedifferentiation Driven by STRN-ALK Expression and Loss of p53: Evidence for the Existence of Two Types of Poorly Differentiated Carcinoma

Background: Thyroid tumor progression from well-differentiated cancer to poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC) involves step-wise dedifferentiation associated with loss of iodine avidity and poor outcomes. ALK fusions, typically STRN-ALK, are found with higher incidence in human PDTC compared with well-differentiated cancer and, as previously shown, can drive the development of murine PDTC. The aim of this study was to evaluate thyroid cancer initiation and progression in mice with concomitant expression of STRN-ALK and inactivation of the tumor suppressor p53 (Trp53) in thyroid follicular cells. Methods: Transgenic mice with thyroid-specific expression of STRN-ALK and biallelic p53 loss were generated and aged on a regular diet or with methimazole and sodium perchlorate goitrogen treatment. Development and progression of thyroid tumors were monitored by using ultrasound imaging, followed by detailed histological and immunohistochemical evaluation. Gene expression analysis was performed on selected tumor samples by using RNA-Seq and quantitative RT-PCR. Results: In mice treated with goitrogen, the first thyroid cancers appeared at 6 months of age, reaching 86% penetrance by the age of 12 months, while a similar rate (71%) of tumor occurrence in mice on regular diet was observed by 18 months of age. Histological examination revealed well-differentiated papillary thyroid carcinomas (PTC) (n = 26), PDTC (n = 21), and ATC (n = 8) that frequently coexisted in the same thyroid gland. The tumors were frequently lethal and associated with the development of lung metastasis in 24% of cases. Histological and immunohistochemical characteristics of these cancers recapitulated tumors seen in humans. Detailed analysis of PDTC revealed two tumor types with distinct cell morphology and immunohistochemical characteristics, designated as PDTC type 1 (PDTC1) and type 2 (PDTC2). Gene expression analysis showed that PDTC1 tumors retained higher expression of thyroid differentiation genes including Tg and Slc5a5 (Nis) as compared with PDTC2 tumors. Conclusions: In this study, we generated a new mouse model of multistep thyroid cancer dedifferentiation with evidence of progression from PTC to PDTC and ATC. Further, PDTC in these mice showed two distinct histologic appearances correlated with levels of expression of thyroid differentiation and iodine metabolism genes, suggesting a possibility of existence of two PDTC types with different functional characteristics and potential implication for therapeutic approaches to these tumors.

Practical Application of Lineage-Specific Immunohistochemistry Markers: Transcription Factors (Sometimes) Behaving Badly

CONTEXT.—

Transcription factors (TFs) are proteins that regulate gene expression and control RNA transcription from DNA. Lineage-specific TFs have increasingly been used by pathologists to determine tumor lineage, especially in the setting of metastatic tumors of unknown primary, among other uses. With experience gathered from its daily application and increasing pitfalls reported from immunohistochemical studies, these often-touted highly specific TFs are not as reliable as once thought.

OBJECTIVES.—

To summarize the established roles of many of the commonly used TFs in clinical practice and to discuss known and potential sources for error (eg, false-positivity from cross-reactivity, aberrant, and overlap "lineage-specific" expression) in their application and interpretation.

DATA SOURCES.—

Literature review and the authors' personal practice experience were used. Several examples selected from the University Health Network (Toronto, Ontario, Canada) are illustrated.

CONCLUSIONS.—

The application of TF diagnostic immunohistochemistry has enabled pathologists to better assess the lineage/origin of primary and metastatic tumors. However, the awareness of potential pitfalls is essential to avoid misdiagnosis.

Diagnostic Utility of Thyroid Transcription Factor-1 in Ovarian Carcinoma and Its Relationship With Clinicopathologic Prognostic Parameters

Although thyroid transcription factor-1 (TTF-1) is considered a relatively sensitive and specific marker for lung and thyroid neoplasms, it can occasionally be expressed in other tumors. Few immunohistochemical studies have been conducted on TTF-1 expression in ovarian carcinomas with discrepant results. To date, only 1 study compared different TTF-1 clones in ovarian carcinoma. This study is designed to evaluate the expression of TTF-1 clones in ovarian carcinomas and investigate TTF-1 association with clinicopathologic prognostic parameters. A retrospective immunohistochemical study was conducted on 62 primary ovarian carcinomas and 15 normal ovarian tissues using 2 clones of TTF-1 antibody (SPT24 and 8G7G3/1). Nuclear expression of SPT24 and 8G7G3/1 clones of TTF-1 was detected in 17.7% and 3.2% of ovarian carcinomas, respectively. Positive cytoplasmic immunostaining of clone SPT24 was detected in 1.6% of cases. In contrast, normal ovarian tissue showed negative expression of both clones. A highly significant difference was observed between both clones regarding their sensitivity in ovarian carcinomas (P=0.004). A significant inverse relationship was observed between TTF-1 (SPT24 clone) expression and tumor stage (P=0.022). TTF-1 expression is not exclusive to lung and thyroid tissue. It is expressed in ovarian carcinomas where clone SPT24 is more sensitive than clone 8G7G3/1. TTF-1 might be of diagnostic utility in evaluating neoplasms of unknown primary origin as well as adenocarcinomas involving the lung in patients with a history of a gynecologic malignancy. Moreover, TTF-1 expression might be a good prognostic factor in ovarian carcinoma.

Loss of nuclear localization of thyroid transcription factor 1 and adverse outcomes in papillary thyroid cancer

Function of the thyroid follicular cell depends on nuclear expression of thyroid transcription factor 1 (TTF1). Regulation of this key protein regulating iodide transport is not well known, but its loss is linked to the most lethal of thyroid malignancies. We examined TTF1 nuclear expression in the context of adverse pathological features, disease recurrence, and BRAF status in papillary thyroid carcinomas with (n = 182) and without (n = 303) nodal metastases. Overall nuclear expression level of TTF1 was strong and diffuse in approximately 73%, whereas 27% exhibited lower levels or a paucity of nuclear staining. In the same cohort, approximately 59% exhibited the BRAF mutation. On univariate analysis, low levels of TTF1 nuclear expression was linked to vascular invasion, extrathyroidal extension, and nodal metastases. Multivariate analysis indicated that low levels of TTF1 were most strongly linked to nodal metastases and vascular invasion. Interestingly, TTF1 levels were not linked to the BRAF mutation. TTF1 staining alone predicted disease recurrence, but when combined with BRAF status, the 2 markers exhibited a more marked influence. Patients lacking the BRAF mutation and exhibiting normal levels of TTF1 exhibited very low levels of disease recurrence (11% at 10 years). Conversely, patient tumors with low levels of TTF1 and the BRAF mutation recurred in 31% of cases in the same time frame. The mixed expression of BRAF under varying levels of differentiation may explain, in part, the contradictory studies regarding the impact of BRAF mutations on patient prognosis and also indicates a complex genomic signature for dedifferentiated thyroid cancer.

Applications of Immunohistochemistry to Endocrine Pathology

The role of immunohistochemistry (IHC) in endocrine pathology is similar to that in other organ systems in that it can aid in the subclassification of tumors within an organ, confirm site of primary in metastatic disease, provide prognostic information, identify underlying genetic alterations, and predict response to treatment. Although most endocrine tumors do not require IHC to render a diagnosis, there are certain scenarios in which IHC can be extremely helpful. For example, in thyroid, IHC can be used to support tumor dedifferentiation, in the adrenal it can aid in the diagnosis of low-grade adrenocortical carcinomas, and in paragangliomas it can help identify tumors arising as part of an inherited tumor syndrome. This review will focus on the applications of IHC in tumors of the thyroid, parathyroids, adrenals, and paraganglia in adults.

Mouse Model of Poorly Differentiated Thyroid Carcinoma Driven by STRN-ALK Fusion

Chromosomal rearrangements of the ALK gene, which lead to constitutive activation of ALK tyrosine kinase, are found in various cancers. In thyroid cancers, ALK fusions, most commonly the STRN-ALK fusion, are detected in papillary thyroid cancer and with higher frequency in poorly differentiated and anaplastic thyroid cancers. Our aim was to establish a mouse model of thyroid-specific expression of STRN-ALK and to test whether this fusion drives the development of thyroid cancer with a propensity for dedifferentiation. Transgenic Tg-STRN-ALK mice with thyroglobulin-controlled expression of STRN-ALK were generated and aged with or without goitrogen treatment. Thyroids from these mice were subjected to histologic and immunohistochemical analysis. Transgenic mice with thyroid-specific expression of STRN-ALK developed poorly differentiated thyroid tumors by the age of 12 months in 22% of mice without goitrogen treatment and in 36% of mice with goitrogen treatment. Histologically and immunohistochemically, the tumors resembled poorly differentiated thyroid cancers in humans, demonstrating a solid growth pattern with sheets of round or spindle-shaped cells, decreased expression of thyroglobulin, and a tendency to lose E-cadherin. In this study, we report a novel mouse model of poorly differentiated thyroid cancer driven by the STRN-ALK oncogene with phenotypic features closely recapitulating human tumor, and with a more pronounced phenotype after additional thyroid-stimulating hormone stimulation.

Derivation of thyroid lymphoepithelial cysts from follicular cells

The pathogenesis of thyroid lymphoepithelial cysts is controversial, and two hypotheses have been proposed, namely derivation from branchial-derived remnants or from squamous metaplasia of the follicular cells. The aim of this study was to clarify the pathogenesis of thyroid lymphoepithelial cysts. We performed pathological and immunohistochemical examination of 21 thyroid lymphoepithelial cysts, 13 non-neoplastic squamous metaplasia samples without thyroid carcinoma, 13 solid cell nests, and 14 lateral cervical cysts. On ultrasound, half of thyroid lymphoepithelial cysts were interpreted as calcified nodules regardless of no calcification. Thyroid lymphoepithelial cysts and squamous metaplasia tended to be located in the central and lower portions of the thyroid, while solid cell nests were located in the upper and central portions (p < 0.05). In 95.2% of patients with thyroid lymphoepithelial cysts and all patients with squamous metaplasia, lesions were histologically associated with chronic thyroiditis forming lymph follicles. Hashimoto's disease was serologically confirmed in 18 patients with lymphoepithelial cysts (85.7%) and 10 patients with squamous metaplasia (76.9%). Immunohistochemically, lymphoepithelial cysts showed nuclear positivity for PAX8, thyroid transcription factor 1, and p63. One lateral cervical cyst (7.1%) showed positive staining for PAX8, while solid cell nests were PAX8-negative. In three (14.3%) cases of thyroid lymphoepithelial cysts, squamous cells located on the superficial layer were focally and weakly positive for CEA. We concluded that thyroid lymphoepithelial cysts originate from follicular cells and are unrelated to solid cell nests and lateral cervical cysts arising from branchial-derived remnants.

The Correlation between TTF-1 Immunoreactivity and the Occurrence of Lymph Node Metastases in Patients with Lung Cancer

Aims and background

Thyroid transcription factor (TTF-1) is a tissue-specific transcription factor expressed in the epithelial cells of thyroid and lung. The aim of this study was to evaluate the relationship between the expression of TTF-1 and clinicopathological parameters in pulmonary adenocarcinoma and adenosquamous carcinoma.

Methods

Resection material of pneumonectomies and lobectomies of 39 patients was retrospectively examined. Twenty-eight patients were diagnosed with adenocarcinoma and 11 with adenosquamous carcinoma. Tumors were classified into 3 groups: a strongly positive group (++) with ‡50% tumor cells positive for TTF-1; a weakly positive group (+) with 1–49% positive tumor cells; and a negative group (-) with less than 1% or no positive tumor cells. Analysis was performed with Kaplan-Meier estimates and log-rank tests.

Results

Staining for TTF-1 was negative in 10 cases. There was focal staining in 9 cases, while there was diffuse staining in 20 (51%) cases out of 39, and 15 (75%) of these were adenocarcinomas. There was a statistically significant association between TTF-1 and lymph node metastases (P = 0.029). No relationship was found between TTF-1 positivity and disease-free and overall survival.

Conclusions

TTF-1 expression may be a predictor of lymph node metastases. Additional work in a larger group of patients is needed to better assess the utility of this marker.

Clinical, pathological and genetic features of anaplastic and poorly differentiated thyroid cancer: A single institute experience

Anaplastic (ATC) and poorly differentiated thyroid cancer (PDTC) are very aggressive cancers whose histological diagnosis is not always straightforward. Clinical, pathological and genetic features may be useful to improve the identification of these rare histotypes. In the present study the clinical, pathological and genetic features of two groups of ATC (n=21) and PDTC (n=21) patients were analyzed. Clinical data were retrieved from a computerized database. The oncogenic profiles were studied using the Sanger sequencing method of a selected series of oncogenes and/or tumor suppressor genes known to be altered in these tumors. The presence of macrophages in both series of tissues was evaluated by immunohistochemistry. Patients with ATC were older and affected by a more advanced disease at diagnosis than those with PDTC. The median survival was significantly shorter in ATC compared with PDTC patients (P=0.0014). ATC showed a higher prevalence of TP53 and TERT mutations (10/21, 47.6% and 9/21, 42.8%, respectively) while TERT and BRAF mutations were the most prevalent in the PDTC group (7/21, 33.3% and 4/23, 19% respectively). Genetic heterogeneity (i.e., >2 mutations) was more frequent in ATC (10/21, 28.6%) compared with in PDTC (3/21, 4.7%) (P=0.03). Macrophages were more frequently present in ATC, particularly in those cases with TP53 mutations. In conclusion, these data indicate that ATC and PDTC may be characterized by different clinical, pathological and genetic profiles. In particular ATC, but not PDTC, were positive for TP53 and PTEN alterations. Complex mutations were also found in ATC but not in PDTC. Moreover, genetic heterogeneity was more frequent in ATC than PDTC. Finally, TP53 mutation and the accumulation of several mutations correlated with a shorter survival time.

Identification of metastatic papillary thyroid carcinoma in FNA specimens using thyroid peroxidase immunohistochemistry

INTRODUCTION

We evaluated immunohistochemical staining for thyroid peroxidase (TPO), a glycoprotein found in the apical plasma membrane of thyroid follicular cells, as a marker for metastatic PTC in FNA samples and compared results with thyroglobulin (Tg) and thyroid transcription factor 1 (TTF1) staining.

METHODS

Cell block sections prepared from 100 FNA specimens were stained with a rabbit monoclonal antibody to TPO (EP159). The FNAs included 64 metastatic malignancies from non-thyroid primary sites, including 18 lung, and 36 cases of thyroid tumours (29 PTC, six cases of medullary thyroid carcinoma and one thyroid anaplastic carcinoma). Thyroid tumours were stained with TTF1 and Tg in addition to TPO. All cases of metastatic lung carcinoma also had TTF-1 staining results.

RESULTS

TPO staining was negative in all non-thyroid malignancies. Ninety percent (26/29) of PTC were positive. All positive cases showed strong cytoplasmic staining, although 54% (14/26) showed positivity in less than half of the cells. By comparison, Tg staining of TPC cases was present in 62% and TTF-1 in 100%. In addition to showing higher sensitivity, interpretation of staining results with TPO was generally easier with than Tg. All metastatic lung adenocarcinomas were positive for TTF-1 and TPO negative. The six medullary cancers showed positivity in 17%, 0% and 83% with TPO, Tg and TTF-1, respectively.

CONCLUSIONS

TPO (mAb EP159) may be a useful addition to immunohistochemical panels for FNA specimens where metastatic PTC is a consideration, particularly in cases where metastatic lung carcinoma features in the differential diagnosis.

Case report: Diffuse metastatic infiltration of the thyroid by esophageal adenocarcinoma mimicking non-neoplastic thyroid disease

We report a patient who suffered from esophageal cancer that metastasized to the thyroid. There are only a handful of cases of esophageal cancer with metastases to the thyroid reported in the literature. To our knowledge, this is the first with a diffusely infiltrative pattern (the others were focal masses/nodules). This diffusely infiltrative pattern of metastatic disease is important for radiologists to be aware of because it is particularly difficult to detect and is not characteristically neoplastic by pattern. A diffuse parenchymal abnormality that is bilaterally symmetric is more commonly associated with non-neoplastic diffuse thyroid disease, such as autoimmune thyroid diseases (eg, Graves' disease). As such, in addition to the more common non-neoplastic differential diagnoses associated with diffuse thyroid disease, a diffuse thyroid parenchymal abnormality in a patient with a history of esophageal carcinoma should raise the question of diffuse metastatic infiltration.

Solitary Thyroid Metastasis of Clear Cell Renal Carcinoma: Case Report

Metastases to the thyroid gland represent a rare event. Malignancies that most frequently metastasize to the thyroid vary between clinical and autopsy studies and by geographic area. In Western countries, renal carcinoma has been recorded as a frequent source of thyroid metastases. We report the case of a 66-year-old man with a thyroid metastasis from clear cell renal carcinoma and discuss its clinical, pathological and imaging features.

KIF5B/RET Rearrangement in a Carcinoma of the Thyroid Gland: A Case Report of a Fatal Disease

BACKGROUND

The diffuse sclerosing variant of papillary thyroid cancer (DSV-PTC) is a rare variant of papillary thyroid cancer (PTC) with different clinicopathological features compared with conventional PTC.

CASE

An advanced DSV-PTC was diagnosed in a 39-year-old man. The radioiodine posttherapeutic whole-body-scan showed only an uptake in the central neck, whereas the computerized tomography showed multiple latero-cervical and mediastinum lymph node metastases, a single and spiculated lung lesion and multiple bilateral cerebellum metastases. The patient died after 6 months from the initial diagnosis. The histological revision of the thyroid tumor confirmed the diagnosis of DSV-PTC, and its molecular analysis revealed a KIF5B/RET rearrangement that, until now, was described only in a minority of lung adenocarcinoma. Other 18 cases of DSV-PTC were then studied for the presence of KIF5B/RET rearrangement, but all of them were negative.

CONCLUSIONS

This was a case of DSV-PTC positive for KIF5B/RET rearrangement, but considering that this alteration has been described only in lung adenocarcinoma and that the clinical course was more typical of lung carcinoma, we cannot completely rule out the possibility that this was a metastatic lesion from a lung tumor mimicking a DSV-PTC. As an alternative, we can also hypothesize that this was a case of fusion of two tumoral tissues deriving from a DSV-PTC and a metastasis of a KIF5B/RET positive lung adenocarcinoma. The question of whether the molecular findings, particularly when specifically reported only in some subtypes of human tumors, can overcome the morphological diagnosis is a matter of discussion.

A Concise Atlas of Thyroid Cancer Next-Generation Sequencing Panel ThyroSeq v.2

The next-generation sequencing technology allows high out-put genomic analysis. An innovative assay in thyroid cancer, ThyroSeq® was developed for targeted mutation detection by next generation sequencing technology in fine needle aspiration and tissue samples. ThyroSeq v.2 next generation sequencing panel offers simultaneous sequencing and detection in >1000 hotspots of 14 thyroid cancer-related genes and for 42 types of gene fusions known to occur in thyroid cancer. ThyroSeq is being increasingly used to further narrow the indeterminate category defined by cytology for thyroid nodules. From a surgical perspective, genomic profiling also provides prognostic and predictive information and closely relates to determination of surgical strategy. Both the genomic analysis technology and the informatics for the cancer genome data base are rapidly developing. In this paper, we have gathered existing information on the thyroid cancer-related genes involved in the initiation and progression of thyroid cancer. Our goal is to assemble a glossary for the current ThyroSeq genomic panel that can help elucidate the role genomics play in thyroid cancer oncogenesis.

Mixed Neuroendocrine-Nonneuroendocrine Neoplasms (MiNENs): Unifying the Concept of a Heterogeneous Group of Neoplasms

The wide application of immunohistochemistry to the study of tumors has led to the recognition that epithelial neoplasms composed of both a neuroendocrine and nonneuroendocrine component are not as rare as traditionally believed. It has been recommended that mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are classified as only those in which either component represents at least 30 % of the lesion but this cutoff has not been universally accepted. Moreover, since their pathogenetic and clinical features are still unclear, mixed neuroendocrine-nonneuroendocrine epithelial neoplasms are not included as a separate clinicopathological entity in most WHO classifications, although they have been observed in virtually all organs. In the WHO classification of digestive tumors, mixed neuroendocrine-nonneuroendocrine neoplasm is considered a specific type and is defined as mixed adenoneuroendocrine carcinoma, a definition that has not been accepted for other organs. In fact, this term does not adequately convey the morphological and biological heterogeneity of digestive mixed neoplasms and has created some misunderstanding among both pathologists and clinicians. In the present study, we have reviewed the literature on mixed neuroendocrine-nonneuroendocrine epithelial neoplasms reported in the pituitary, thyroid, nasal cavity, larynx, lung, digestive system, urinary system, male and female genital organs, and skin to give the reader an overview of the most important clinicopathological features and morphological criteria for diagnosing each entity. We also propose to use the term "mixed neuroendocrine-nonneuroendocrine neoplasm (MiNEN)" to define and to unify the concept of this heterogeneous group of neoplasms, which show different characteristics mainly depending on the type of neuroendocrine and nonneuroendocrine components.

Metastatic Papillary Thyroid Carcinoma with Multifocal Synchronous Transformation to Anaplastic Thyroid Carcinoma

Papillary thyroid carcinoma is a common malignancy to affect the thyroid and is typified by a nonaggressive nature and low rates of mortality. In contrast, anaplastic thyroid carcinoma is the most aggressive thyroid malignancy with a mortality rate of nearly 90% and survival typically of only six months after the diagnosis is made. The transformation of papillary thyroid carcinoma to anaplastic thyroid carcinoma is well documented in the literature but is uncommon and in most instances is reported as a case report or small series only. Transformation of papillary thyroid carcinoma to anaplastic thyroid carcinoma usually takes place in the thyroid itself or in the adjacent lymph nodes. Only on rare occasions does a transformation occur in a papillary thyroid carcinoma metastasis outside of these locations. In the present case report and subsequent discussion we highlight an unusual case of PTC with transformation to anaplastic thyroid carcinoma, which is shown to involve numerous locations to include near total lung parenchyma obliteration. We also discuss the differential diagnostic challenges when faced with a thyroid malignancy that is negative for thyroglobulin.

Granular Cell Tumor of the Thyroid: A Case Report

We report a rare case of granular cell tumor (GCT) arising within the thyroid parenchyma. The differential diagnosis of GCT in thyroid includes all oncocytic/Hürthle cell lesions of the thyroid, medullary carcinoma and metastasis. The classic histomorphologic features and immunohistochemistry are helpful in arriving at the correct diagnosis.

Comparison of Clinical and Ultrasonographic Features of Poorly Differentiated Thyroid Carcinoma and Papillary Thyroid Carcinoma

Background:

The clinical behavior and management of poorly differentiated thyroid carcinoma (PDTC) are very different from papillary thyroid carcinoma (PTC). By comparing the clinical and ultrasonographic features between the two tumors, we proposed to provide more possibilities for recognizing PDTC before treatment.

Methods:

The data of 13 PDTCs and 39 age- and gender-matched PTCs in Peking Union Medical College Hospital between December 2003 and September 2013 were retrospectively reviewed. The clinical and ultrasonic features between the two groups were compared.

Results:

The frequencies of family history of carcinoma, complication with other thyroid lesions, lymph node metastases, recurrent laryngeal nerve injuries, and distant metastases were higher in PDTCs (30.8%, 61.6%, 69.2%, 23.1%, and 46.2%, respectively) than those in PTCs (2.6%, 23.1%, 25.6%, 2.6%, and 2.6%, respectively) (P < 0.05). The mortality rate of PDTCs was greatly higher than PTCs (P < 0.01). Conventional ultrasound showed that the size of PDTCs was larger than that of PTCs (3.1 ± 1.9 cm vs. 1.7 ± 1.0 cm). Clear margins and rich and/or irregular blood flow were found in 92.3% of PDTCs, which differed substantially from PTCs (51.7% and 53.8%, respectively) (P < 0.05).

Conclusions:

PDTC is more aggressive and its mortality rate is higher than PTCs. Accordingly, more attention should be given to suspicious thyroid cancer nodules that show large size, regular shape, and rich blood flow signals on ultrasound to exclude the possibility of PDTCs.

Practical Applications in Immunohistochemistry: Carcinomas of Unknown Primary Site

CONTEXT

-Identification of the site of origin of carcinoma of unknown primary using immunohistochemistry is a frequent requirement of anatomic pathologists. Diagnostic accuracy is crucial, particularly in the current era of targeted therapies and smaller sample sizes.

OBJECTIVES

-To provide practical guidance and suggestions for classifying carcinoma of unknown primary using both proven and new antibodies, as well as targeting panels based on integration of morphologic and clinical features.

DATA SOURCES

-Literature review, the authors' practice experience, and authors' research.

CONCLUSIONS

-With well-performed and interpreted immunohistochemistry panels, anatomic pathologists can successfully identify the site of origin of carcinoma of unknown primary. It is crucial to understand not only the diagnostic uses of the many available antibodies but also the potential limits and pitfalls.

Application of Immunohistochemistry in Thyroid Pathology

Context

Accurate classification of follicular-patterned thyroid lesions is not always an easy task on routine surgical hematoxylin-eosin–stained or cytologic fine-needle aspiration specimens. The diagnostic challenges are partially due to differential diagnostic criteria that are often subtle and subjective. In the past decades, tremendous advances have been made in molecular gene profiling of tumors and diagnostic immunohistochemistry, aiding in diagnostic accuracy and proper patient management.

Objective

To evaluate the diagnostic utility of the most commonly studied immunomarkers in the field of thyroid pathology by review of the literature, using the database of indexed articles in PubMed (US National Library of Medicine) from 1976–2013.

Data Sources

Literature review, authors' research data, and personal practice experience.

Conclusions

The appropriate use of immunohistochemistry by applying a panel of immunomarkers and using a standardized technical and interpretational method may complement the morphologic assessment and aid in the accurate classification of difficult thyroid lesions.

Cutaneous metastasis of medullary carcinoma thyroid masquerading as subcutaneous nodules anterior chest and mandibular region

Cutaneous metastasis of underlying primary malignancies can present to dermatologist with chief complaints of cutaneous lesions. The underlying malignancy is generally diagnosed much later after a complete assessment of the concerned case. Medullary carcinoma thyroid (MCT) is a relatively uncommon primary neoplasia of the thyroid. Very few cases presenting as cutaneous metastases of MCT have been reported in the literature. Most of the cases which have been reported are of the papillary and the follicular types. We here report a case of a patient who presented in the dermatology clinic with the primary complaint of multiple subcutaneous nodules in anterior chest wall and left side of body of mandible. By systematic application of clinical and diagnostic skills these nodules were diagnosed as cutaneous metastasis of MCT bringing to the forefront a history of previously operated thyroid neoplasm. So clinically, the investigation of a flesh coloured subcutaneous nodule, presenting with a short duration, particularly in scalp, jaw, or anterior chest wall should include possibility of metastastic deposits. A dermatologist should keep a possibility of an internal organ malignancy in patients while investigating a case of flesh coloured subcutaneous nodules, presenting with short duration. A systematic application of clinical and diagnostic skills will eventually lead to such a diagnosis even when not suspected clinically at its primary presentation. A prompt and an emphatic diagnosis and treatment will have its bearing on the eventual outcome in all these patients.

A rare coexistence of non-functional adrenocortical carcinoma and multicentric papillary thyroid microcarcinoma: a case report

Introduction

In this report, we describe a rare case of papillary thyroid carcinoma with adrenocortical carcinoma without excess hormone production.

Case presentation

A 40-year-old Turkish man was admitted to our institution with a large left adrenal mass that was identified during the work-up for shortness of breath. The patient did not have specific signs and symptoms of hormone excess. The mass was removed surgically. The pathological findings were consistent with adrenocortical carcinoma. The patient was also found to have a multicentric papillary thyroid microcarcinoma.

Conclusion

Most adrenocortical carcinomas and papillary thyroid carcinomas are sporadic; however, the occurrence of two different endocrine neoplasms during the same period of time is a rare situation, but it is possible, as in our patient. When an endocrine tumor is diagnosed, endocrinologists must be consider the possibility of the existence of another endocrine tumor.

Value of thyroid transcription factor-1 immunostaining in tumor diagnosis: a review and update

Thyroid transcription factor-1 (TTF-1) is a tissue-specific transcription factor that plays a critical role in the normal development of embryonic epithelial cells of the thyroid and lung. Because TTF-1 expression is highly restricted to epithelial tumors arising in these organs, it is, at present, one of the immunohistochemical markers most commonly used to assist in the differential diagnosis of carcinomas of the lung and thyroid. Recent studies, however, have reported that TTF-1 is not as specific for lung and thyroid carcinomas as was previously thought as it can be found to be expressed, although much less frequently, in some carcinomas arising in other organs, such as the ovaries, endometrium, colon, and breast, as well as in some tumors of the central nervous system. Even though this unexpected TTF-1 positivity has been reported more frequently with the recently available SPT24 anti-TTF-1 monoclonal antibody, it has also been shown to occur with the commonly used 8G7G3/1 clone, albeit in a lower percentage of cases. Despite these findings, TTF-1 remains a very useful immunohistochemical marker in diagnostic pathology.

Exclusive Endoscopic Resection of Nasopharyngeal Papillary Adenocarcinoma via Combined Transnasal and Transoral Approach

Low grade nasopharyngeal papillary adenocarcinoma (LGNPPA) is an extremely rare variant of nasopharyngeal cancer, which exhibits distinct clinicopathological characteristics. Surgical resection has been regarded as the principal treatment. For this, transpalatal or transfacial approach has been classically used for exposure of the field. Up for now, there has been no report on applying endoscopic approach for this disease, which could be an effective alternative to minimize possible morbidities of palatotomy or maxillotomy. Endoscopic approach can be justified considering narrow extent and indolent behavior of LGNPPA. We report a patient with LGNPPA, which was successfully resected exclusively by endoscopic visualization. Our case exhibited narrow-based exophytic features with compatible immunopathologic profiles of LGNPPA. Exclusive endoscopic resection can be effective and less-morbid modality for this rare disease as in this case.

Anaplastic thyroid cancer: molecular pathogenesis and emerging therapies

Anaplastic thyroid cancer (ATC) is a rare malignancy. While external beam radiation therapy has improved locoregional control, the median survival of approximately 4 months has not changed in more than half a century due to uncontrolled systemic metastases. The objective of this study was to review the literature in order to identify potential new strategies for treating this highly lethal cancer. PubMed searches were the principal source of articles reviewed. The molecular pathogenesis of ATC includes mutations in BRAF, RAS, catenin (cadherin-associated protein), beta 1, PIK3CA, TP53, AXIN1, PTEN, and APC genes, and chromosomal abnormalities are common. Several microarray studies have identified genes and pathways preferentially affected, and dysregulated microRNA profiles differ from differentiated thyroid cancers. Numerous proteins involving transcription factors, signaling pathways, mitosis, proliferation, cell cycle, apoptosis, adhesion, migration, epigenetics, and protein degradation are affected. A variety of agents have been successful in controlling ATC cell growth both in vitro and in nude mice xenografts. While many of these new compounds are in cancer clinical trials, there are few studies being conducted in ATC. With the recent increased knowledge of the many critical genes and proteins affected in ATC, and the extensive array of targeted therapies being developed for cancer patients, there are new opportunities to design clinical trials based upon tumor molecular profiling and preclinical studies of potentially synergistic combinatorial novel therapies.

Lung adenocarcinoma with micropapillary component presenting with metastatic scrotum tumor and cancer-to-cancer metastasis: A case report

A 54-year-old man was admitted to the hospital presenting with a 3-month history of sclerosing dermal lesion in the external genitalia. A scrotal skin biopsy revealed a poorly-differentiated adenocarcinoma, immunohistochemically positive for cytokeratin 7 (CK7) and for thyroid transcription factor 1 (TTF-1), and negative for CK20. One month after admission, he died of respiratory failure. At autopsy, a consolidating lesion with vague margin was noted in the left lung as well as a well-circumscribed nodule in the right lobe of the thyroid. Histopathologically, pulmonary lesion was adenocarcinoma with a micropapillary component. On the other hand, thyroid tumor was diagnosed as a follicular variant of papillary carcinoma with foci of micropapillary adenocarcinoma. Positive immunohistochemistry for surfactant protein on micoropapillary component was useful to confirm that micropapillary component was of lung adenocarcinoma origin.

Application of immunohistochemistry to thyroid neoplasms

CONTEXT

Thyroid lesions with nodular architecture and follicular pattern of growth often pose difficulties in accurate diagnosis during the assessment of cytologic and histologic specimens. The diagnosis of follicular neoplasm on cytology or of follicular tumor of uncertain malignant potential on histology is likely to cause confusion among clinicians and delay effective management of these lesions. Occasionally, thyroid tumors represent unusual or metastatic lesions and their accurate diagnosis requires immunohistochemical confirmation.

OBJECTIVE

To review the literature on the applications of immunohistochemistry in the differential diagnosis of thyroid tumors.

DATA SOURCES

Relevant articles indexed in PubMed (National Library of Medicine) between 1976 and 2006.

CONCLUSIONS

Our review supports the use of ancillary techniques involving a panel of antibodies suitable for immunohistochemistry and molecular analysis in the assessment of thyroid nodules. These tools can improve diagnostic accuracy when combined with standard morphologic criteria.

Herpetiform cutaneous metastases from transitional cell carcinoma of the urinary bladder: immunohistochemical analysis

The case of an 83-year-old woman with an uncommon presentation of cutaneous metastases from muscle-invasive transitional cell carcinoma of the urinary bladder is reported. The band-like eruption of the metastatic lesion can often be misdiagnosed and treated initially as herpes zoster. A detailed immunohistochemical analysis is also described to differentiate metastatic lesions from other sources.

Positive immunostaining for thyroid transcription factor-1 in primary and metastatic colonic adenocarcinoma: a note of caution

Immunohistochemistry for thyroid transcription factor-1 (TTF-1) is considered an important ancillary technique for distinguishing primary pulmonary adenocarcinomas from metastases. A case of metastatic colonic adenocarcinoma in a bronchial biopsy specimen that showed focal positive nuclear staining for TTF-1 is reported here. The primary colonic adenocarcinoma was retrieved from the file and immunostaining also showed focal nuclear positivity for TTF-1. This confirmed the morphological and clinical impression of colonic metastases in the bronchial biopsy specimen. To investigate this apparent aberrant TTF-1 expression, further sections from primary colonic adenocarcinoma were immunostained for TTF-1 using the SPT24 antibody clone. Three of the six cases studied showed focal nuclear positivity with the SPT24 clone. All six cases were subsequently shown to be negative with the 8G7G1 clone. It is concluded that the SPT24 antibody to TTF-1 may show focal nuclear positivity in adenocarcinomas of colorectal origin such that focal staining in small biopsy specimens should be interpreted with caution.

Thyroid transcription factor 1 expression in cystic lesions of the neck: an immunohistochemical investigation of thyroglossal duct cysts, branchial cleft cysts and metastatic papillary thyroid cancer

Cervical metastases of papillary thyroid cancer (PTC) are of particular diagnostic importance, because they can mimic branchiogenic cysts clinically and histopathologically when undergoing cystic change. Immunohistochemical stains for thyroid transcription factor 1 (TTF-1), which are positive in thyroid cancers, are reported to be valuable in establishing diagnosis. However, TTF-1 may also be expressed in dysontogenetic cysts of the neck. Therefore, immunohistochemical stains for TTF-1 and thyroglobulin (TG) were performed on each of the ten thyroglossal duct cysts, branchial cleft cyst and lymph node metastasis of PTC. Five in ten cases of thyroglossal duct cysts were positive for TTF-1, but all were negative for TG. One of the ten branchial cleft cysts stained for TTF-1, while all cases were negative for TG. All ten cases of lymph node metastases of PTC showed positive for TTF-1, nine of which were positive for TG. Since a positive immunostaining for TTF-1 in cystic lesions of the neck was not only found in metastases of PTC, but also in non-malignant branchiogenic cysts, additional investigations, e.g. an immunostaining for TG, should be added in difficult cases.