Expression of renal cell carcinoma-associated markers erythropoietin, CD10, and renal cell carcinoma marker in diffuse malignant mesothelioma and metastatic renal cell carcinoma

Guidelines for Pathologic Diagnosis of Mesothelioma: 2023 Update of the Consensus Statement From the International Mesothelioma Interest Group

CONTEXT.—

Mesothelioma is an uncommon tumor that can be difficult to diagnose.

OBJECTIVE.—

To provide updated, practical guidelines for the pathologic diagnosis of mesothelioma.

DATA SOURCES.—

Pathologists involved in the International Mesothelioma Interest Group and others with expertise in mesothelioma contributed to this update. Reference material includes peer-reviewed publications and textbooks.

CONCLUSIONS.—

There was consensus opinion regarding guidelines for (1) histomorphologic diagnosis of mesothelial tumors, including distinction of epithelioid, biphasic, and sarcomatoid mesothelioma; recognition of morphologic variants and patterns; and recognition of common morphologic pitfalls; (2) molecular pathogenesis of mesothelioma; (3) application of immunohistochemical markers to establish mesothelial lineage and distinguish mesothelioma from common morphologic differentials; (4) application of ancillary studies to distinguish benign from malignant mesothelial proliferations, including BAP1 and MTAP immunostains; novel immunomarkers such as Merlin and p53; fluorescence in situ hybridization (FISH) for homozygous deletion of CDKN2A; and novel molecular assays; (5) practical recommendations for routine reporting of mesothelioma, including grading epithelioid mesothelioma and other prognostic parameters; (6) diagnosis of mesothelioma in situ; (7) cytologic diagnosis of mesothelioma, including use of immunostains and molecular assays; and (8) features of nonmalignant peritoneal mesothelial lesions.

Prognostic role of CD74, CD10 and Ki-67 immunohistochemical expression in patients with diffuse malignant peritoneal mesothelioma: a retrospective study

BACKGROUND

Diagnosis and treatment of diffuse malignant peritoneal mesothelioma (DMPM) are still challenging. The aim of the present study was to explore the correlation between CD74, CD10, Ki-67 and clinicopathological parameters, and identify independent prognostic factors of DMPM.

METHODS

Seventy patients with pathologically proven DMPM were retrospectively reviewed. The expression of CD74, CD10 and Ki-67 in peritoneal tissues was detected by immunohistochemical analysis using standard avidin biotin complex (ABC) immunostaining technique. Kaplan-Meier survival analysis and multivariate Cox regression analyses were performed to assess prognostic factors. The nomogram based on the Cox hazards regression model was established. C-index and calibration curve were performed to evaluate the accuracy of nomogram models.

RESULTS

The median age of DMPM was 62.34 years, and the male-to-female ratio was 1: 1.80. CD74 expression was identified in 52 (74.29%) of 70 specimens, CD10 in 34 (48.57%) specimens, and higher Ki-67 in 33(47.14%) specimens. CD74 was negatively associated with asbestos exposure(r = -0.278), Ki-67(r = -0.251) and TNM stage(r = -0.313). All patients were effectively followed up in the survival analysis. Univariate analysis revealed that PCI, TNM stage, treatment, Ki-67, CD74 and ECOG PS were associated with DMPM prognosis. CD74 (HR = 0.65, 95%Cl:0.46-0.91, P = 0.014), Ki-67(HR = 2.09, 95%Cl:1.18-3.73, P = 0.012),TNM stage (HR = 1.89, 95%Cl:1.16-3.09, P = 0.011), ECOG PS(HR = 2.12, 95%Cl:1.06-4.25, P = 0.034), systemic chemotherapy (HR = 0.41, 95%Cl:0.21-0.82, P = 0.011) and intraperitoneal chemotherapy (HR = 0.34, 95%Cl:0.16-0.71, P = 0.004) were independent predictors by multivariate Cox analysis. The C‑index of the nomogram for predicting overall survival (OS) was 0.81. The OS calibration curve showed good agreement between nomogram-predicted and observed survival.

CONCLUSIONS

CD74, Ki-67, TNM stage, ECOG PS and treatment were independent factors affecting prognosis of DMPM. Reasonable chemotherapy treatment might improve the prognosis of patients. The proposed nomogram was a visual tool to effectively predict the OS of DMPM patients.

State-of-the-art cytology of pleural fluid, focusing on the diagnosis of mesothelioma

Mesothelioma has always been a challenging diagnosis to render in body cavity cytology samples. This review is a timely update on pleural fluid cytology and ancillary studies that should be considered in the diagnosis of mesothelial proliferations, specifically mesotheliomas. Information about new diagnostic approaches and ancillary studies in mesothelioma was obtained from the peer-reviewed literature and the authors' experiences. Although the morphological diagnosis of mesothelioma is fraught with numerous challenges given the overlap with other diagnostic entities, there are a variety of immunohistochemical and fluorescence in situ hybridization studies available to help in determining mesothelial origin and in distinguishing malignant proliferations from the more common benign or reactive mesothelial proliferations. Although ancillary studies can be helpful, there are important pitfalls to be aware of when interpreting these cases, and this review highlights some of the challenges that require caution.

A New CD10 Antibody Inhibits the Growth of Malignant Mesothelioma

Malignant mesotheliomas (MMs) are aggressive therapy-resistant tumors that generally have a poor prognosis. We previously reported the establishment of four new monoclonal antibodies (mAbs) for the diagnosis and treatment of MM. In this report, we characterized one of these antibodies, JMAM-1. The molecules whose antibodies were calibrated were picked up, transfected assuming CD10, and elucidated by fluorescence activated cell sorter. Survival experiments were performed using tumor-bearing mice model. JMAM-1 mAb was found to bind with CD10 antigen. The Kaplan–Meier survival curve showed a small but prolonged survival effect. JMAM-1 mAb-treated MSTO-211H cells showed increased cell cycle arrest involved by cyclin-dependent-kinase. JMAM-1 antibody has cytostatic effect and may be a candidate for the treatment of MM. Among mesothelioma, CD10-positive cases have been reported to have a poorer prognosis than negative cases, which can be used as a tool for diagnosis.

Pleural mesothelioma classification update

The 2015 WHO classification of pleural mesotheliomas includes three major histologic subtypes-epithelioid, sarcomatoid, and biphasic. Recent genomic data has supported the need for a more granular and clinically valid classification beyond the three current subtypes. Because of tumor rarity and overlapping histologic features with other tumor types, diagnostic immunohistochemical work up is essential component in establishing the final diagnosis of mesothelioma. The use of BAP1 and CDKN2A/MTAP improves the diagnostic sensitivity of effusion specimens and are valuable in establishing the diagnosis of epithelioid mesothelioma. The major change in the forthcoming WHO classification is the inclusion of mesothelioma in situ as a diagnostic category. In this review, we discuss recently proposed changes in the histologic classification of pleural mesothelioma, differential diagnosis, and importance of ancillary diagnostic studies.

Ocular adnexal metastases from renal cell carcinoma: An update and comprehensive literature review

PURPOSE:

The purpose of this study was to review the clinical presentation, systemic work-up, and outcomes of all previously reported ocular adnexal (OA) metastases from renal cell carcinoma (RCC).

METHODS:

This was a literature review. PubMed and Google Scholar databases were searched for all well-documented cases of OA metastases from RCC.

RESULTS:

Final analysis identified 44 patients with either biopsy-confirmed (41/44, 93%) or treatment response-documented (3/44, 6%) OA metastases from RCC. Thirty-four (77%) patients were male. The median age was 60 years (mean: 60, range: 22–87 years). The most common presenting signs were proptosis (19/44, 43%) and OA mass (14/44, 32%). Metastases most frequently involved the orbital bones (10/44, 23%) and adjacent extraconal fat, extending from the sinonasal tract in 7/10 (70%) of these cases. OA metastases were initial manifestation of RCC in 18/44 (41%) patients. At the time of primary tumor diagnosis, 22 of 30 (73%) patients had American Joint Committee on Cancer Stage IV disease with metastases to 2 or more sites in 13 (57%) patients. Seventeen of 42 (40%) patients underwent local therapy only, which most commonly included excision/exenteration with margin control (10/17, 59%). Twenty-five of 42 (60%) patients had systemic therapy, which included biologic agents and chemotherapy. The absolute 5-year survival rate was 66% with significantly improved survival in patients reported after 2006 (92% vs. 42%, P = 0.04) and in those with isolated OA metastases (100% vs. 27%, P = 0.02) at 30 months.

CONCLUSION:

Although RCC metastases to OA occur in a setting of advanced disease, the recent advances in diagnostic modalities and targeted therapies resulted in improved survival.

Metastatic sarcomatoid renal cell carcinoma manifesting as a subcutaneous soft tissue mass

Metastases from visceral malignancies to subcutaneous soft tissues are relatively rare and their diagnosis requires a high level of suspicion. It is even more challenging if a metastatic lesion shows non-specific high-grade spindle cell morphology overlapping with various primary cutaneous and soft tissue tumors. We describe a unique case of subcutaneous metastasis of sarcomatoid renal cell carcinoma which was the first manifestation of the occult malignancy. The patient had a history of lipomas and dysplastic nevi and presented with an upper back mass. The mass, located superficially within the subcutis, was composed of atypical spindle cells arranged in a storiform pattern. By immunohistochemistry, the tumor cells were strongly diffusely positive for cytokeratin AE1/AE3 and vimentin and negative for Melan-A, S-100 protein, SOX10, melanoma cocktail, epithelial membrane antigen (EMA), p63, CK7, CK18, CK20, smooth muscle actin (SMA), desmin, CD34, TTF-1, CD21, CD99 and bcl-2. Scattered tumor cells were positive for MDM2 immunostain, but MDM2 amplification was not detected using fluorescent in situ hybridization (FISH). Co-expression of cytokeratin and vimentin by the tumor raised the possibility of metastatic renal cell carcinoma and positivity of the tumor for PAX8 supported this hypothesis. A large renal mass was detected radiologically and the subsequent nephrectomy specimen showed high-grade clear cell renal cell carcinoma with sarcomatoid features.

Morphologic Features Suggestive of Endometriosis in Nondiagnostic Peritoneal Biopsies

Endometriosis is a common disorder that causes significant morbidity from dysmenorrhea, pelvic pain, and subfertility. Establishment of a definitive diagnosis has important therapeutic implications; however, only approximately 50% of biopsies of laparoscopically suspicious areas provide a diagnosis of endometriosis. Histologic criteria for diagnosis require the presence of endometrial glands or endometrial-type stroma. We hypothesize that other frequently present, but nondiagnostic, histologic features of endometriosis suggest its presence in patients with nondiagnostic peritoneal biopsies. We performed a retrospective clinicopathologic study of morphologic and immunohistochemical features that may improve the histologic diagnosis of endometriosis on laparoscopic peritoneal biopsies. We compared diagnostic (n=88) and nondiagnostic (n=54) peritoneal biopsies from pathologically confirmed endometriosis cases with negative peritoneal biopsies (n=84) from early-stage gynecologic cancer cases. Statistical analysis utilized the Fisher exact test. Multiple morphologic features were significantly increased in nondiagnostic biopsies from patients with endometriosis in comparison with those from negative controls, including foamy macrophages (P=0.0001) and submesothelial stromal clusters (SSCs) (P=0.0008). SSCs ranged from subtle aggregates of spindle cells to nodules of whorled spindle cells with small vessels and extravasated red blood cells resembling stromal endometriosis. Immunohistochemical studies confirmed that ER and CD10-positive SSCs were present in a greater proportion of both nondiagnostic and diagnostic peritoneal biopsies and at a greater number of lesions per biopsy. The overall histologic detection rate of peritoneal biopsies for endometriosis was 62.0%, and inclusion of SSCs with or without foamy macrophages in the diagnostic criteria appreciably increased this rate to between 72.5% and 76.8%. We describe SSCs, which appear to be an early or less developed form of stromal endometriosis, and, when included in the diagnostic criteria, improve the histologic detection rate of endometriosis in peritoneal biopsies.

Tumoral CD10 expression correlates with aggressive histology and prognosis in patients with malignant pleural mesothelioma

BACKGROUND

Currently, tumor-node-metastasis stage and histologic type are the established prognostic factors for malignant pleural mesothelioma, whereas no prognostic markers have been established for clinical practice. We investigated the prognostic value of CD10, a metalloproteinase that can promote cancer aggressiveness through enzymatic degradation and intracellular signaling crosstalk, in malignant pleural mesothelioma.

METHODS

CD10 immunostaining was performed for 176 cases of malignant pleural mesothelioma (epithelioid, 148; biphasic, 14; sarcomatoid, 14), and its expression was dichotomized as negative (no staining) or positive (any staining). Epithelioid tumors were classified as pleomorphic subtype when cytologic pleomorphism was ≥10 % of the tumor. Overall survival (OS) was analyzed by log-rank tests and Cox proportional hazard models.

RESULTS

Tumoral CD10 expression was identified in 42 % of epithelioid non-pleomorphic tumors, 57 % of epithelioid pleomorphic tumors, 79 % of biphasic tumors, and 93 % of sarcomatoid tumors (p < 0.001). Positive CD10 expression was correlated with higher mitotic count (p = 0.002). Overall survival for patients with positive CD10 expression was significantly shorter than that for patients with negative CD10 expression in all patients (p = 0.001) and in patients with epithelioid tumor (p = 0.04). On multivariate analysis, CD10 expression was an independent prognostic factor for all patients (hazard ratio 1.48; p = 0.019).

CONCLUSIONS

Tumoral CD10 expression correlated with aggressive histologic types and higher mitotic activity and is an independent prognostic factor for patients with malignant pleural mesothelioma.

A diagnosis of malignant pleural mesothelioma can be made by effusion cytology: results of a 20 year audit

AIMS

Cytological diagnosis of malignant pleural mesothelioma (MPM) is controversial, but has been used in our institution for over 30 years. To assess the role of effusion cytology in mesothelioma diagnosis we conducted an audit of pleural fluid cytology results over a 20 year period (1988-2007).

METHODS

Pleural samples were received from 6285 patients; data linkage with Western Australian Cancer and Mesothelioma Registries demonstrated that 815 of these patients had a diagnosis of MPM. Cytological examination of a pleural effusion specimen had been performed in 517 (63%) of these 815 patients.

RESULTS

Definitive cytological diagnosis of MPM was made in 377/517 cases, resulting in an 'absolute' sensitivity of 73%. An additional 66 patients were diagnosed as atypical/suspicious, resulting in a 'complete' sensitivity of 86%. If only biopsy/necropsy proven cases are considered, the absolute sensitivity is 68% and the complete sensitivity is 82%. There were no false positive diagnoses of malignancy; two patients with metastatic adenocarcinoma were initially diagnosed as MPM, prior to the availability of specific mesothelial markers, resulting in a positive predictive value of 99%.

CONCLUSIONS

Effusion cytology is an inexpensive, minimally invasive procedure which should be included in the diagnostic work-up of cases of suspected MPM.

PAX8: a sensitive and specific marker to identify cancer cells of ovarian origin for patients prior to neoadjuvant chemotherapy

BACKGROUND

Neoadjuvant chemotherapy followed by cytoreduction surgery has been used where an accurate cytologic or pathologic diagnosis is usually required before the initiation of neoadjuvant chemotherapy. However, it is difficult to make definitive diagnosis of presence of cancer cells, particularly gynecologic versus non-gynecologic origin, from those ascites specimens due to the absence of specific biomarkers of gynecologic cancers. In the present study, we evaluated if, in addition to the routine morphologic diagnosis, the biomarker PAX8 could be useful in recognition of ovarian epithelial cancer cells prior to the neoadjuvant chemotherapy.

METHODS

Two hundred and two cytology specimens including 120 pretreatment ovarian cancer samples, 60 benign controls, and 22 malignant non-gynecologic cases were studied. All cytology slides were morphologically reviewed in a blinded fashion without knowing corresponding pathology diagnosis, if present. A total of 168 cytology specimens with a cell block were stained with PAX8 and Calretinin. These included patients with potential for ovarian cancer neoadjuvant chemotherapy (n=96), metastatic cancers (n=22), and benign controls (n=50).

RESULTS

Among the 96 ascitic samples prior to neoadjuvant chemotherapy, 76 (79%) showing morphologic features consistent with cancers of ovarian primary were all PAX+/Calretinin-. The remaining 20 (21%) cases were positive for adenocarcinoma, but morphologically unable to be further classified. Among the 22 metastatic cancers into the pelvis, one case with PAX8+/Calretinin- represented a renal cell carcinoma and the remaining 21 PAX8-/Calretinin- metastatic cancers were either breast metastasis (n=4) and the metastasis from gastrointestinal tract (n=17). Among the 50 benign control pelvic washing cases, 5 PAX8+/Calretinin-cases represented endosalpingiosis (n=4) and endometriosis (n=1), 25 PAX8-/Calretinin+cases showed reactive mesothelial cells, and the remaining 20 specimens with PAX8-/Calretinin- phenotype typically contained inflammatory or blood cells without noticeable diagnostic epithelia.

CONCLUSIONS

PAX8 identifies all Müllerian derived benign or malignant epithelia. When combining with Calretinin, PAX8 is a sensitive marker to diagnose the carcinomas of ovarian origin, which will be ideal to be used for those patients with a possible advanced ovarian cancer prior to receiving neoadjuvant chemotherapy.

Value of PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4 immunostaining in distinguishing pleural epithelioid mesothelioma from metastatic renal cell carcinoma

Both mesotheliomas and renal cell carcinomas can present a wide variety of cytomorphologic features and histologic patterns. Because of this, renal cell carcinomas metastatic to the pleura and lung can be confused with mesotheliomas. Recently, a variety of positive carcinoma markers, including kidney-associated markers, have become available. The aim of this study is to investigate the value of some of these markers, specifically PAX8, PAX2, napsin A, carbonic anhydrase IX, and claudin-4, for assisting in distinguishing pleural epithelioid mesotheliomas from metastatic renal cell carcinomas. To do so, a total of 40 pleural epithelioid mesotheliomas and 55 renal cell carcinomas (33 clear cell, 10 papillary, and 12 chromophobe) were investigated. In all, 91% of the renal cell carcinomas expressed claudin-4, 89% PAX8, 60% PAX2, 71% carbonic anhydrase IX, and 29% napsin A. All of the mesotheliomas were positive for carbonic anhydrase IX and were negative for all of the other markers. On the basis of these results, it is concluded that claudin-4 and PAX8 have a higher sensitivity and specificity for assisting in discriminating between pleural epithelioid mesotheliomas and renal cell carcinomas when compared with all of the other positive carcinoma markers that are, at present, recommended to be included in the immunohistochemical panels used in this differential diagnosis. Even though PAX2 and napsin A are highly specific, because of their low sensitivity, they have only a limited value. Carbonic anhydrase IX is not useful.

Functional significance of erythropoietin in renal cell carcinoma

One of the molecules regulated by the transcription factor, hypoxia inducible factor (HIF), is the hypoxia-responsive hematopoietic factor, erythropoietin (EPO). This may have relevance to the development of renal cell carcinoma (RCC), where mutations of the von Hippel-Lindau (VHL) gene are major risk factors for the development of familial and sporadic RCC. VHL mutations up-regulate and stabilize HIF, which in turn activates many downstream molecules, including EPO, that are known to promote angiogenesis, drug resistance, proliferation and progression of solid tumours. HIFs typically respond to hypoxic cellular environment. While the hypoxic microenvironment plays a critical role in the development and progression of tumours in general, it is of special significance in the case of RCC because of the link between VHL, HIF and EPO. EPO and its receptor, EPOR, are expressed in many cancers, including RCC. This limits the use of recombinant human EPO (rhEPO) to treat anaemia in cancer patients, because the rhEPO may be stimulatory to the cancer. EPO may also stimulate epithelial-mesenchymal transition (EMT) in RCC, and pathological EMT has a key role in cancer progression. In this mini review, we summarize the current knowledge of the role of EPO in RCC. The available data, either for or against the use of EPO in RCC patients, are equivocal and insufficient to draw a definitive conclusion.

Identification and functional characterization of pVHL-dependent cell surface proteins in renal cell carcinoma

The identification of cell surface accessible biomarkers enabling diagnosis, disease monitoring, and treatment of renal cell carcinoma (RCC) is as challenging as the biology and progression of RCC is unpredictable. A hallmark of most RCC is the loss-of-function of the von Hippel-Lindau (pVHL) protein by mutation of its gene (VHL). Using the cell surface capturing (CSC) technology, we screened and identified cell surface N-glycoproteins in pVHL-negative and positive 786-O cells. One hundred six cell surface N-glycoproteins were identified. Stable isotope labeling with amino acids in cell culture-based quantification of the CSC screen revealed 23 N-glycoproteins whose abundance seemed to change in a pVHL-dependent manner. Targeted validation experiments using transcriptional profiling of primary RCC samples revealed that nine glycoproteins, including CD10 and AXL, could be directly linked to pVHL-mediated transcriptional regulation. Subsequent human tumor tissue analysis of these cell surface candidate markers showed a correlation between epithelial AXL expression and aggressive tumor phenotype, indicating that pVHL-dependent regulation of glycoproteins may influence the biologic behavior of RCC. Functional characterization of the metalloprotease CD10 in cell invasion assays demonstrated a diminished penetrating behavior of pVHL-negative 786-O cells on treatment with the CD10-specific inhibitor thiorphan. Our proteomic surfaceome screening approach in combination with transcriptional profiling and functional validation suggests pVHL-dependent cell surface glycoproteins as potential diagnostic markers for therapeutic targeting and RCC patient monitoring.

Value of PAX2 immunostaining in tumor diagnosis: a review and update

PAX2 is a member of the PAX family of transcription factors that, together with PAX8, is involved in the regulation of the organogenesis of the kidney and the Müllerian system. Recent investigations have demonstrated that, among tumors, PAX2 is commonly expressed in epithelial tumors of the kidney and female genital tract. Although PAX2 expression has also been reported in B-cell lymphomas and rhabdomyosarcomas, especially alveolar rhabdomyosarcomas, it has been suggested that the positivity in these tumors was most probably due to a cross-reactivity of the anti-PAX2 antibody used in those investigations with other members of the PAX protein family. An analysis of published studies indicates that PAX2 sensitivity for epithelial renal neoplasms and epithelial tumors of the female genital tract is lower than that of PAX8. In contrast to the latter marker, however, PAX2 does not appear to be expressed in epithelial tumors of the thyroid gland or thymus. Because of its restricted expression, PAX2 has proved to be a useful immunohistochemical marker with a wide range of diagnostic applications in surgical pathology, some of which will be briefly reviewed.

Application of immunohistochemistry in the diagnosis of epithelioid mesothelioma: a review and update

A large number of immunohistochemical markers that can assist in the differential diagnosis of epithelioid mesotheliomas are currently available. Because these markers are expressed differently in the various types of carcinomas that can metastasize to the serosal membranes and can potentially be confused with epithelioid mesothelioma, their selection for inclusion in a diagnostic panel largely depends on the differential diagnosis, as well as on which ones work the best in a given laboratory. Traditionally, the panels used in the differential diagnosis of epithelioid mesothelioma have consisted of a combination of positive mesothelioma markers and broad-spectrum carcinoma markers. At present, a wide variety of organ-associated carcinoma markers such as thyroid transcription factor-1 and napsin A for the lung, PAX 8 and PAX 2 for the kidney, and Müllerian-derived tumors; gross cystic disease fluid protein-15 and mammaglobin for the breast; and CDX2 for intestinal differentiation are available, which can assist in establishing the site of origin of an adenocarcinoma when included in a diagnostic panel. This article provides updated information on the composition of the panels of markers recommended in the various differential diagnoses.

Diffuse Malignant Mesothelioma

Diffuse malignant mesothelioma (DMM) is an uncommon cancer with great clinical significance because it currently remains an incurable disease, and most patients die within months after diagnosis. Although DMM incidence is leveling off or decreasing in developed countries because of the strict control of asbestos use, it is increasing in countries without adequate asbestos control. In some settings, benign, reactive mesothelial hyperplasias and organizing pleuritis can be difficult to differentiate from DMM and vice versa, and the variety of DMM's histopathologic features generates an extensive list of differential diagnoses with other malignancies, particularly, metastatic malignancies, which are more frequent in the pleura than are primary malignancies. These two issues are the topic of discussion in this review, along with a brief presentation of a case of DMM that presented in a 66-year-old man with recurrent, right pleural effusions, and in whom, diagnosis of DMM had not been suspected clinically, radiographically, surgically, grossly, or initially, on frozen section. It was not until focal invasion into the skeletal muscle was discovered on permanent sections that a diagnosis of DMM could be established.

Role of immunohistochemistry in diagnosing renal neoplasms: when is it really useful?

CONTEXT

With the refinement of molecular and histologic classifications of renal neoplasms and the availability of more-effective molecular targeted therapy for specific renal neoplasms, immunohistochemical techniques will play an increasingly important role in the diagnosis of renal neoplasm. During the past few decades, many markers have been evaluated for their role in the diagnosis, prognosis, and prediction of treatment for renal neoplasms. The number of useful markers in our routine practice continues to increase. The challenge will be to choose among them and to decide in which situations immunohistochemistry will be truly useful.

OBJECTIVES

To review the diagnostic utility of molecular markers for renal neoplasms and common diagnostic scenarios that call for immunohistochemistry in routine practice.

DATA SOURCES

This review is based on published literature and personal experience.

CONCLUSIONS

Some of the most important and useful markers for the diagnosis of renal neoplasm include cytokeratins, vimentin, PAX2, PAX8, RCC marker, CD10, E-cadherin, kidney-specific cadherin, parvalbumin, claudin-7, claudin-8, α-methylacyl coenzyme A racemase, CD117, TFE3, thrombomodulin, uroplakin III, p63, CD57, and carbonic anhydrase IX. Each marker has its diagnostic role in a specific diagnostic setting. The common diagnostic situations that call for immunohistochemical staining are differential diagnoses of renal versus nonrenal neoplasms, histologic subtyping of renal cell carcinoma, diagnosis of rare primary renal neoplasms, diagnosis of renal neoplasms in small core-biopsy specimens, diagnosis of possible metastatic renal carcinomas, and less frequently, molecular prognostication.

Value of PAX 8 immunostaining in tumor diagnosis: a review and update

PAX 8 is a transcription factor involved in the regulation of organogenesis of the thyroid gland, kidney, and Müllerian system. Recent studies have shown that, among tumors, PAX 8 is commonly expressed in epithelial tumors of the thyroid and parathyroid glands, kidney, thymus, and female genital tract. Although PAX 8 expression has also been reported in certain neuroendocrine tumors, including well-differentiated pancreatic neuroendocrine tumors, and duodenal and rectal carcinoids, as well as in B-cell lymphomas, it has recently been shown that the PAX 8 positivity reported in these tumors was due to a cross-reactivity of the antibody used with the N-terminal region of PAX 6 and PAX 5, respectively. Owing to its restricted expression, PAX 8 has proved to be a useful immunohistochemical marker with a wide range of diagnostic applications in surgical pathology, some of which are briefly reviewed.

Epithelioid Lesions of the Serosa

Context.—Diagnosing epithelioid serosal lesions remains a challenge because numerous different processes—primary or secondary, benign or malignant—occur in body cavities, some of which are very rare.

Objectives.—To review the newest literature and to describe the morphologic criteria and immunohistochemical markers that are useful for distinguishing epithelioid serosal lesions.

Data Sources.—Previously published literature concentrating on the newest research findings. Earlier reviews are principally referred to for established diagnostic criteria.

Conclusions.—Immunohistochemistry with a panel of antibodies has made the diagnosis of epithelioid serosal lesions very reliable. When deciding on antibodies used in differential diagnosis, it is important to consider tumor location, clinical and radiologic information, and morphologic features. Immunohistochemistry is less useful in the differential diagnosis of benign versus malignant mesothelial lesions. The diagnosis of benign versus malignant mesothelial proliferations still relies on the histologic criteria of invasion.

Inhibin-α and synaptophysin immunoreactivity in synovial sarcoma with granular cell features

We recognized immunoreactivity for the α subset of inhibin and synaptophysin in synovial sarcomas with granular cell features. Histologic findings of 90 cases of synovial sarcoma were reviewed. Two (2.2%) of the 90 cases had granular cell features, showing sheet or nested proliferation of characteristic epithelioid cells with abundant eosinophilic and granular cytoplasm, in addition to the typical spindle cell component. The 2 cases were both female (aged 86 and 76 years). The tumors were located in the foot and the retroperitoneum and measured 3.5 and 14 cm in maximum diameter. Reverse transcriptase polymerase chain reaction analysis revealed SS18-SSX1 transcripts in both cases. SS18 gene rearrangement was detected in granular cells as well as spindle cells by chromogenic in situ hybridization. Immunohistochemistry found the granular cells to be positive for inhibin-α in both cases and for synaptophysin in 1 case, whereas spindle cells were not. Thirty-six cases (20 monophasic fibrous, 11 biphasic, and 5 poorly differentiated synovial sarcomas) were additionally examined for comparison; they showed no immunoreactivity for inhibin-α or synaptophysin. This is the first report of immunoreactivity for inhibin-α and synaptophysin in synovial sarcoma. These immunohistochemical findings might be characteristic of synovial sarcomas with granular cell features.

Pathohistological diagnosis and differential diagnosis

Malignant mesothelioma is a rare aggressive tumour arising from mesothelial cells of the pleural and peritoneal cavity including pericardium and tunica vaginalis testis. Malignant mesothelioma occurs predominantly in men (>90%). Asbestos exposure is the best known and evaluated risk factor with a long latency period between exposure and onset of malignant mesothelioma ranging from 15 to 60 years. Exposure to erionite leads to higher incidences of mesothelioma and play an important role in environmental exposure (Turkey). Other possible risk factors are radiation, recurrent pleuritis/peritonitis and simian virus 40 (SV 40).Malignant pleural mesothelioma is most common, whereas malignant peritoneal mesothelioma accounts only for 6-10%. Infrequent sites of origin are the pericardium and tunica vaginalis in 1-2%.Malignant mesothelioma shows either diffuse growth pattern or occurs as a localised tumour mass. Diffuse type represents an aggressive tumour with poor prognosis and is incurable in most cases.According to the WHO classification, three histological subtypes are distinguished: epithelioid, sarcomatoid and biphasic malignant mesothelioma.Rare variants are desmoplastic type, a subtype of sarcomatoid mesothelioma, undifferentiated type and deciduoid type. Epithelioid type is the most frequent one, but biphasic malignant mesothelioma occurs in 30%. Pure sarcomatoid or biphasic type is seen less frequently in malignant peritoneal mesothelioma than in its pleural counterpart.Well-differentiated papillary mesothelioma is a generally non-invasive mesothelioma with low malignant potential that arises mostly in females in the peritoneal cavity. Histological type is an important prognostic marker. Longest survival is seen in patients with epithelioid malignant mesothelioma. Sarcomatoid subtype has the worst prognosis.Malignant mesothelioma shows macroscopical and microscopical similarities to benign lesions and other malignancies. Therefore, reactive mesothelial proliferations on the one hand and secondary tumours resembling mesothelial cells as well as benign or rare mesothelial tumours on the other hand have to be distinguished. Additional immunohistochemistry is essential in histopathological assessment using a marker panel of antibodies.

Immunohistochemical diagnosis of renal neoplasms

CONTEXT

Histologic diagnosis of renal neoplasm is usually straightforward by routine light microscopy. However, immunomarkers may be essential in several contexts, including differentiating renal from nonrenal neoplasms, subtyping of renal cell carcinoma (RCC), and diagnosing rare types of renal neoplasms or metastatic RCC in small biopsy specimens.

OBJECTIVE

To provide a comprehensive review of the diagnostic utility of immunomarkers for renal neoplasms.

DESIGN

This review is based on published literature and personal experience.

CONCLUSIONS

The following markers may have diagnostic utility in various diagnostic contexts: cytokeratins, vimentin, α-methylacyl coenzyme A racemase, carbonic anhydrase IX, PAX2, PAX8, RCC marker, CD10, E-cadherin, kidney-specific cadherin, parvalbumin, claudin-7, claudin-8, S100A1, CD82, CD117, TFE3, thrombomodulin, uroplakin III, p63, and S100P. Cytokeratins are uniformly expressed by RCC, albeit in a somewhat limited amount in some subtypes, requiring broad-spectrum anti-CK antibodies, including both low- and high-molecular-weight cytokeratins. PAX2 and PAX8 are sensitive and relatively specific markers for renal neoplasm, regardless of subtype. CD10 and RCC marker are sensitive to renal cell neoplasms derived from proximal tubules, including clear cell and papillary RCCs. Kidney-specific cadherin, parvalbumin, claudin-7, and claudin-8 are sensitive markers for renal neoplasms from distal portions of the nephron, including chromophobe RCC and oncocytoma. CK7 and α-methylacyl coenzyme A racemase are sensitive markers for papillary RCC; TFE3 expression is essential in confirming the diagnosis of Xp11 translocation RCC. The potentially difficult differential diagnosis between chromophobe RCC and oncocytoma may be facilitated by S100A1 and CD82. Thrombomodulin, uroplakin III, p63, and S100P are useful markers for urothelial carcinoma. Together with high-molecular-weight cytokeratins, PAX2, and PAX8, they can help differentiate renal pelvic urothelial carcinoma from collecting duct RCC. A sensitive marker for sarcomatoid RCC is still not available. Immunomarkers are most often used for diagnosing metastatic RCC. Compared with primary RCC, expression of the above-mentioned markers is often less frequent and less diffuse in the metastatic setting. Recognizing the variable sensitivity and specificity of these markers, it is important to include at least CD10, RCC marker, PAX2, and PAX8 in the diagnostic panel.

Cytomorphologic consideration in malignant ascites with renal cell carcinoma: A report of two cases

Effusions, especially peritoneal, are seen in less than 2% of patients with renal cell carcinoma (RCC). Since the tumor cells in RCC are bland and nondescript, the involvement of serous effusions is difficult to diagnose. An accurate recognition of malignant effusion and differentiation from reactive mesothelial cells is imperative. A 55-year-old male presented with gradually progressive ascites. Cytospin preparations from ascitic fluid showed reactive mesothelial cells admixed with few smooth-contoured clusters of cells with moderate cytoplasm, vesicular nuclei with prominent nucleolus. He had undergone nephrectomy for papillary RCC two years earlier. Another 36-year-old man underwent left nephrectomy for suspected RCC. Intra-operative ascitic fluid was sent for cytologic examination and showed numerous reactive mesothelial cells along with few clusters of cells with scant to moderate amount of cytoplasm, vesicular nucleus and a small nucleolus. Considering the histomorphology of the primary renal tumor in both cases, a cytologic diagnosis of malignant peritoneal effusion, morphologically compatible with RCC was rendered. RCC, due to its bland cytologic features, is easily overlooked in effusions. In a known patient, the cytopathologist must be extra vigilant to pick up the few cell clusters present in the fluid preparations and differentiate them from reactive mesothelial cells. A close inspection of the cytologic features and comparison with the histopathology of the primary tumor helps in making an accurate diagnosis.

CD10 Is Expressed in Most Epithelioid Hemangioendotheliomas: A Potential Diagnostic Pitfall

Context.—Epithelioid hemangioendothelioma (EHE) is a vascular neoplasm that occasionally is difficult to distinguish from primary/metastatic carcinomas, particularly when EHEs express keratins. We recently encountered an EHE with strong CD10 positivity mimicking renal cell carcinoma.

Objective.—To examine sensitivity and specificity of CD10 in EHE.

Design.—Nine EHEs were stained with keratins, factor VIII, CD31, CD34, and CD10. Mimics of EHE were also retrieved and stained with CD10.

Results.—The EHE patients included 5 men and 4 women. Patients ranged in age from 24 to 74 years. Tumors were located in liver (3), skin (2), lung/pleura (2), and sternomastoid and mediastinum (1 each). Two had skin metastases. All EHEs were positive for vascular markers. A total of 7 of 9 primary tumors expressed cytoplasmic and intracytoplasmic luminal CD10. The 2 skin metastases were positive, whereas 2 primary skin EHEs were negative. Of the mimics, CD10 showed staining in 7 of 23 cases: 3 of 3 renal cell carcinomas, 1 of 7 other carcinomas, 2 of 3 epithelioid angiosarcomas, 1 of 3 melanomas, 0 of 3 mesotheliomas, and 0 of 4 epithelioid hemangiomas.

Conclusions.—CD10 has a sensitivity of 78% (confidence interval, 63.6%–92.4%) and specificity of 70% (confidence interval, 54%–85.9%) for EHE. There is a growing list of tumors that show expression of CD10. Pathologists should be aware of this diagnostic pitfall.

Problems in mesothelioma diagnosis

Many centres are now seeing increasing numbers of patients with malignant mesothelioma. This presents pathologists involved in making the diagnosis with a number of problems, which can be divided into those encountered in making the distinction between mesothelioma and benign changes and those experienced in separating mesotheliomas from other types of epithelial and connective tissue tumours. Immunohistochemistry plays a major role in helping to make the diagnosis, but it should be interpreted with due regard to the clinical setting and radiological features, and with a knowledge of the wide morphological variations seen in mesothelioma. This review identifies some of these problems and addresses the uses and limitations of immunohistochemistry in different situations. It includes a discussion of some of the less common variants of mesothelioma and other pleural-based tumours that enter into the differential diagnosis.

Immunohistochemistry of pulmonary and pleural neoplasia

CONTEXT

The use of immunohistochemical stains has several applications in the evaluation of pulmonary and pleural neoplasms. The number of available immunohistochemical stains is continually expanding and, although these stains are an important diagnostic adjunct, their use is not without limitations and pitfalls.

OBJECTIVE

To review and summarize the primary immunohistochemical applications with regard to the most common pulmonary and pleural neoplasms and discuss newly developed markers and common pitfalls.

DATA SOURCES

Pertinent peer-reviewed literature emphasizing immunohistochemical applications in common lung and pleural tumors, unusual and problematic staining patterns in frequently encountered subtypes/histologic variants, and recently developed immunohistochemical stains of potential promise.

CONCLUSIONS

Immunohistochemical stains provide the greatest aid in establishing the site of origin of adenocarcinomas encountered in the lung and in separating epithelioid mesothelioma from adenocarcinoma. Certain subtypes of pulmonary adenocarcinomas may exhibit unusual staining patterns that may be potentially problematic. Immunohistochemistry has a more limited role in separating small cell carcinoma from non-small cell carcinoma, and extreme caution must be used in the situation of crushed biopsy specimens.

Diagnostic importance of 9p21 homozygous deletion in malignant mesotheliomas

Definitive diagnosis of malignant mesothelioma in small specimens can be extremely difficult based on morphology alone. Homozygous deletion of 9p21, the locus harboring the p16 gene, has been reported as the most common genetic alteration in malignant mesotheliomas. Recent studies demonstrated that this alteration may be useful for differentiating benign from malignant mesothelial proliferations in cytology specimens. The aim of this study was to evaluate the diagnostic utility of homozygous deletion of 9p21 assessed by fluorescence in situ hybridization (FISH) in mesothelial proliferations involving serosal surfaces in paraffin-embedded tissue. p16 protein immunoexpression was also explored as a potential diagnostic aid. FISH analysis demonstrated homozygous deletion of the 9p21 locus in 35 of 52 cases (67%) of pleural mesothelioma and in 5 of 20 cases of peritoneal mesothelioma (25%) (P<0.005). None of 40 cases of reactive pleural mesothelial proliferations showed p16 deletion (P<0.005). Loss of immunoexpression of p16 was observed in 71% of the peritoneal mesotheliomas, 40% of the pleural malignant mesotheliomas and 15% of the reactive mesothelial cells. Homozygous deletion did not correlate with p16 protein expression in any of the studied groups. Our study suggests that 9p21 homozygous deletion assessed by FISH on paraffin-embedded tissue may be helpful for differentiating between malignant mesotheliomas and reactive mesothelial proliferations. A discrepancy between p16 protein expression and homozygous deletion suggests that other molecular mechanisms may play a role in p16 protein expression in mesothelial proliferations.

Application of immunohistochemistry to the diagnosis of malignant mesothelioma

CONTEXT

The diagnosis of malignant mesothelioma (MM) is rendered with the aid of immunohistochemistry to demonstrate the presence of "mesothelial," "epithelial," or "sarcomatous" differentiation. Antibody panels that have been proposed for the distinction between MM and other neoplasms usually include 2 or more epithelial markers used to exclude the diagnosis of a carcinoma, such as monoclonal and polyclonal carcinoembryonic antigen, Ber-EP4, B72.3, CD15, MOC-31, thyroid transcription factor 1, BG8, and others, and 2 or more mesothelial markers used to confirm the diagnosis of MM, such as cytokeratin 5/6, calretinin, HBME-1, thrombomodulin, WT-1, mesothelin, D2-40, and podoplanin. In general, most antibody panels provide excellent sensitivity and specificity for the differential diagnosis between MM epithelial variant and adenocarcinoma, particularly of lung origin. However, the accuracy of these markers is lower for the diagnosis of sarcomatous MM and for the differential diagnosis between MM and squamous cell carcinoma and carcinomas of renal, ovarian, and other origin.

OBJECTIVE

To identify optimal antibody panels for the diagnosis of MM.

DATA SOURCES

Literature review to determine how many and which mesothelial and epithelial markers need to be included in differential diagnosis antibody panels.

CONCLUSIONS

Various antibody panels have been recommended for the diagnosis of MM, with no overall consensus about how many and which markers should be used. A recent study with Bayesian statistics has demonstrated that the use of many markers does not provide higher diagnostic accuracy than the use of selected single antibodies or various combinations of only 2 markers. There is a need for the development of evidence-based or consensus-based guidelines for the diagnosis of MM in different differential diagnosis situations.

Application of immunohistochemistry to cytology

CONTEXT

The uses of monoclonal antibodies via immunochemistry have been reported frequently within the literature using various methodologies with applications to cytology specimens. The direct application of immunochemistry to cytology may have a variety of pitfalls that the general pathologist familiar with its application to histology may be unaware of when applying it prospectively to patient specimens.

OBJECTIVE

To review common pitfalls when applying immunochemistry to cytology specimens and to suggest approaches to the more common differential dilemmas that apply to a variety of cytology specimens that could be seen in a general pathology practice.

DATA SOURCES

The authors' own experiences of applying immunochemistry to cytopathology specimens within an academic setting along with supportive data from the literature.

CONCLUSIONS

Immunochemistry can be used to increase the predictability of a cytology diagnosis if care is taken with the cytology sample preparation methodology and there is judicious use of select monoclonal antibody panels to support a specific cytology diagnosis. Up-to-date evidence-based antibody databases should be used when selecting antibody panels.

Recombinant erythropoietin differently affects proliferation of mesothelioma cells but not sensitivity to cisplatin and pemetrexed

The combination of cisplatin and pemetrexed represents the newly established standard of care for patients with unresectable malignant mesothelioma (MM). However, this chemotherapy regimen appears to be associated with an increased prevalence of higher grade anemia as compared to treatment with cisplatin alone. Human recombinant erythropoietin (rHuEpo) is currently used for the treatment of anemia in cancer patients. Still, following the finding that the erythropoietin receptor (EpoR) is expressed by several tumor cells types and after the trials reporting that the recombinant cytokine can adversely affect tumor progression and patient survival, the clinical safety of rHuEpo administration to neoplastic patients has recently been questioned. The observation that the expression of EpoR, variably associated with the expression of the cognate ligand, is a common feature of MM cells prompted us to investigate whether treatment with rHuEpo could elicit proliferative and cytoprotective signals in EpoR-positive MM cell lines. Biochemical responsiveness of MM cells to rHuEpo was demonstrated by the time-course activation of both ERK1/2 and AKT following treatment with the recombinant cytokine. A moderately increased mitogenic activity was observed in two out of five MM cell lines treated with pharmacologically relevant concentrations of rHuEpo. On the other hand, the recombinant cytokine, administered either before or after cisplatin and pemetrexed, failed to interfere with the cytotoxic effects exerted by the chemotherapeutic drugs on the five MM cell lines. According to the presented findings, rHuEpo appears to have an overall limited impact on cell growth and no effect on MM sensitivity to chemotherapy.

Applications and limitations of immunohistochemistry in the diagnosis of malignant mesothelioma

Malignant mesothelioma is an uncommon malignant epithelial neoplasm originating from the serosal surface of body cavities. Because serosal surfaces are a common site of metastatic spread for a variety of malignant neoplasms originating from internal organs, separating malignant mesothelioma from metastatic tumors is of clinical importance. The diagnosis of malignant mesothelioma is complex and usually requires a multimodal approach that includes careful clinical history and physical examination, imaging studies, and tissue sampling for multimodal evaluation including routine histology, histochemistry, electron microscopy, and immunohistochemical tests. Of these, immunohistochemistry has emerged as the most valuable and readily available modality for the routine evaluation of these tumors. Unfortunately, no specific antibodies have yet been developed that can be accepted as exclusive for these tumors. The immunohistochemical diagnosis of malignant mesothelioma therefore depends on the use of a panel of stains that includes markers that are commonly expected to react with these tumors ("positive" markers) and markers that are not commonly expected to react with these tumors ("negative" markers). Additionally, the selection and utility of these various markers can vary considerably based on a constellation of circumstances, including patient sex, histologic appearance of the tumor (ie, epithelioid vs. sarcomatoid, etc), and various other clinical circumstances. Herein, we will review the currently available immunohistochemical markers used for the diagnosis of malignant mesothelioma and offer suggestions for the use of appropriate panels of stains based on specific morphologic types and clinical circumstances.