The Distinction of Clear Cell Carcinoma of the Female Genital Tract, Clear Cell Renal Cell Carcinoma, and Translocation-Associated Renal Cell Carcinoma: An Immunohistochemical Study Using Tissue Microarray

Revisiting the use of CK7 and CK20 immunohistochemical stains in pathological diagnoses

BACKGROUND

Cytokeratin-7 (keratin-7; CK7) and cytokeratin-20 (keratin-20; CK20) have been among the most widely used markers in pathology for prediction of tumor site of origin or classification. However, with the increased availability of newer and more specific biomarkers and molecular techniques, it is timely to revisit the utility of CK7 and CK20 stains under different clinical settings.

METHODS

In the current study, we retrospectively reviewed 612 surgical pathology cases at our institution where CK7 and/or CK20 stains were performed and determined to what degree they contributed to the final diagnosis.

RESULTS

In CK7-and-CK20 cases, the stains had a major contribution in 5% of the cases. In CK7-only or CK20-only cases, the percentages of major contribution were 34% and 69% respectively. However, when only cases where CK7/CK20 stains were used to determine tumor site of origin, the contributions become more comparable across all three case types, where CK7/CK20 stains had major contribution in < 10% of cases. Notably, 11% of CK7-and-CK20 cases had no specific or suggestive diagnosis, and 40% of CK7-and-CK20 cases had staining patterns inconsistent with the final diagnosis. Detailed analysis demonstrates that CK7 and CK20 stains, used singly, are most useful in the diagnosis of a limited number of pathologic entities with distinct CK7 or CK20 expression patterns.

CONCLUSIONS

Our results suggest that the coordinate expression of CK7 and CK20 is generally not helpful in arriving at the final diagnosis. Reducing unnecessary immunohistochemical stains will help mitigate the rising healthcare cost and preserve tissue for molecular testing.

Clear Cell Carcinomas of Müllerian Type and Rete Testis Origin Presenting as Scrotal Masses: A Study of Seven Cases

Ovarian-type epithelial tumors involving the testis and paratestis are rare, with clear cell carcinomas (CCC) one of the least frequent. We report our experience with 4 müllerian-type (MT) CCCs presenting as testicular/scrotal masses and arising in the paratestis (n=2) and seminal vesicle (n=2; well supported in 1 case and likely in the other). In addition, we document 3 cases of papillary CCC exclusively within the rete testis (RTCCC) and seminiferous tubules and differing from the MT tumors. The patients with MTCCC were 24 to 85 years old (median, 42 y), and 2 had metastases at presentation. The 2 originating in the paratestis were associated with other MT tumors, an endometrioid borderline tumor and a papillary serous borderline tumor. The other 2 MTCCCs likely involved the testis via extension from seminal vesicle primaries through the vasa deferentia. All MTCCCs showed typical features, including tubules, simple papillae with hyalinized cores, and solid nests of polygonal clear cells with occasional hobnail features. Both paratesticular primaries showed sarcomatoid foci with tumor-associated neutrophilic infiltrates. The 3 RTCCCs presented in 54-, 57-, and 60-year-old men as testicular masses; they showed intrarete arborizing papillary growth with nonhyalinized fibrous cores and piled-up, solid foci, lacked hobnail cells, and expressed carbonic anhydrase IX (2/2) and CD10 (2/2) but not CA125, unlike the MTCCCs. On follow-up, 2 patients with MTCCC died of metastatic tumor (4 and 13.5 mo), a third developed ileal and retroperitoneal metastases at 13 months; and the fourth died at 13.5 months of unspecified cause. Follow-up of 2 patients with RTCCCs showed 1 disease free at 8 months and another alive with unknown disease status at 13 years. We conclude that CCCs involving the testis may either be of MT with often aggressive courses or show some features of renal tumors, with confinement to the rete testis and indolent behavior.

Primary Retroperitoneal Carcinomas: New Insights into Pathogenesis and Clinical Management in Comparison with Ovarian Carcinomas and Carcinoma of Unknown Primary

Primary retroperitoneal carcinomas are very rare tumors. Their pathogenesis remains unknown but may be associated with that of ovarian carcinomas, considering the similarity in morphology and gender preference. Although metaplasia of coelomic epithelium is the most widely accepted theory, the pathogenesis of retroperitoneal carcinomas may differ by histologic subtype, like ovarian carcinomas. Mucinous carcinoma, which develops in both women and men, may originate in both primordial germ cells and Walthard cell nests that may be derived from the fallopian tube. Serous carcinomas may be associated with endosalpingiosis, the presence of fallopian tube-like epithelium outside the fallopian tube, and a remnant Müllerian tract. Endometrioid and clear cell carcinomas appear to be associated with extraovarian endometriosis. Additionally, both carcinomas in the retroperitoneal lymph nodes may be metastatic diseases from endometrial and/or renal cell cancer that regress spontaneously (carcinoma of unknown primary). Retroperitoneal carcinomas are difficult to diagnose, as they have no characteristic symptoms and signs. Surgery is the cornerstone of treatment, but the necessity of chemotherapy may depend on histological subtype. Further studies are necessary, in particular studies on endosalpingiosis, as endosalpingiosis is a poorly understood condition, although it is associated with the development of both serous and mucinous carcinomas.

Evaluating Established Roles, Future Perspectives and Methodological Heterogeneity for Wilms’ Tumor 1 (WT1) Antigen Detection in Adult Renal Cell Carcinoma, Using a Novel N-Terminus Targeted Antibody (Clone WT49)

Renal cell carcinoma (RCC) is arguably the deadliest form of genitourinary malignancy and is nowadays viewed as a heterogeneous series of cancers, with the same origin but fundamentally different metabolisms and clinical behaviors. Immunohistochemistry (IHC) is increasingly necessary for RCC subtyping and definitive diagnosis. WT1 is a complex gene involved in carcinogenesis. To address reporting heterogeneity and WT1 IHC standardization, we used a recent N-terminus targeted monoclonal antibody (clone WT49) to evaluate WT1 protein expression in 56 adult RCC (aRCC) cases. This is the largest WT1 IHC investigation focusing exclusively on aRCCs and the first report on clone WT49 staining in aRCCs. We found seven (12.5%) positive cases, all clear cell RCCs, showing exclusively nuclear staining for WT1. We did not disregard cytoplasmic staining in any of the negative cases. Extratumoral fibroblasts, connecting tubules and intratumoral endothelial cells showed the same exclusively nuclear WT1 staining pattern. We reviewed WT1 expression patterns in aRCCs and the possible explanatory underlying metabolomics. For now, WT1 protein expression in aRCCs is insufficiently investigated, with significant discrepancies in the little data reported. Emerging WT1-targeted RCC immunotherapy will require adequate case selection and sustained efforts to standardize the quantification of tumor-associated antigens for aRCC and its many subtypes.

Expression and diagnostic implications of carbonic anhydrase IX in several tumours with predominantly clear cell morphology

AIMS

High expression of carbonic anhydrase IX (CA IX) has been reported in clear cell renal cell carcinoma (ccRCC); few studies have reported CA IX expression in other tumours with predominantly clear cell morphology. The aim of study was to examine the expression and diagnostic implications of CA IX in these latter tumours.

METHODS AND RESULTS

An immunohistochemical study was performed of 159 tumours with predominantly clear cell morphology. The results showed that, in addition to primary (25/25) and metastatic (10/11) ccRCC, CA IX was also expressed in breast (2/2), pulmonary (3/5) and hepatic (1/4) clear cell carcinoma, urothelial carcinoma with clear cell change (3/6), clear cell meningioma (4/6) and ependymoma (2/3), haemangioblastoma (10/10), and clear cell hidradenoma (5/6). However, while strong and diffuse positivity for CA IX was observed in ccRCC, clear cell breast carcinoma, haemangioblastoma, and clear cell hidradenoma, the other cases showed predominantly focal positivity for CA IX. In particular, CA IX staining was often seen at the periphery of necrotic areas.

CONCLUSIONS

Our results indicate that strong and diffuse CA IX expression may be useful for differentiating ccRCC from several clear cell tumours, with the exception of clear cell breast carcinoma, haemangioblastoma, and clear cell hidradenoma.

Primary clear cell adenocarcinoma of the colon presenting as a huge extracolic mass: A case report

A primary clear cell adenocarcinoma of the colon is a rare oncologic entity. The current study presents a case of such a tumor in the transverse colon of a 26-year-old male, and describes the computed tomography features of the neoplasm. The tumor appeared as an extensive extracolic mass, which displaced the loop of the small bowel and pancreas, and invaded the spleen. A laparotomy was performed and a huge mass measuring 12 cm maximally was revealed, arising from the transverse colon close to the left colonic flexure, with invasion of the spleen. The tumor and the spleen were resected concurrently. Histopathological examination of the excised mass revealed features of clear cell adenocarcinoma. A primary clear cell adenocarcinoma of the colon is a rare tumor, with only 13 cases reported in the English literature at present. The present case is reported here due to its rarity.