Aaron C. Han

P-cadherin expression in breast carcinoma indicates poor survival.

The cadherin family of cell‐cell adhesion molecules and their associated proteins, the catenins, are essential to embryonic development and the maintenance of adult tissues. During development, the homotypic interaction of a particular cadherin with an identical cadherin expressed on a neighboring cell results in the sorting of cells to form distinctive tissues. Cadherins are believed to be tumor suppressors, and their altered expression and function have been associated with tumor development.

Expression of E-cadherin and N-cadherin in surface epithelial-stromal tumors of the ovary distinguishes mucinous from serous and endometrioid tumors

This study examines the expression of E-cadherin and N-cadherin in the most common epithelial tumors of the ovary. The homotypic interactions of distinctive members of the cadherin family of cell-cell adhesion molecules segregate cells into tissues during embryonic development, and their expression in tumors can be used to trace the histogenesis of tumor cells. Because the surface epithelium of the ovary is a modified mesothelium, we speculated that the expression of E (epithelial)-cadherin and N (neural, mesodermal)-cadherin may provide clues about the controversial origin of common epithelial ovarian tumors. Immunohistochemistry was performed in paraffin sections using well-characterized monoclonal antibodies to E- and N-cadherin and heat-induced antigen-retrieval methods. We found that serous and endometrioid tumors express both E- and N-cadherin. In contrast, mucinous tumors strongly express E-cadherin, but no N-cadherin. The presence of N-cadherin in serous and endometrioid tumors traces their origin to the mesoderm-derived ovarian surface epithelium. The absence of N-cadherin in mucinous tumors clearly distinguishes them from the former, suggesting histogenesis from a cell lineage other than the ovarian surface epithelium or aberrant differentiation mechanisms associated with neoplastic transformation.

Distinct cadherin profiles in special variant carcinomas and other tumors of the breast

The cadherins are homotypic adhesion proteins that are important in cell sorting during organogenesis. Classical cadherins include several different types that show tissue-specific expression. Cell lineage-specific expression of different cadherin subtypes can differentiate morphologically similar but histogenetically distinct tumors. We examined by immunohistochemistry in paraffin sections, the expression of E (epithelial), N- (neural), and P- (placental) cadherin in 36 unusual tumors of the breast (22 medullary carcinomas, 5 metaplastic carcinomas, 2 carcinosarcomas, 4 phyllodes tumors, and 3 periductal stromal tumors). All carcinomas stain with E-cadherin (22 of 22 medullary and 5 of 5 metaplastic). E-cadherin also stained the epithelial component but not the sarcomatous areas of 2 of 2 cases of carcinosarcomas. E-cadherin was not detected in the stromal tumors (phyllodes, periductal stromal tumor). N-cadherin was most frequently expressed in sarcomatoid metaplastic carcinomas (5 of 5), and variably in other tumors, including the sarcomatous area of carcinosarcoma (1 of 2), and 6 of 22 medullary carcinomas. P-cadherin was frequently identified in medullary carcinomas (20 of 22), in 5 of 5 metaplastic carcinomas, and in the proliferating stroma and benign epithelium of 3 of 3 periductal stromal, but not in phyllodes tumors (0 of 4). All sarcomatoid metaplastic carcinomas co-expressed all 3 classical cadherins. Our results show that these breast tumors have unique patterns of cadherin expression suggesting different histogenetic origin or lines of differentiation. The cadherin profiles in these tumors may be useful for classification and diagnosis.

Nuclear Localization of E-Cadherin Expression in Merkel Cell Carcinoma

CONTEXT Cadherins are cell-cell adhesion proteins that act as tumor suppressor genes and have a critical role in cell sorting and tissue formation during organogenesis. The pattern of cadherin expression constitutes a useful diagnostic and prognostic tool in the evaluation of tumors and for determining the histogenesis of tumor cells. We have previously characterized the cell types of several tumors based on the expression of individual cadherins. OBJECTIVE To investigate the expression of cadherins in Merkel cell carcinomas. DESIGN Paraffin immunohistochemical analysis of the 3 best-studied cadherins was performed on 35 cases of Merkel cell carcinoma. RESULTS E-cadherin was expressed in 34 (97%) of 35 Merkel cell carcinomas examined, N-cadherin was expressed in 22 (63%) of 35 cases, and P-cadherin was expressed in 15 (43%) of 35 cases. This frequency of cadherin expression was similar to a group of small cell and neuroendocrine tumors from other primary sites. Interestingly, the localization of E-cadherin expression was unique in Merkel cell carcinomas compared with other primary neuroendocrine tumors. Merkel cell carcinomas showed marked preference for nuclear versus membrane localization, whereas small cell tumors from other sites showed fewer cases of nuclear E-cadherin expression. The nuclear localization of E-cadherin did not correlate with cadherin-associated protein beta-catenin nuclear expression. CONCLUSIONS Our findings show that E-cadherin is the most frequently expressed cadherin in Merkel cell carcinoma, followed in frequency by N-cadherin then P-cadherin. The pattern of nuclear E-cadherin expression is more frequent for Merkel cell carcinoma than small cell tumors of other primary sites. These observations suggest that E-cadherin expression and function are altered in Merkel cell carcinoma, and this finding has potential use in the differential diagnosis of these tumors.

Cadherin expression in glandular tumors of the cervix.

The cadherins are homotypic adhesion proteins that are important in cell sorting during organogenesis. Classic cadherins include several different types that show tissue specific expression. Specific tissue expression of cadherins often is preserved in neoplastic transformation, and cadherin phenotype can be used to differentiate morphologically similar but histogenetically distinct tumors.

N‐cadherin distinguishes pleural mesotheliomas from lung adenocarcinomas

Cadherins are a family of cell–cell adhesion proteins. The homotypic binding of cadherins is critical for cell sorting and tissue formation during organogenesis. Different cadherin subtypes show lineage specific tissue expression, which has been exploited to differentiate histologically similar tumors of varying ontogeny. By applying immunohistochemistry to tissue sections, the authors have previously documented the utility of N‐cadherin in distinguishing between pleural mesotheliomas and lung adenocarcinomas, based on the observation that N‐cadherin is expressed in the former disease but not in the latter. Because the diagnosis of these diseases is frequently rendered on cytologic material rather than tissue biopsies, the authors wanted to assess the utility of N‐cadherin immunocytochemistry in evaluating material prepared with ThinPrep®.

Coexpression of cytokeratins 7 and 20 confirms urothelial carcinoma presenting as an intrarenal tumor

The differentiation of epithelial tumors arising in the kidney (urothelial vs. renal cell carcinoma) sometimes can be difficult by clinical and radiologic studies. Because urothelial and renal epithelium express unique cytokeratin (CK) 7 and 20 profiles, the authors studied the utility of these markers to confirm the diagnosis of urothelial carcinomas that present clinically as kidney masses.

Primary small cell carcinoma of the vagina.

BACKGROUND Primary vaginal small cell carcinoma is extremely rare, with a total number reported in English-language journals to date of 23. Most patients die of the disease within 2 years of diagnosis from metastatic disease. CASE A 69-year-old woman presented with vaginal spotting while on Premarin. She was subsequently diagnosed with Stage I (T1N0M0) small cell carcinoma of the vagina. She underwent concurrent chemoradiation and then brachytherapy for persistent disease. Due to residual disease after the brachytherapy, surgical resection was planned but aborted because of metastatic disease. CONCLUSIONS Of the three reported cases treated with concurrent chemoradiation, ours is the first case reported with persistent local disease after therapy. Extrapolating from the available clinical trials from lung carcinoma, concurrent chemoradiation as a primary treatment approach should still be considered.

p16 Expression in Squamous Lesions of the Female Genital Tract

The aim of this study was to examine the role of p16 in the pathogenesis of squamous carcinoma of the gynecologic tract. Squamous carcinoma and carcinoma in situ from the female genital tract were examined for the expression of p16 by paraffin immunohistochemistry. About 74% (40/54) of cases showed p16 expression. By primary site, 77% (23/30) of cervical, 67% (6/9) of vaginal and 85% (11/13) of vulvar primaries expressed p16, but two endometrial primary squamous carcinomas were negative (0/2). In addition, p16 was not identified in non-dysplastic tissue and low grade dysplasia. In cases where there were matched vaginal or vulvar and cervical primaries in a given patient, there was concordant positive p16 expression. It is concluded that p16 is frequently expressed in squamous carcinoma of the cervix, vagina and vulva, but not seen in cases of benign and low grade lesions. It may be a marker of transformation from a low to a high grade lesion. More cases of endometrial primaries need to be studied to see if these evolve by a p16-independent pathway.

Immunohistochemical confirmation of pulmonary papillary adenocarcinoma metastatic to ovaries

Metastatic papillary adenocarcinomas of the ovary are rare compared to primary ovarian papillary serous carcinomas. We report a case of pulmonary papillary adenocarcinoma metastatic to the ovary and show how this tumor can be differentiated immunohistochemically from an ovarian primary. Paraffin blocks of the ovarian tumor were analyzed for carcinoembryonic antigen, CA 125, surfactant, E-cadherin, N-cadherin, and vimentin. These markers are useful in differentiating epithelial tumors of lung versus ovarian origin. The papillary tumor showed expression of carcinoembryonic antigen, surfactant, and E-cadherin, but was negative for CA 125, N-cadherin, and vimentin. These findings support a lung carcinoma metastatic to the ovary.