SOX10 immunohistochemistry in sweat ductal/glandular neoplasms.

BACKGROUND: SOX10 is a newer Schwannian and melanocytic marker that has generated great interest for its relative sensitivity and specificity in the diagnosis of neural crest-derived tumors. Previous studies with SOX10 have shown positive immunohistochemical expression in cutaneous eccrine glands and negative expression in eccrine ducts, apocrine glands and hair follicles. Thus, we hypothesized that some sweat gland tumors of presumed eccrine origin would be positive for SOX10, whereas apocrine-derived sweat gland tumors would not. METHODS: A mouse monoclonal anti-SOX10 (clone BC34: Biocare Medical; Concord, California) immunohistochemical antibody was performed on various sweat gland tumors and basal cell carcinoma. RESULTS: SOX10 showed positivity in spiradenomas (13/13), cylindromas (9/10), hidradenoma papilliferum (10/10), syringocystadenoma papilliferum (8/10), apocrine adenomas (8/10), and negativity in poromas (0/12), syringomas (0/10), and basal cell carcinomas (0/13). There was mixed staining of hidradenomas (6/15). CONCLUSIONS: SOX10 immunohistochemistry may be of utility in distinguishing some of the varying adnexal tumors from each other, and from basal cell carcinoma (BCC), but given the staining of both apocrine and eccrine tumors, does not seem to provide information as to their origins as either eccrine or apocrine tumors.

mASH1 is Highly Specific for Neuroendocrine Carcinomas: An Immunohistochemical Evaluation on Normal and Various Neoplastic Tissues.

CONTEXT: -High-grade neuroendocrine carcinomas and carcinoids can arise in different sites such as lung, gastrointestinal tract, prostate, and skin. Classic neuroendocrine markers such as CD56, synaptophysin, and chromogranin cannot distinguish carcinoids from high-grade neuroendocrine carcinomas. Recently, mouse monoclonal mASH1 has been shown to help discriminate carcinoids from high-grade neuroendocrine carcinomas in various neoplastic sites. To date, there have been no comprehensive immunohistochemistry studies with mASH1 on nonneuroendocrine neoplasms. OBJECTIVE: -To evaluate the specificity and sensitivity of mASH1 in various normal and neoplastic tissues, including lung cancers. DESIGN: -Formalin-fixed, paraffin-embedded tissue microarrays consisting of normal tissues and various neoplastic tissues were immunohistochemically evaluated with mASH1. RESULTS: -In normal tissues (n = 30), mASH1 (nuclear staining) was sparsely expressed in the molecular cell layer, white matter, and granular cell layer of cerebellum; C cells in thyroid; and epithelial cells in thymus. In lung cancers, mASH1 stained 1.1% (1 of 93) of adenocarcinomas, 0.9% (1 of 111) of squamous cell carcinomas, 0% (0 of 30) of large cell carcinomas, 66.7% (6 of 9) of large cell neuroendocrine carcinomas, and 82.5% (94 of 114) of small cell carcinomas. In various other neoplastic tissues (n = 1114), mASH1 was expressed in thyroid medullary carcinomas, thymic carcinomas, and brain cancers; mASH1 was also expressed in a very low percentage of breast carcinomas, ovarian cancers, and pancreatic neuroendocrine tumors. All typical carcinoids of various sites were negative (0 of 11), however, in lung atypical carcinoids, mASH1 was expressed in 42.9% (9 of 21). CONCLUSIONS: -Although not organ specific, mASH1 is highly specific for high-grade neuroendocrine carcinomas versus carcinoids and other nonneuroendocrine neoplasms.

CDH17 Is a More Sensitive Marker for Gastric Adenocarcinoma Than CK20 and CDX2.

CONTEXT: -CDH17, which is expressed in the intestinal epithelium, is a novel oncogene involved in tumor invasion and metastasis. A panel consisting of cytokeratin (CK) 7, CD20, and CDX2 antibodies is typically used to diagnose gastrointestinal adenocarcinomas. However, studies have shown that CDH17 is a highly specific marker for gastrointestinal adenocarcinoma and may be important in clinical diagnosis. OBJECTIVE: -To evaluate the sensitivity and specificity of CDH17, CK20, and CDX2 antibodies in neoplastic tissues, with emphasis on colon, stomach, and esophageal gastrointestinal lineage. DESIGN: -Immunohistochemistry was performed with CDH17, CK20, and CDX2 antibodies on formalin-fixed, paraffin-embedded tissue microarrays from normal (n = 26) and neoplastic (n = 884) tissues. RESULTS: -CDH17 immunostaining was positive in 97.3% (145 of 149) of colon adenocarcinomas, whereas CK20 and CDX2 stained positively in 88.6% (132 of 149) and 93.3% (139 of 149), respectively. In metastatic colon cancers, CDH17, CK20, and CDX2 positive staining was observed in 90.6% (29 of 32), 59.4% (19 of 32), and 81.3% (26 of 32) of cases, respectively. In stomach adenocarcinomas, CDH17 positively stained 64.0% (112 of 175) of tissues, compared to CK20 and CDX2, where staining was observed in only 24.6% (43 of 175) and 46.9% (82 of 175), respectively. In esophageal adenocarcinomas, CDH17, CK20, and CDX2 stained 38.7% (12 of 31), 25.8% (8 of 31), and 29% (9 of 31) of specimens, respectively. Low or no expression was observed in other neoplastic tissues, except pancreatic cancers, where CDH17 displayed higher expression than CK20 and CDX2. CONCLUSIONS: -CDH17 is a specific and more sensitive marker in the gastrointestinal tract than CK20 and CDX2. CDH17 may be especially valuable when gastrointestinal tumors are suspected in cancers of unknown primary.