This is the first reported case of an AFX with HMB-45 and MART-1 reactivity.

We describe a case of primary neuroendocrine carcinoma arising from the anterior vaginal wall of a 67-year-old woman. Primary neuroendocrine carcinoma of the vagina is a rare entity with only 25 previously reported cases in the literature. In previous reports, these tumors have not been distinguished from primary neuroendocrine carcinoma of the skin (Merkel cell carcinoma). The tumor was composed of cells that showed neuroendocrine-type nuclear features with hyperchromasia, nuclear molding, occasional small nucleoli, and a chromatin pattern that was finely granular. The tumor cells were positive for cytokeratin 20 (CK20), neuron specific enolase, pancytokeratin, epithelial membrane antigen, and chromogranin A expression. Ki-67, a marker of proliferation, was also positive in>90% of cells. The tumor cells showed intense expression of Bcl-2 oncoprotein and mild to moderate expression of c-KIT. Synaptophysin, neurofilament, CD45, CD56, CD10, S-100, HMB-45, cytokeratin 7, and thyroid transcription factor 1 were negative. This pattern of staining is consistent with a Merkel cell carcinoma. This is the first report of a primary neuroendocrine carcinoma of the vagina with a Merkel cell phenotype. Previous studies have not distinguished primary neuroendocrine carcinoma of the vagina from Merkel cell carcinoma of the skin. Positive expression of CK20 in primary small cell carcinoma of the vagina might represent a Merkel cell carcinoma subtype of this tumor.

Indeterminate fibrohistiocytic lesions of the skin share histological and immunohistochemical features of both benign fibrous histiocytoma/dermatofibroma and dermatofibrosarcoma protuberans (DFSP). Unlike dermatofibroma, DFSP harbors recurrent genetic aberrations resulting in the fusion of COL1A1 on chromosome 17 and PDGFB on chromosome 22. Because indeterminate fibrohistiocytic lesions share some features with DFSP, they were evaluated for the possible presence of COL1A1-PDGFB chimeric transcripts. Twelve formalin-fixed paraffin-embedded cases were examined for COL1A1-PDGFB chimeric transcripts using a previously validated sensitive multiplex reverse transcriptase-polymerase chain reaction assay. The median patient age was 52.5 years (33-70 years) with 9 females and 3 males. The most common site was the extremities (n = 8) followed by the trunk (n = 2) and the head and neck region (n = 2). All demonstrated the expected reactivity for both CD34 and factor XIIIa, and the majority focally infiltrated into subcutaneous fat. Of the 6 patients with follow-up, 2 had residual tumor excised, but no patient developed a recurrence. None of the tumors harbored COL1A1-PDGFB fusion transcripts identified by reverse transcriptase-polymerase chain reaction. Although indeterminate fibrohistiocytic lesions share some features with DFSP, the lack of COL1A1-PDGFB chimeric transcripts suggests that they are distinct entities.

No abstract

Context.—Skin cancers are the most common malignancies in this country. Treatment of these tumors often involves assessment of margins, which may be performed by frozen section. Objective.—This article discusses indications for frozen section, various approaches to gross examination of specimens, Mohs micrographic surgery, diagnostic pitfalls, methods to improve diagnostic accuracy, and special techniques. Data Sources.—The authors' extensive experience and review of the published literature. Conclusions.—Frozen sections play a vital role in the evaluation of margins of basal cell carcinomas and squamous cell carcinomas. The role of frozen sections in evaluation of soft tissue tumors is controversial. With rare exception, they have no role in the evaluation of melanocytic tumors.