Perianal basal cell carcinoma is a very rare tumor accounting for only 0.2% of the anorectal tumors. It must be distinguished from basaloid carcinoma of the anus, which resembles it histologically but shows a much more aggressive behavior, metastasizes early, and often proves fatal, thus requiring different therapy. Differential diagnosis of both entities by light microscopy may be difficult. Five cases of perianal basal cell carcinoma and five cases of basaloid carcinoma were studied by means of immunohistochemistry and flow cytometry. Some immunohistochemical markers, such as epithelial membrane antigen, carcinoembrionic antigen, and keratins, as well as the lectin Ulex europaeus agglutinin I stained basaloid carcinoma and were negative for basal cell carcinoma. In contrast, the monoclonal antibody Ber-EP4 seems to be a good marker for perianal basal cell carcinoma and useful in differentiating it from basaloid carcinoma of the anus. Basaloid carcinomas are associated with a significantly higher S-phase fraction than are perianal basal cell carcinomas (p < 0.01).

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Clear cell carcinoma (CCC) is a rare low-grade carcinoma that represents only 1% to 2% of all salivary glands tumors. The finding of a clear cell tumor in a parotid gland involves the necessity of differential diagnosis between primary clear cell parotid tumors and metastases, mainly from kidney. The biological behavior is not very aggressive and development, which is very slow, is usually asymptomatic and indeed, the tumor often reaches considerable dimensions before being diagnosed. The treatment of choice is the surgical excision. There are rare cases of local recurrence and distant metastases. The aim of this article is to report a primary CCC in the parotid gland that microscopically closely resembled a metastatic CCC of renal origin, making microscopic differentiation difficult.

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