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Abstract

Primary cutaneous cribriform apocrine carcinoma is a rare adnexal neoplasm, usually presenting as a solitary nodule on the extremities of middle-aged adults. It has an indolent behavior; following complete wide excision, there are no reported cases of metastatic or recurrent disease. We report a case of a 55-year-old male with a lesion on the left lower leg. The biopsy showed an infiltrating, significantly atypical, glandular and ductal neoplasm within the mid and deeper dermis, arranged in cords and nests within fibrotic and mucinous stroma. The cells had round to oval nuclei with conspicuous basophilic nucleoli and clear chromatin. However apocrine differentiation was also present. Cribriform features as revealed by a distinct sieve-like arrangement of the neoplastic glandular elements within the foci of nested/micronodular growth were observed. No vascular, lymphatic, or perineural invasion was identified. The tumor was incompletely excised. The mucicarmine and PAS highlighted mucin and luminal secretions. The cells were positive for pancytokeratin, CK5/6, CK7, and CK19 confirming the epithelial ontogeny. p63 was predominantly negative, and Ki-67 showed a low proliferation index. Additional stains to rule out metastatic adenocarcinoma (CK20, PSA, CEA, CDX2, PAX8, TTF-1, synaptophysin, PR, ER) were negative. A diagnosis was rendered of primary cutaneous cribriform adenocarcinoma, likely of apocrine derivation, whereby the immunohistochemical profile militated against the diagnosis of metastatic adenocarcinoma. The lack of staining for p63 is a common finding in apocrine tumors including this rare variant.