Syringocystadenocarcinoma papilliferum: Case report and immunohistochemical comparison with its benign counterpart

Syringocystadenocarcinoma papilliferum (SCACP) is the malignant counterpart of syringocystadenoma papilliferum (SCAP), although only a few cases have been reported in the literature and its clinical and histologic characteris tics are not well known. We report a case of SCACP that started as an enlar ging nodule over 10 years in the perianal area of a 61-year-old man. Macros copically, the lesion was a black exophytic tumor, 6 cm in diameter, with a granular surface. Histologically, it was an in situ adenocarcinoma, showin g cytologic atypia and pagetoid spread in the surrounding epithelia, althou gh the clinicopathologic features were distinct from extramammary Paget's d isease. The tumor lacked the typical double-layered pattern of SCAP but had some similar histopathologic features to SCAP. Decapitation secretion was apparent and there was positive immunoreactivity to epithelial membrane ant igen and human milk fat globules subclass 2. SCACP is a rare cutaneous tumo r but nevertheless represents a specific dermatopathologic entity.