Apocrine poromo: A distinctive case in a patient with nevoid basal cell carcinoma syndrome

Traditionally, poromas have been classified as eccrine neoplasms, but sever al recent reports of poroid tumors with sebaceous, follicular, and apocrine differentiation have challenged this idea. In support of alternative diffe rentiation, a case of an "apocrine'' poroma is reported in a 19-year-old ma n with the nevoid basal cell carcinoma syndrome. A papule on the right chee k, thought clinically to be a basal cell carcinoma, was excised. Anastomosi ng lobules of small uniform basaloid (poroid) cells formed small ductular s tructures lined by eosinophilic cuticles and extended into the superficial reticular dermis. The neoplasm originated from follicular infundibula and w as surrounded by a myxoid stroma. Focally, primitive hair bulb and papillae differentiation was present, and some of the ducts were lined by cells sug gesting decapitation secretion. The histologic pattern and the common embry ologic origin of the folliculosebaceous-apocrine unit support apocrine diff erentiation of this tumor. The association with the nevoid basal carcinoma syndrome appears to be unique. This case, in addition, demonstrates overlap ping features with the infundibulocystic type of basal cell carcinoma commo nly seen in the basal cell nevus syndrome.