Poral neoplasm with combined sebaceous and apocrine differentiation

Poromas have been considered the hallmark of benign eccrine neoplasms. The literature describes six cases of poroma differentiating toward apocrine and sebaceous lineage. We present a benign poroid neoplasm that has the silhouette of hidroacanthoma simplex and also shows sebaceous and apocrine components, The sebaceous attributes include sebocytes, in various stages of maturation, and sebaceous ductal structures. The apocrine component consists of tubules lined by a single or double layer of cuboidal cells that exhibit decapitation secretion. Although present-day techniques cannot unequivocally distinguish apocrine from eccrine differentiation, we think that the poroma-like portion of this neoplasm is most likely apocrine, based on the common embryologic origin of sebaceous, apocrine, and hair follicle structures. We suggest designating these types of tumors as "poral neoplasm" and specifying the type of differentiation: eccrine poral neoplasm, for those that lack follicular and/or sebaceous differentiation, and apocrine poral neoplasm. for those with sebaceous and/or follicular differentiation.