Morphologic diversity of syringocystadenocarcinoma papilliferum based on a clinicopathologic study of 6 cases and review of the literature.

Syringocystadenocarcinoma papilliferum is an extremely rare cutaneous adnexal neoplasm. The purpose of our investigation was to study a series of syringocystadenocarcinoma papilliferum to document morphologic variations of the neoplasm. This is a light-microscopic study of 6 cases of syringocystadenocarcinoma papilliferum obtained from the combined archival, institutional, and consultations files of the authors over 60 years, complemented by a literature review. Syringocystadenocarcinoma papilliferum invariably occurred in association with syringocystadenoma papilliferum and presented as an in situ adenocarcinoma and/or invasive adenocarcinoma. Additionally, an invasive component was represented by squamous cell carcinoma. Variable present features included pagetoid migration of the neoplastic cells, dirty necrosis, mucinous ductal metaplasia, and ductal changes analogous to those seen in the breast. The ductal changes included patterns identical to columnar cell change (flat epithelial atypia), usual ductal hyperplasia, atypical ductal hyperplasia, and ductal carcinoma in situ. A combination of the above patterns in a single lesion was noted. It is concluded that morphologic diversity of syringocystadenocarcinoma papilliferum is substantial. Its association with the benign counterpart and ductal changes suggests a transformation that may involve usual ductal hyperplasia-atypical ductal hyperplasia-(ductal) adenocarcinoma in situ-invasive adenocarcinoma pathway.