Giant, Congenital Folliculosebaceous Cystic Hamartoma: A Case Against a Pathogenetic Relationship With Trichofolliculoma

Folliculosebaceous cystic hamartoma (FSCH) is a rare cutaneous hamartoma consisting of dilated folliculosebaceous units invested in mesenchymal elements. These solitary lesions typically affect adults, have a predilection for the central face or scalp, and remain less than 1.5 cm in greatest dimension. Although giant FSCH variants have been documented, the congenital presentation of a giant FSCH stands in contrast to earlier views of its histogenetic relationship with trichofolliculoma. We describe a giant pedunculated FSCH arising from the posterior neck of a 9-month-old Hispanic male and discuss various aspects of this highly unusual case.