A clinicopathologic study of folliculosebaceous cystic hamartoma.

Folliculosebaceous cystic hamartoma (FSCH) is a distinctive cutaneous hamartoma of follicular, sebaceous, and mesenchymal components. Only 70 cases of FSCH have been reported in the literature since the original report of 5 cases in 1991. There has been little information reported about the clinicopathologic characteristics of FSCH. We summarize the clinicopathologic features of 153 cases of FSCH that were diagnosed histopathologically at Sapporo Institute for Dermatopathology. The 153 cases of FSCH comprised 92 male and 61 female patients. The typical clinical presentation of FSCH revealed solitary and skin-colored, protruding papules or nodules measuring several millimeters in diameter on the face, especially on the nose, of middle-aged or older persons. These cases fulfilled the common denominators for the histopathologic diagnosis of FSCH as Kimura et al reported. Seven of 153 cases (4.6%) were accompanied by distinctive features of Miescher-type melanocytic nevi. All 7 cases showed lesions on face, especially on or around the nose. We consider that Miescher-type melanocytic nevi play a significant role in the pathogenesis of FSCH, at least in some cases.