Abstract

Folliculocystic and collagen hamartoma (FCCH) is a rare skin tumor of the tuberous sclerosis complex (TSC). Herein, we present histopathology of five cases of FCCH from two patients. In patient one, an 18-year-old female with TSC presented with three discrete plaques, ranging from 1.5 cm to 10 cm in greatest dimension, involving the scalp. Excisions were performed, and histologic examination of all lesions revealed numerous angiofibromas and widespread follicular changes including distension of follicular infundibulae, disruption of the follicular epithelium, and dense associated neutrophilic and lymphohistiocytic inflammation with surrounding fibrosis. In patient two, a 31-year-old male with TSC presented with four firm plaques and nodules, 1 to 3 cm in greatest dimension, with overlying alopecia. Two lesions were excised, and histologic examination revealed many angiofibromas and follicular changes including infundibulae distended by keratin, rupture with surrounding inflammation and collagenous fibrosis, and displaced hair shafts with foreign body reaction. In these cases, the histopathologic changes involving hair follicles raised the possibility of an inflammatory scarring alopecia, in particular dissecting cellulitis of the scalp, with concomitant angiofibromas. However, in the context of discrete scalp tumors in patients with TSC, the histopathology for these lesions was most consistent with FCCH, a rare and recently characterized lesion of TSC. Clinical correlation is essential for making the diagnosis of FCCH, a lesion which is, in our experience, under-recognized.