Histopathological features of fibrous cephalic plaques in tuberous sclerosis complex

Aims Fibrous cephalic plaques (FCPs) in individuals with tuberous sclerosis complex (TSC) may be excised for cosmetic reasons or biopsied to confirm lesion identification and TSC diagnosis. The aim of this study was to determine the range of histopathological features of FCPs. Methods and results A retrospective analysis was conducted on 119 adults with TSC. Twenty‐one lesions from 16 individuals were evaluated by a dermatopathologist. Additionally, we assessed whether lesion colour or histology varied by anatomical location. Seventy‐six lesions were observed in 36 of 119 individuals. Erythematous lesions were more commonly found on the forehead, face or neck than on the scalp (odds ratio = 12.6, P = 0.0001). Thickened and disorganised collagen fibre bundles were present in 95% (20/21) of lesions. Perifollicular fibrosis was observed in 95% (20/21) of lesions, enhanced vascularity was observed in 52% (11/21) of lesions, and features of fibrofolliculoma were observed in 43% (9/21) of lesions. Other abnormalities included features similar to trichofolliculoma, follicular‐derived, infundibular‐type cysts, and abnormally arranged primitive hair follicles. Conclusions FCPs in TSC show thickened bundles of collagen, and hamartomatous changes involving hair follicles. Recognition of these histopathological features may raise the possibility of unsuspected TSC or confirm FCP identification.