Folliculocystic and Collagen Hamartoma: A Distinct Hamartoma Associated With Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a neurocutaneous disease characterized by cutaneous and extracutaneous hamartomas. Dermatologic evaluation is critical for early diagnosis because mucocutaneous manifestations account for 4 of 11 major and 3 of 6 minor diagnostic criteria. Folliculocystic and collagen hamartoma (FCCH) is a recently described entity associated with TSC. We herein describe the case of a 28-year-old woman with a history of TSC who presented with a scalp lesion present since childhood. Physical examination revealed a solitary, well-circumscribed exophytic tumor over the occipital scalp measuring 9 × 8 cm and covered with comedones and cyst-like structures. Biopsy of the lesion demonstrated thickening of the collagen bundles throughout the dermis, concentric perifollicular and perivascular fibrosis, an increased number of dilated vessels, and keratin-filled cysts lined by the infundibular epithelium. Clinicopathologic correlation was diagnostic for FCCH. The patient was referred for surgical excision. In addition, we review 11 other cases of FCCH previously reported in the literature.