Nevus Sebaceus of Jadassohn of the Scalp Clinically Mimicking Syringocystadenoma Papilliferum: A Case Report

Abstract

Nevus sebaceus of Jadassohn is a congenital organoid hamartoma of the pilosebaceous unit that most commonly presents as an alopecic plaque over the scalp and may become thicker or more verrucous with age, occasionally raising concern for secondary adnexal neoplasms. We report the case of a 23-year-old woman who presented to the Department of Dermatology, Venereology and Leprosy, Sree Balaji Medical College and Hospital, with a skin-coloured scalp lesion present since birth and showing gradual increase in size over the preceding 1 year. She had no history of pain, pruritus, discharge, bleeding, trauma, or topical application. Cutaneous examination revealed a solitary, well-defined, non-tender 3 × 3 cm plaque with a mildly cerebriform surface over the left parietal scalp, without ulceration or surrounding inflammation. In view of the recent enlargement and plaque morphology, syringocystadenoma papilliferum arising in a congenital adnexal hamartoma was considered clinically. Histopathological examination, however, confirmed the diagnosis of nevus sebaceus. As there were no clinical or histological features suggestive of secondary neoplasia, the patient was reassured and advised regular follow-up, with instructions to report any further increase in size, nodularity, bleeding, ulceration, or other surface change. This case highlights the importance of considering nevus sebaceus in the differential diagnosis of longstanding congenital alopecic scalp plaques with recent morphological change and underscores the key role of histopathology in establishing the diagnosis and excluding associated neoplasms.