Lichen Planopilaris Developing at the Margins of a Sebaceous Nevus of Jadassohn: Co-existence or Etiologic Association?

Sebaceous nevus (SN), is a skin hamartoma, combining a variety of epidermal, follicular, sebaceous, and apocrine abnormalities. Although usually present at birth, it may become apparent later in life appearing as a yellowish-brown, verrucous plaque with alopecia. SN is implicated with secondary tumors arising on the hairless plaque during the adulthood. Lichen planopilaris is a common, primary lymphocytic scarring alopecia of unknown etiology, characterized by lichenoid/interface perifollicular lymphocytic infiltrate occurring at the level of the infundibulum and the isthmus. Here, we present a case of a 48-year-old Caucasian male with lichen planopilaris lesions developing at the periphery of a preexisting SN. Our case raises the question, whether the development of lichen planopilaris was coincidental, or is it indicative of an etiologic association between the lichen planopilaris and SN.