A 14-year-old girl came to the hospital with her mother, stating that a small birthmark on the scalp had recently started growing rather rapidly. It was increasingly pruritic and caused the patient considerable emotional distress. She was otherwise healthy. On examination a large multilobulated, verrucous lesion was seen on the scalp. The findings were consistent with nevus sebaceus. These lesions have a predilection for the scalp and typically appear early in life as a solitary, hairless patch or small plaque. Often they do not cause problems until the patient reaches adolescence, as hormonal factors induce a verrucous or nodular change and the lesion grows in size, occasionally rather dramatically. Given the size and location of the lesion and the risk of malignant transformation, especially to basal-cell carcinoma, later in life, the patient was referred to plastic surgery for excision. The lesion was successfully excised, and histologic examination confirmed the diagnosis of nevus sebaceus of Jadassohn.