First reported in 1895, nevus sebaceus (NS) is a con genital papillomatous hamartoma most commonly found on the scalp and face. 1 Lesions typically are yellow-orange plaques and often are hairless. Nevus sebaceus is most prominent in the few first months after birth and again at puberty during development of the sebaceous glands. Development of epithelial hyperplasia, cysts, verrucas, and benign or malignant tumors has been reported. 1 The most common benign tumors are syringocystadenoma papilliferum and trichoblastoma. Cases of malignancy are rare, and basal cell carcinoma is the predominant form (approximately 2% of cases). Squamous cell carcinoma (SCC) and adnexal carcinoma are reported at even lower rates. 1 Malignant transformation occurring during childhood is extremely uncommon. According to a PubMed search of articles indexed for MEDLINE using the terms nevus sebaceous, malignancy, and squamous cell carcinoma and narrowing the results to children, there have been only 4 prior reports of SCC developing within an NS in a child. 2-5 We report a case of SCC arising in an NS in a 13-year-old adolescent girl with perineural invasion.
Case Report
A 13-year-old fair-skinned adolescent girl presented with a hairless 2×2.5-cm yellow plaque at the hairline on the anterior central scalp. The plaque had been present since birth and had progressively developed a superiorly located 3×5-mm erythematous verrucous nodule (Figure 1) with an approximate height of 6 mm over the last year. The nodule was subjected to regular trauma and bled with minimal insult. The patient appeared otherwise healthy, with no history of skin cancer or other chronic medical conditions. There was no evidence of lymphadenopathy on examination, and no other skin abnormalities were noted. There was no reported family history of skin cancer or chronic skin conditions suggestive of increased risk for cancer or other pathologic dermatoses. Differential diagnoses for the plaque and nodule complex included verruca, Spitz nevus, or secondary neoplasm within NS.
Figure 1. Preoperative photograph showing a hairless 2×2.5-cm yellow plaque at the hairline on the anterior central scalp with a superiorly located 3×5-mm erythematous verrucous nodule raised to an approximate height of 6 mm.