Secondary neoplasms arising from nevus sebaceus: A retrospective study of 450 cases in Taiwan.

Nevus sebaceus is frequently associated with the development of secondary neoplasms. Incidences of malignant transformation vary among different reports and few data is available regarding Asian populations. We aimed to determine the characteristics of secondary tumors developing from nevus sebaceus in a Taiwanese population and to review the published work. Patients with clinically and histologically confirmed nevus sebaceus were identified from 1992 to 2012 in a medical center. Among the 450 cases of nevus sebaceus, 38 secondary neoplasms were noted, accounting for 8.5% of all cases. Benign tumors represented more than 80% of all tumors. Syringocystadenoma papilliferum (2.7%) was the most common benign tumor, followed by trichoblastoma (1.6%) and trichilemmoma (1.6%) whereas basal cell carcinoma (0.9%) was the most frequent malignant tumor on nevus sebaceus and its clinical features were not typical. All the malignant tumors on nevus sebaceus were noted only in adulthood and the mean age of those with basal cell carcinoma was significantly older than that of trichoblastoma (P = 0.028). Our study concludes that malignant transformation is rare in nevus sebaceus and occurs uniquely in adulthood. On the basis of the findings, prophylactic excision of nevus sebaceus can be elective during childhood but is strongly advocated at puberty due to the increased risk of malignant transformation with time.