Nevus sebaceus: a clinicopathological study of 168 cases and review of the literature.

Background: Nevus sebaceus is a hamartoma composed of abnormal epidermal and dermal components with clinical and histopathological features that change with aging. Prophylactic excision of the lesion was advised historically considering its potential for giving rise to malignant tumors. However, whether early prophylactic excision should be performed has been questioned recently as most of the tumors have been found to be benign in origin.
Methods: The histopathologic features of 168 patients with nevus sebaceus were reviewed to determine the frequency of different histologic features as well as associated neoplastic growths.
Results: Acanthosis, papillomatosis, and basal layer pigmentation were the most frequent findings. Hyperplastic changes of the sebaceous glands became obvious during the second decade and were present in 60% of the specimens from individuals older than 20. Inflammatory infiltrate was almost invariably present. Skin adnexal changes were frequently noted, including sebaceous gland hyperplasia (93.5%) and primitive hair follicles (76.8%). In 88.5% of scalp lesions, markedly decreased terminal hair was observed. Ectopic apocrine glands were present in 55.4% of specimens, while 24.4% showed anomalous ductal sweat gland structures resembling eccrine hyperplasia. Neoplastic changes were detected in nine cases, including four trichoblastomas, three tricholemmomas, and two syringocystadenoma papilliferums.
Conclusion: Development of malignancies in sebaceus nevi is a rare phenomenon, and decision for excision of the lesion should be made after thorough evaluation of the pros and cons.
(© 2015 The International Society of Dermatology.)