A Boy with a Bald Spot on his Scalp, Returns

Dr Jonathan Schneider reviews a case here from his days as a Navy doctor. A patient he saw as a baby returns, with his family, as a young teen. A scalp lesion noted early in the boy's life is still present and has grown in size. The mother is concerned because a) the lesion has gotten worse, and, b) she had been advised when it was first detected, to have it removed before the boy reached puberty. He is 13-years-old.What is your diagnosis of the expanding growth? How would you advise mother and son to proceed at this point?         Resources (in alphabetical order)- Ankad BS, Beergouder SL, Domble V. Trichoscopy: The best auxiliary tool in the evaluation of nevus sebaceous. Int J Trichology. 2016;8: 5–10.- Cribier B, Scrivener Y, Grosshans E. Tumors arising in nevus sebaceous: A study of 596 cases. J Am Acad Dermatol. 2000;42(2 Pt 1):263-8.- Falto-Aizpurua LA, Griffith RD, Nouri K. Josef Jadassohn A dermatologic pioneer. JAMA Dermatol. 2015;151:41. doi:10.1001/jamadermatol.2014.3187.- Jaqueti G, Requena L, Sanchez Yus E. Trichoblastoma is the most common neoplasm developed in nevus sebaceus of Jadassohn: a clinicopathologic study of a series of 155 cases. Am J Dermatopathol. 2000;22:108-18.- Leung AKC and Barankin B. Nevus Sebaceous. Austin J Pediatr. 2014;1:1006.- Miller CJ, Ioffreda MD, Billinglsey EM. Sebaceous carcinoma, basal cell carcinoma, trichoadenoma, trichoblastoma, and syringocystadenoma papilliferum arising within a nevus sebaceus.  Dermatol Surg. 2004;30:1546–1549.- Moody MN, Landau JM, Goldberg LH. Nevus sebaceous revisited.  Pediatr Dermatol. 2012;29:15–23.- Namiki T, Miura K, Ueno M. Four different tumors arising in a nevus sebaceous. Case Rep Dermatol. 2016 Jan-Apr; 8(1): 75–79.