Simultaneous Development of Three Different Neoplasms of Trichilemmoma, Desmoplastic Trichilemmoma and Basal Cell Carcinoma Arising from Nevus Sebaceus

Nevus sebaceus is a hamartoma of the sebaceous gland that occurs congenitally, from which various secondary tumors can arise with a prevalence of 5%-6%. Benign neoplasms commonly arise from nevus sebaceous, but they have a very low malignant potential. Two neoplasms may occasionally arise within the same lesion, but it is rare for three or more neoplasms to occur in a nevus sebaceus simultaneously. A 61-year-old male patient was admitted to our hospital for a $4cm\times2.5cm$ growing tumor in a verrucous form arising within a periauricular nevus sebaceus in the post auricle of the left ear that had developed 30 years earlier. The nodule was diagnosed as 3 different types of tumors: trichilemmoma, desmoplastic trichilemmoma, and basal cell carcinoma. To our knowledge, this is the first report of the coexistence of three different tumors arising from nevus sebaceous. It contain malignant neoplasm also. Surgeons should be aware of the need for close monitoring and early complete surgical excision of sebaceous nevus in order to improve patient outcomes.