Eccrine Poroma and Trichoblastoma Concurrently Arising Within a Nevus Sebaceous of Jadassohn: A Case Report.

Nevus sebaceous of Jadassohn (NSJ) is a congenital, benign hamartomatous lesion characterized by a well-demarcated, hairless, yellowish plaque, usually located on the scalp or face. In adolescence or adulthood, benign or malignant secondary tumors may develop within the nevus sebaceous. The most frequently associated benign tumors include trichoblastoma and syringocystadenoma papilliferum. The presence of an eccrine poroma within a nevus sebaceous is extremely rare, with only six cases documented in the literature. We present a case of a 33-year-old woman with a long-standing alopecic plaque on the scalp that progressively developed into two nodular growths. Histopathological examination of the biopsy revealed features compatible with a sebaceous nevus associated with an eccrine poroma and trichoblastoma. Complete surgical excision of the sebaceous nevus, including both neoplasms, was performed. This study represents one of the few reported cases of an eccrine poroma arising within a nevus sebaceous, underscoring the importance of surveillance and timely excision when indicated.