Syringocystadenoma Papilliferum and Nevus Sebaceous of Jadassohn: Disentangling Rare Simultaneous Pathologies.

Nevus sebaceous of Jadassohn (NSJ) is a cutaneous benign hamartoma that has been associated with the development of malignant cutaneous tumors such as basal cell carcinoma (BCC). Its coexistence with benign cutaneous tumors has also been reported, while differential diagnosis is considered challenging due to comparable characteristics. Syringocystadenoma papilliferum (SCAP) is a rare benign adnexal tumor and its coexistence with NSJ constitutes an unusual entity, which may lead to diagnostic uncertainty and warrants histopathological examination due to potential malignant transformation. We report a case of a syringocystadenoma papilliferum in a 42-year-old female which developed over a longstanding nevus sebaceous of Jadassohn, presenting as an ulcerated nodule encircled by a hairless plaque on the scalp, a clinical association that presents diagnostic challenges and can resemble malignant skin tumors. Herein, this case highlights the importance of clinical suspicion and complete surgical excision as well as histopathological evaluation of evolving lesions to establish diagnosis and prevent the development of malignant neoplasms.