Sebaceous Carcinoma and Squamous Cell Carcinoma Collision Tumor on the Back: A Case Report

A collision tumor refers to the simultaneous presence of two different tumors from distinct tissue origins at the same or adjacent anatomical sites. We report a case of a 73-year-old female with a back skin lesion, where histology and immunohistochemistry revealed the co-existence of squamous cell carcinoma and sebaceous carcinoma within the same lesion. The lesion was surgically excised with clear margins, and no recurrence or metastasis was observed during a one-and-a-half-year follow-up period.