Collision tumor of sebaceous carcinoma and squamous cell carcinoma of the eyelid: Case report

Background: Collision tumors are rare clinical entities that two heterogeneous neoplasms are concurrently adjacent to each other at the same location. The association of a squamous cell carcinoma and a malignant adnexal tumor is even infrequent. Case presentation: The case of a 79-year-old woman having a slow-growing and painless tumor on the left lower eyelid was presented. The lesion, about 15 mm in diameter, was nodular, irregular, and yellow-discolored. Histopathologic and immunohistochemical findings disclosed concurrence of sebaceous carcinoma as well as squamous cell carcinoma in one specimen. Wide excision of the tumor with frozen section control and eyelid reconstruction were performed. Oncologic survey revealed no other lesion. At 6-month follow-up, no evidence of recurrence or metastasis was presented. Conclusion: Collision tumor composed of sebaceous carcinoma and squamous cell carcinoma in eyelid may be the first case described in the literature. For increasing accuracy of diagnosis and management, a thorough clinical examination and detailed histopathologic analysis, along with multidisciplinary discussion, are prerequisites.