Background: Squamous cell carcinoma (SCC) as the malignant component of carcinoma ex pleomorphic adenoma (CXPA) occurring in upper lip is rare.
Case report: A 55-year-old male patient presented with an asymptomatic mass of the upper lip that had noticed 8 years previously. The mass was clinically suspected to be a benign salivary gland tumor based on palpation and magnetic resonance imaging findings. A needle biopsy was then carried out, and the pathological diagnosis was pleomorphic adenoma. The tumor was removed under general anesthesia. Histopathological examination revealed well-demarcated tumor tissues showing typical histologic features of pleomorphic adenoma. However, SCC tissue with several mitotic figures was found in the central area of the tumor tissue. The tumor was finally diagnosed as CXPA. There was no evidence of recurrence or metastasis 6 years postoperatively.
Conclusion: This is the first report of CXPA of the upper lip with an unusual malignant component of SCC.