Pleomorphic sarcoma of maxillary sinus: Clinical report of a patient initially diagnosed with denture-induced fibrous hyperplasia.

Undifferentiated pleomorphic sarcoma is a high-grade soft-tissue malignant tumor that is rare in the head and neck region. A 74-year-old woman displayed a large nodular lesion in the maxillary alveolar mucosa, which was initially identified as denture-related fibrous hyperplasia. Although her prosthodontist has adjusted the maxillary complete denture to relieve pressure on the lesion, it increased in size over time. Computed tomography images of the maxillary sinus showed an extensive destructive lesion. A biopsy was performed, and microscopic examination revealed a poorly differentiated malignancy with numerous spindle cells. Immunohistochemistry reactions were negative for CD45, CD30, CD68, CD34, cytokeratin, S100, desmin, and smooth muscle actin. These findings led to the diagnosis of an undifferentiated pleomorphic sarcoma of the maxillary sinus.