BACKGROUND: Carcinosarcomas, also known as spindle cell carcinomas, are rare and highly aggressive tumors characterized by dual histologic differentiation of squamous cell and mesenchymal cell tumors. Occurrence of carcinosarcoma in maxillary sinus is very rare, with only 11 cases reported since 1957. The small number of reported cases creates an obstacle to the increased understanding of the behavior, prognosis, and therapeutic management of this tumor.

CASE REPORT: A 52-year-old man presented with a 2-month history of right nasal obstruction. Computed tomography (CT) and magnetic resonance imaging (MRI) showed opacified right frontal, sphenoid, ethmoid, and maxillary sinuses with soft tissue density and expansion of the mass with erosion of the right lateral maxillary wall. Functional endoscopic sinus surgery (FESS) was done and histopathology revealed multiple fragments of nasal mucosa lined by stratified hyperplastic squamous epithelium with an increased degree of dysplasia and pleomorphism and a second spindle cell high-grade neoplastic growth with bizarre giant cells and abnormal mitotic figures. Consistent with carcinosarcoma, immunohistochemistry showed strong positive staining for vimentin in the spindle cell component and strong positive staining for cytokeratin markers in the epithelial cell component. The patient underwent right total maxillectomy with postoperative chemoradiation therapy and survived for 1 year.

CONCLUSIONS: Carcinosarcoma of the maxillary sinus is a rare disease with non-specific symptoms; it usually presents in the advance stage and is associated with poor patient prognosis. This case indicates that surgical intervention with postoperative chemoradiotherapy improves patient prognosis and should be considered as the standard therapeutic modality.

Keywords: Diagnosis, Differential, Carcinoma - surgery, Endoscopy - methods, Magnetic Resonance Imaging, Maxillary Sinus Neoplasms - surgery, Tomography, X-Ray Computed