Sinonasal undifferentiated carcinoma with orbital invasion - Report of three cases

Purpose: To report three patients with sinonasal undifferentiated carcinoma (SNUC) that invaded the orbit. Methods: Retrospective small case series. The clinical, radiographic, and pathologic features of three patients with SNUG were reviewed. Results: Three patients with SNUC that invaded the orbit were evaluated. A biopsy was performed on the tumors, which were composed of small, hyperchromatic cells with numerous mitoses and areas of necrosis. Immunohistochemical staining was positive for cytokeratins AE1,3, epithelial membrane antigen, and neuron-specific enolase in all three tumors. Electron microscopic examination showed absence of neurosecretory granules and presence of basement membrane production. Two patients were treated with surgical resection and postoperative chemotherapy and/or radiation. One patient was treated with preoperative radiation and chemotherapy. Conclusions: Sinonasal undifferentiated carcinoma is a high-grade tumor that arises in the nasal and paranasal sinuses and may invade the orbit. SNUG should be distinguished from other small,, round, blue cell tumors, in particular, esthesioneurablastoma.