Clear cell rhabdomyosarcoma of the nasal cavity and paranasal sinuses.

This report describes two cases of alveolar rhabdomyosarcoma of the nasal cavity with unusual histological appearances mimicking clear cell carcinoma. The closely packed tumour cells were polygonal and arranged in sheets and packets. They had an appreciable amount of clear cytoplasm due to accumulation of glycogen. The diagnosis of rhabdomyosarcoma was confirmed by positive staining for desmin and myoglobin. Rhabdomyosarcoma should be included in the differential diagnosis of nasal clear cell tumours, particularly in young adults. A correct diagnosis is important, because chemotherapy is indicated even for apparently localized disease.