Olfactory neuroblastoma

Despite the fact that olfactory neuroblastoma is considered to be a rare malignant neoplasm of the sinonasal cavity, its frequent inclusion in the differential diagnosis of small-cell neoplasms of the nasal cavity is commonplace. Differential diagnosis of small round tumors solely on the basis of a light-microscopic examination of a hematoxylin and eosin stain often can be impossible. However, immunohistochemical stains such as NSE, S-100, and chromogranin immunostain can be very helpful in diagnosing olfactory neuroblastoma. If special stains are noncontributory, the diagnosis may hinge on supporting evidence from a series of electron micrographs of a properly selected and prepared tumor.