[Olfactory neuroblastoma. Presentation of a case].

Olfactory neuroblastoma is an uncommon and hardly diagnosable neoplasm. The conventional histologic analysis allows generally a diagnosis of undifferentiated carcinoma. The immunohistochemical procedures, particularly the S-100 Protein and the Enolase Neuron-Specific, may contribute to define the diagnosis as well as in a patient recently observed by the authors.