[Clinicopathologic and ultrastructural studies of olfactory neuroblastoma].

The clinicopathologic and ultrastructural studies of 12 cases of olfactory neuroblastoma were made. The ages of patients ranged from 2 to 58 years with a mean of 32. Eleven cases occurred in men and 1 case in woman. An acidophilic fibrillary intercytoplasmic background was present in every case. Its amount varied focally. Ultrastructurally, the acidophilic fibrillary background was composed of neuronal cell processes. Homer-Wright rosettes were found in 7 cases, Flexner type rosettes in 4 cases, 3 of which shared both Homer-Wright and Flexner type rosettes. Almost all cases with rosettes also had apparent acidophilic fibrillary intercytoplasmic background. So, we think that acidophilic fibrillary intercytoplasmic background was the most useful diagnostic feature by light microscopic observation. The diagnosis of olfactory neuroblastoma by electron microscopy was mainly based on neuronal processes, neurosecretory granules, microtubules, neurofilaments, synaptic-like junctions and occasionally both microvilli and olfactory vesicles at the luminal borders of Flexner type rosettes.