[Olfactory neuroblastoma: a histopathological ultrastructural and immunohistochemical study of 11 cases].

Eleven cases of olfactory neuroblastoma (ONB) were studied histopathologically, ultrastructurally and immunohistochemically. Light microscopical examination showed the tumor cell nests separated by fibrous connective tissue (present in 10/11 ONB), Homer-Wright rosette and/or Flexner rosette (9/11 ONB) and acidophilic fibrillary background (8/11 ONB). Ultrastructurally, there were neurosecretory granules (2/2 ONB) and neurofibrils (1/2 ONB) in cytoplasm of tumor cells. A panel of antibodies were used to characterize the immunohistochemical staining profile of ONB. The following results were obtained for the 11 neoplasms that were immunostained: NSE 11/11 (+), S-100 3/11 (+), Vimentin 4/11 (+), Keratin 1/11 (+) and NF, EMA, CEA, LCA all negative respectively. The significance of the morphological and immunohistochemical features of ONB in diagnosis and differential diagnosis were discussed.