Histogenesis of olfactory neuroblastoma. I. Electron microscopy of typical human case

"Olfactory neuroblastoma" covers several types of esthesioneurogenic tumors such as esthesioneuroepithelioma, esthesioneuroblastoma and others. They are thought to be of olfactory mucosal origin and present with typical light microscopical "neurogenic features" e.g. rosettes and/or axon production. Some cases have been analyzed ultrastructurally and contained membrane bound granula like others tumors of the APUD system, originating from the neural crest. Furthermore neuronal differentiation of various degrees has been described. The human case of this contribution did not contain rosettes, but axons could be demonstrated in considerable number by silver impregnation. Electron microscopy could demonstrate the presence of dendritic processes with microtubuli and filaments as well as abundance of secretory granules of 1800 A. The comparison with the up to now published findings shows that the production of dense core granules is the most constant ultrastructural feature in these tumors; however, additional ultrastructural features in typical human cases as here presented, earlier experimental results and few human descriptions show, that DCV production is not essential for olfactory neuroblastoma. This might shed new light on the histogenesis of these tumors.