Co-expression of trkA and p75 neurotrophin receptor in extracranial olfactory neuroblastoma cells

Olfactory neuroblastoma (ON, esthesioneuroblastoma) is a high-grade malignant tumour of neuronal origin. Little is known about the neurobiological behaviour of this tumour. Ten cases of ON and five cases of nasopharyngeal carcinoma were examined for expression of trkA and p75 neurotrophin receptor (p75NTR) using immunohistochemistry and double labelling fluorescence. We found that all ON tissues from 10 cases expressed both trkA and p75NTR at different levels. Double staining revealed that almost all trkA-immunoreactive ON cells also contained p75NTR immunoreactivity. By contrast, no trkA or p75NTR immunoreactivity was detected in nasopharyngeal carcinoma cells from five patients. These results suggest that nerve growth factor may play a role in the generation of ON and staining of trkA and p75NTR may assist in the diagnosis of ON.