The diagnosis of ONB was favoured over a neuroendocrine carcinoma due to the presence of neuropil-like material, S100 positive sustentacular cells focally within the tumour, positivity of the neuroendocrine component for calretinin and negativity for p63, location of the lesion arising out of the left olfactory groove, and the presence of neuroendocrine hyperplasia. This evidence concerns the gene CALB2 and neoplasm.