(also called olfactory neuroblastoma), uncommon tumour
of neural crest origin that arises from the olfactory mucosa
of the superior nasal fossa. It may present at any age although it peaks twice in the second and fifth decade, respectively. Clinically the tumour
presents as a polypoid
mass that may bleed profusely at biopsy
Tomographic imaging shows a homogeneous enhancing mass, unilaterally located in the superior nasal fossa in initial stages and then extending to nasal sinuses and up beyond the cribriform plate towards the intracranial compartments in more advanced stages. CT shows bone remodelling rather than destruction. On MR the mass presents intermediate signal intensities on all sequences with a tendency to higher signals in T2-weighted sequences. The tumour enhances strongly and homogeneously after contrast administration. Local spread and distant metastases occur in up to 38% of cases and adjuvant chemotherapy and/or radiotherapy is recommended after surgery in higher tumour grades.