Sinonasal Undifferentiated Carcinoma (SNUC)


This is a rare tumour of the sinonasal region, but is more common in men.

Aetiology and Pathogenesis

Aetiology is not known; it is not associated with Epstein-Barr virus (unlike nasopharyngeal undifferentiated carcinoma).

Natural History

The tumour is rapidly progressive and invades the nasal cavity, paranasal sinuses, orbit and often the cranial vault. Distant metastases can occur.

Clinical Presentation

Presentation can be rapid with patients developing proptosis and visual loss over a matter of weeks.

Tumour Features


This tumour is typically fungating and locally destructive.


The tumour does not show squamous or glandular differentiation. Cells are typically arranged in sheets, lobules or nests. There are numerous mitoses, with haemorrhage and necrosis usually present.


Cytokeratins are usually positive and allow diagnosis of this tumour. Immunohistochemistry for neuron specific enolase (olfactory neuroblastoma), leukocyte specific antigen (lymphoma), melan-A/S100 (melanoma) and chromogranin/synatophysin (neuroendocrine tumours) is usually negative.