Nose, paranasal sinuses, nasopharynx

Question 1

What are the categories of tumours of the nasal cavity/paranasal sinuses/skull base according to the WHO classification?

Answer 1

1. Carcinoma, including:SCC (keratinising, non-keratinising, sarcomatoid, lymphoepithelial), SNUC, NUT carcinoma, Neuroendocrine carcinoma, Adenocarcinoma: including ITAC, non-ITAC
2. Sinonasal papillomas (everted, inverted, oncocytic)
3. Respiratory epithelial lesions (REAH, seromucinous hamartoma)
4. Salivary gland tumours
5. Soft tissue tumours (benign - leiomyoma/schwannoma, borderline - SFT, glomangiopericytoma, malignant - biphenotypic sinonasal sarcoma, SS, angiosarc, MPNST, etc)
6. Other (meningioma, ameloblastoma, chondromesenchymal hamartoma)
7. Haematolymphoid (Extranodal NK/T cell lymphoma)
8. Neuroectodermal/melanoma (Ewings/PNET, ONB)

Question 2

What is the differential diagnosis of poorly differentiated neoplasms in the sinonasal tract?

Answer 2

1. Olfactory neuroblastoma (negative/focal epi markers, syn+, EBV- (S100+ sustenc cells, calret+))
2. SNUC (LMWCK+, neg/focal syn, EBV- (p63/40 +/-/patchy))
3. NUT (epi markers+, syn-, EBV- (CD34+/-, NUT translocation, p63/p40+))
4. SMARCB1-deficient sinonasal carcinoma (LMWCK+, syn -/focal+, EBV-, INI1 negative)
5. Lymphoepithelial ca/NPC (HMWCK+, EBV+, p63/p40+)
6. NK/T-cell lymphoma, nasal type (epi -, CD56+/NE markers -, EBV+, cytotoxic+, CD2+)