Sinonasal Melanoma

Michelle A. Michel, MD

Key Facts

Terminology

Neural crest cell malignancy arising from melanocytes in sinonasal mucosa

Imaging

Soft tissue mass in nasal cavity > paranasal sinuses with bone destruction ± remodeling
- Predilection for nasal septum, lateral nasal wall, & inferior turbinate
MR (melanotic melanoma)
- ↑ T1 & ↓ T2 signal results from melanin, free radicals, metal ions, and hemorrhage
- T2* GRE may show “blooming” when hemorrhage present in SNM
- Avidly enhances due to vascularity in SNM; enhancement may be difficult to appreciate if high pre-contrast T1 signal present

Top Differential Diagnoses

Squamous cell carcinoma
Non-Hodgkin lymphoma
Esthesioneuroblastoma

Clinical Issues

Adult with nasal stuffiness, epistaxis, & pigmented mass identified at nasal endoscopy
- 5th-8th decades most common
- M > F
- > 90% occurs in whites
Poor prognosis with 6-17% chance of 5-year survival
- Mean survival 24 months
- Systemic metastatic disease typically precedes death

Diagnostic Checklist

Look for mass arising in lower nasal cavity with ↑ T1 and ↓ T2 signal

(Left) Coronal graphic shows a darkly pigmented (highly melanotic) mass centered in the nasal cavity. Invasion of the skull base

, orbit

, and lateral nasal wall is seen, but the septum is deviated rather than invaded. Trapped secretions

are noted in the left maxillary sinus. (Right) Coronal bone CT in a patient with left nasal obstruction and epistaxis shows a mass in the left nasal cavity with erosion of the left middle turbinate