Sinonasal Undifferentiated Carcinoma

Michelle A. Michel, MD

Key Facts

Terminology

Sinonasal undifferentiated carcinoma (SNUC)
Rare, aggressive, sinonasal nonsquamous cell epithelial or nonepithelial malignant neoplasm of varying histogenesis

Imaging

Aggressive sinonasal mass with bone destruction & rapid growth
Large, typically > 4 cm at presentation
Origin most common in nasal cavity with extension into paranasal sinuses; ethmoid origin more common than maxillary
Bone CT: Poorly defined, soft tissue SN mass with aggressive bone destruction
MR: Isointense to muscle on T1
- Low to intermediate T2 signal
- Heterogeneous enhancement with necrosis

Top Differential Diagnoses

Sinonasal squamous cell carcinoma
Esthesioneuroblastoma
Sinonasal non-Hodgkin lymphoma
Sinonasal adenocarcinoma

Clinical Issues

Higher propensity for distant metastases to bone, brain & dura, liver, & cervical nodes than other sinonasal malignancies

Diagnostic Checklist

Imaging features are nonspecific
Tumor growth rate & presence of nodes/distant metastases helpful for suggesting SNUC
Consider extending coverage to evaluate for intracranial (particularly dural) & cervical nodal disease

(Left) Axial NECT demonstrates a large mass in the left maxillary antrum with marked bone destruction and extension into the nasal cavity

, masticator space

, and soft tissues of the cheek. Foci of air are seen within the necrotic portion of this rapidly growing lesion. (Right) Coronal T1WI C+ FS MR in the same patient shows a thick, nodular enhancing rim at the periphery of the mass with central necrosis. There is aggressive invasion of the orbit