Sinonasal Squamous Cell Carcinoma

Michelle A. Michel, MD

Key Facts

Terminology

Malignant epithelial tumor with squamous cell or epidermoid differentiation

Imaging

Location: Maxillary antrum involved > 80%
CT findings
- Soft tissue density mass with irregular margins
- Aggressive bone destruction
MR findings
- ↓ T2 signal due to ↑ N:C ratio
- Enhances to lesser degree than other sinonasal malignancies
Multiplanar enhanced MR optimal for tumor mapping, detection of PNTS & nodes

Top Differential Diagnoses

Sinonasal adenocarcinoma
Sinonasal undifferentiated carcinoma (SNUC)
Invasive fungal sinusitis
Sinonasal non-Hodgkin lymphoma
Wegener granulomatosis

Pathology

Risk factors: Inhaled wood dust, metallic particles, chemicals, HPV, inverted papilloma
- Formaldehyde & asbestos exposure may ↑ risk
- Human papilloma virus, pre- or coexisting inverted papilloma ↑ risk

Clinical Issues

Symptoms mimic chronic sinusitis & delay diagnosis
Age at presentation: 50-70 years old
Most common malignancy of sinonasal area
15% maxillary sinus SCCa have malignant adenopathy
Overall 5-year survival: 60%
Combined surgery & XRT most common treatment

(Left) Coronal graphic shows the typical features of an aggressive right maxillary SCCa with destruction of the maxillary sinus walls. Extension into the orbit

, maxillary alveolus

, and buccal space

is noted. (Right) Axial CECT shows the typical location and appearance of an antral SCCa. There is extension into the premaxillary soft tissues anteriorly

and through the posterior maxillary wall into the infratemporal fossa

(Left) Axial T1WI MR shows a large antral SCCa. The signal of the mass is similar to other soft tissues. There is extension anteriorly into the premaxillary soft tissues

, medially into the nasal cavity

, and posteriorly into the masticator space

. (Right) Coronal T2WI FS MR in the same patient demonstrates ethmoid sinus involvement

and masticator space extension

. The low T2 signal of this mass is consistent with high cellularity and N:C ratio.

TERMINOLOGY

Abbreviations

Squamous cell carcinoma (SCCa)

Synonyms

Epidermoid carcinoma, transitional carcinoma, nonkeratinizing carcinoma, respiratory mucosal carcinoma

Definitions

Malignant epithelial tumor growing from sinus surface epithelium into sinus lumen with squamous cell or epidermoid differentiation

IMAGING

General Features

Best diagnostic clue
- Aggressive antral soft tissue mass with invasion & destruction of sinus walls
Location
- 75% arise in sinuses; 30% arise primarily in nose
  - Maxillary antrum (85%), ethmoid (10%), frontal/sphenoid (< 5%)
- Radiologist creates presurgical tumor map of spread
  - Medial: Nasal cavity → ethmoid sinuses
  - Anterior: Subcutaneous tissues of cheek
  - Posterior: Retroantral fat pad, pterygopalatine fossa (PPF) & masticator space
  - Lateral: Malar eminence & subcutaneous tissues
  - Superior: Through orbital floor into orbit proper or via PPF → inferior orbital fissure → orbit
  - Perineural tumor spread (PNTS): Inferior orbital nerve or PPF → V2 (foramen rotundum) → cavernous sinus
Size
- Usually fills maxillary antrum
Morphology
- Well defined to poorly defined with irregular, spiculated margins