Purpose: To determine the computed tomographic (CT) and magnetic resonance (MR) imaging appearance of sinonasal undifferentiated carcinoma.
Materials and methods: Findings from 11 patients with histopathologically proved sinonasal undifferentiated carcinoma were retrospectively reviewed. All 11 patients had undergone CT, and six of them had undergone MR imaging.
Results: The tumors usually were large (larger than 4 cm in maximum dimension in eight patients), had poorly defined margins, and arose within the ethmoid sinuses and superior nasal cavity. The aggressive nature of the tumor was demonstrated by bone destruction (n = 10) and by invasion of adjacent structures, including paranasal sinuses (n = 10), anterior fossa (n = 7), orbits (n = 4), pterygopalatine fossa (n = 2), parapharyngeal space (n = 1), and cavernous sinus (n = 1). On contrast material-enhanced CT scans, all tumors were enhanced to varying degrees. They tended to be noncalcified (n = 10) and often caused sinus obstruction (n = 10). MR signal intensity of the lesions was isointense to muscle on T1-weighted images in all six patients and iso- to hyperintense on T2-weighted images in five patients. Heterogeneous enhancement of tumors was seen on gadolinium-enhanced images.
Conclusion: Sinonasal undifferentiated carcinoma cannot be distinguished from other tumors of this region (with the possible exception of melanoma) on the basis of imaging features.