SINONASAL UNDIFFERENTIATED CARCINOMA - CT AND MR-IMAGING OF AN UNCOMMON NEOPLASM OF THE NASAL CAVITY

PURPOSE: To determine the computed tomographic (CT) and magnetic reson ance (MR) imaging appearance of sinonasal undifferentiated carcinoma. MATERIALS AND METHODS: Findings from 11 patients with histopathologica lly proved sinonasal undifferentiated carcinoma were retrospectively r eviewed. All 11 patients had undergone CT, and six of them had undergo ne MR imaging. RESULTS: The tumors usually were large (larger than 4 c m in maximum dimension in eight patients), had poorly defined margins, and arose within the ethmoid sinuses and superior nasal cavity. The a ggressive nature of the tumor was demonstrated by bone destruction (n = 10) and by invasion of adjacent structures, including paranasal sinu ses (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 t o varying degrees. They tended to be noncalcified (n = 10) and often c aused sinus obstruction (n = 10). MR signal intensity of the lesions w as isointense to muscle on T1-weighted images in all six patients and iso- to hyperintense on T2-weighted images in five patients. Heterogen eous enhancement of tumors was seen on gadolinium-enhancedimages. CONC LUSION: Sinonasal undifferentiated carcinoma cannot be distinguished f rom other tumors of this region (with the possible exception of melano ma) on the basis of imaging features.