MRI and CT features of head and neck myoepithelioma: comparison with parotid pleomorphic adenoma.

Purpose: To evaluate the MRI and CT features of head and neck myoepithelioma in comparison with parotid pleomorphic adenoma.

Methods: This retrospective study included 11 patients with histopathologically confirmed myoepithelioma of the head and neck and 103 patients with pleomorphic adenoma of the parotid gland, all of whom underwent preoperative MRI. Among them, seven patients with myoepithelioma and 29 with pleomorphic adenoma also underwent preoperative CT. MRI and CT findings were compared between the two groups.

Results: Multinodular configuration (27% vs. 4%), mild hyperintensity relative to the spinal cord on T2-weighted images (91% vs. 48%), and focal unenhanced areas on fat-suppressed contrast-enhanced T1-weighted images (100% vs. 47%) were significantly more frequent in myoepithelioma than in pleomorphic adenoma, respectively (p < 0.05). In contrast, marked hyperintensity relative to the spinal cord on T2-weighted images (46% vs. 9%), higher signal intensity ratios on T2-weighted images (1.68 ± 0.47 vs. 1.40 ± 0.39), and higher apparent diffusion coefficient (ADC) values (1.68 ± 0.36 vs. 1.38 ± 0.23 × 10^-3 mm²/s) were significantly more common in pleomorphic adenoma than in myoepithelioma, respectively (p < 0.05). Contrast-enhanced CT attenuation was significantly higher in myoepithelioma than in pleomorphic adenoma (93.3 ± 10.5 vs. 59.2 ± 22.8 HU, p < 0.05).

Conclusions: Although MRI and CT features of myoepithelioma and pleomorphic adenoma can overlap, the presence of a multinodular configuration, focal unenhanced areas, lower T2 signal intensity, lower ADC values, and higher contrast-enhanced CT attenuation may aid in differentiating myoepithelioma from pleomorphic adenoma.