Basal cell adenomas of the parotid gland: CT and MRI features

Objective: To investigate the CT and MRI features of basal cell adenoma of the parotid gland. Methods: CT and MRI features of 9 basal cell adenoma cases (4 men and 5 women, median age 58) confirmed by operation and pathology were reviewed retrospectively. All CT and MR images were retrospectively evaluated with respect to location, size, morphology, margin, CT density / MRI signal intensity and enhancement behavior. Results: Each of the 9 patients had only 1 tumor. Eight lesions were located in the superficial lobe and 1 in the deep lobe. Seven tumors were round without lobular appearance, and 2 tumors were elliptic with small lobular appearance. All the 9 lesions were well circumscribed with smooth contours. A capsule-like rim with low intensity on MRI was observed in 2 lesions, and a rim with high intensity on T1WI and T2WI was detected in another lesion. These 3 lesions showed low intensity on T1WI and T2WI with heterogeneously strong enhancement and delayed enhancement. Four lesions showed cystic areas in the center with mural nodules on CT, which were moderately or obviously enhanced (the mean increase of CT values: 65.5 HU), and 2 lesions showed homogeneous enhancement. Conclusion: Basal cell adenoma of parotid gland should be first considered when the old women had single round lesion located in the superficial lobe with smooth contour and low intensity on T2WI, especially when cystic areas were observed in the center with mural nodules on CT/MR. (authors)