Female, 26 years old, with a tender left parotid mass. Any elongated, T2 hyperintense lesion is evident within the superficial left masticator muscle measuring 20 x 6 mm in transaxial dimension and up to 9 mm in the craniocaudal dimension. This lesion demonstrate mild intrinsic T1 hyperintensity with avid superimposed enhancement. Within the anterior portion of the lesion, there is a suggestion of multiple small cystic spaces with fluid-fluid levels.The above lesion approaches but does not clearly involve or arise from the left parotid gland. The salivary glands are morphologically unremarkable with no evidence of any masslike lesion or pathologic enhancement. The thyroid is free of focal suspicious lesions. No pathologic adenopathy is detected in the neck. The aerodigestive mucosa is unremarkable. Bone marrow signal characteristics are within normal limits.
A lesion is identified within the superficial aspect of the masseter muscle on the left with T1 imaging characteristics suggestive of the presence of intralesional fat, blood product or slow vascular flow. The anterior portion of the lesion seems to show multiple small cystic spaces with fluid-fluid levels.Given the imaging characteristics, and the apparent intramuscular location of the lesion, the possibility of a venous malformation or some other vascular anomaly is favored. A recent intralesional hemorrhage could account for new tenderness on palpation. No significant surrounding inflammation is seen to suggest an infectious etiology. A neoplastic lesion is considered less likely.