Imaging characteristics of arteriovenous malformations simulating vascular tumors of the temporalis muscle: a report of two cases.

Arteriovenous malformations (AVMs) of the temporalis muscle are an extremely rare subgroup of head and neck AVMs. The authors report two cases presenting with temporal fossa tumor-like lesions. MRI demonstrated enlargement of the temporalis muscle with hypointensity on T1, hyperintensity on T2 and moderate contrast enhancement. Angiography shows slow arteriovenous shunting with a dense capillary blush of the entire muscle before draining into facial veins. The arterial supply is characteristic of being restricted to the temporalis muscle.