Idiopathic pseudoaneurysm: a rare cause of parotid mass.

A 77-year-old woman presented with a pulsatile blue-tinged mass over the left parotid, present for 5 years, and slowly enlarging. The size of the mass fluctuated during this period and there was no associated pain. The patient reported no history of surgery or trauma. Vascular lesions are rarely encountered within parotid glands in adults. MRI with contrast demonstrated a soft tissue lesion; despite the presence of feeding vessels it was thought unlikely to be an arterial venous malformation or aneurysmal change. The appearance was thought to be in keeping with an enlarged lymph node or sebaceous cyst. Fine-needle aspiration was obtained using ultrasound guidance and yielded bloody fluid. The lesion was closely related to the superficial temporal artery and a diagnosis of a thrombosed pseudoaneurysm was made. The vessel had thrombosed and the decision was made to enact a watchful waiting policy. The patient will be monitored in the outpatient setting.