Granulomatosis With Polyangiitis Presenting as an Infratemporal Fossa Mass.

Granulomatosis with polyangiitis is a rare autoimmune disease that affects small to medium-sized blood vessels throughout the body. Here, we present a case of an infratemporal mass that was the result of granulomatosis with polyangiitis. A 51-year-old male presented to the emergency department due to right cheek and facial pain that he had been experiencing for 2 to 3 months. An MRI revealed a mass within the right infratemporal and pterygopalatine fossae extending into the inferior right orbital fissure along the maxillary division of the trigeminal nerve (V2) and the vidian nerve causing concern for malignancy. Histology from an endoscopic biopsy demonstrated multiple arteries with luminal obliteration with non-necrotizing granulomas. The patient was started on steroids and immunosuppressive therapy, which improved his symptoms and decreased the size of the residual mass. This case illustrates the need for laboratory testing, imaging, and biopsy of the involved tissue in cases where GPA is suspected to prevent treatment delays that could lead to the destruction of vital organs.