A Case of Granulomatosis With Polyangiitis Mimicking Chronic Sinusitis With Polyp.

A diagnosis of granulomatosis with polyangiitis (GPA) can be challenging due to its diverse and nonspecific clinical manifestations, and it is often misdiagnosed as a simple inflammatory disease. Since the nasal septum is the most commonly involved site in the nose, GPA is typically suspected in cases presenting with septal perforation or inflammation. It is very rare for the septum to remain intact while GPA involves only the sinus, which may lead to misdiagnosis as simple sinusitis. A 64-year-old man visited our hospital after being diagnosed with chronic sinusitis at a private clinic. He showed no abnormalities in the septum, but pansinusitis was noted on computed tomography, and GPA was suspected based on a biopsy of a mass resembling a nasal polyp performed in the outpatient setting. The diagnosis of GPA was ultimately confirmed through further laboratory evaluation. Here, we present a case of GPA and review the recently revised diagnostic criteria for GPA.