[Acute cholecystitis due to microscopic polyangiitis:a case report].

A 78-year-old man with chief complaints of cough and lower limb numbness was admitted to our hospital. Serum myeloperoxidase-antineutrophil cytoplasmic antibody titer (MPO-ANCA) was elevated (48.8U/ml), and a diagnosis of microscopic polyangiitis (MPA) was made. After admission, the patient developed a fever and right upper quadrant pain. Ultrasonography and computed tomography revealed an acute cholecystitis of unknown cause, and laparoscopic cholecystectomy was performed. Histopathological examination of the resected gallbladder revealed necrotizing vasculitis along with the infiltration of eosinophils, lymphocytes, and plasma cells around the small arteries in the muscular layer of the gallbladder, which are characteristics of MPA.