A Case of Pleuritis Associated With Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis Diagnosed Through Medical Thoracoscopy

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) includes eosinophilic granulomatosis with polyangiitis, granulomatosis with polyangiitis, and microscopic polyangiitis. Pulmonary involvements such as interstitial pneumonia and alveolar hemorrhage are common in AAV, but pleuritis is rare. Here, we report a case of pleuritis associated with AAV. A 68-year-old woman was referred to our hospital because of bilateral wrist and knee pain, Raynaud's phenomenon, and a sclerotic change in her extreme fingers with elevation of proteinase 3 ANCA (PR3-ANCA) and myeloperoxidase-ANCA (MPO-ANCA). From a skin biopsy of her forearms and fingers, we diagnosed that the patient had limited systemic sclerosis. After her first visit at 15 months, she complained of pain in the side of her chest. Her chest X-ray and computed tomography showed left pleural effusion, and local anesthetic thoracoscopy was performed. Histological examination of the pleural revealed granuloma and vasculitis. Based on her symptoms and histological findings, we diagnosed this case as ANCA-associated vasculitis (AAV) and treated it with steroids and intravenous cyclophosphamide successfully. Pleuritis is a rare pulmonary lesion of AAV, and thoracoscopy under local anesthesia is useful for the histological examination of vasculitis.