Pulmonary Nocardiosis Caused by Nocardia concava with a Literature Review.

A 68-year-old man was admitted to our hospital with anorexia and leg pain. He was diagnosed with ANCA-associated vasculitis through a renal biopsy. Immunosuppression with two courses of steroid pulse therapies and intravenous cyclophosphamide followed by oral prednisolone at 40 mg/day were administered. About one month after starting the immunosuppression therapy, he complained of hemosputum. Chest computed tomography showed a cavitary lesion in the lung. Cultures from his sputum showed Nocardia species, and we were able to identify the species as N. concava using a 16S rRNA gene sequence analysis. Only three detailed reports of N. concava infection have so far been published worldwide.