Lung cancer development in the patient with granulomatosis with polyangiitis during long term treatment with cyclophosphamide: first documented case.

A 65-year-old man was diagnosed with granulomatosis with polyangiitis (GPA) at the age of 47, when cytoplasmic anti-neutrophil cytoplasmic antibody (C-ANCA) serology was positive, and he had multiple nodular shadows in both lungs. He had been treated with prednisolone, cyclophosphamide (CPA) and plasma exchange. At the age of 64, a nodular shadow was newly detected in the right lower lung field and serum tumour marker increased. Subsequent positron emission tomography/computed tomography scan demonstrated accumulations of fluorodexyglucose (FDG) in the same area, mediastinum lymph nodes, thoracic wall, right iliac bone, and right retroperitoneum. The diagnosis of squamous cell lung cancer cT2bN2M1b Stage4 was made with endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). There are no reports of cases that lung cancer has developed with GPA during the long-term treatment with CPA. We suggest that in such patients, the differential diagnosis should include not only the relapse of GPA, but also the rare possibility of development of carcinomas.