Abstract
A 71-year-old woman with arthralgia and lung fibrosis was referred to Mito Kyodo General Hospital (Mito, Japan) for a mass, which was incidentally observed on a chest radiograph. The chest computed tomography scan demonstrated fibrotic lesions in the lower lobes of the lung and a nodule in the left upper lobe. The serum levels of myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA) and proteinase 3 (PR3)-ANCA were 60.3 and 7.5 U/ml, respectively. A transbronchial biopsy obtained from the nodule in the left upper lobe of the lung revealed a lung adenocarcinoma and the patient underwent standard upper lobectomy of the left lung. Subsequent to the resection, the serum levels of PR3-ANCA and MPO-ANCA returned to 10.0 and <1.0 U/ml, respectively. Notably, titers of antinuclear antibodies were also decreased during the postoperative course. Although elevated serum ANCA levels are rarely seen in lung cancer, they may be associated with the occurrence of lung cancer in certain patients, as observed in the present case.