A case of squamous cell carcinoma of the lung with a high titer of proteinase 3 antineutrophil cytoplasmic antibody

: A 57-year-old man who had a history of sinusitis was admitted to Ryugasaki-Saiseikai hospital in April 2002 because of productive cough and bloody sputum. Chest radiographs and CT scans showed mediastinal lymphadenopathy and a solitary mass lesion with an irregular margin and cavity in the left lower lung field. Proteinase 3 antineutrophil cytoplasmic antibody (PR3 ANCA) was positive, and this is a sensitive and specific indicator of Wegener's granulomatosis. The pathological findings from transbronchial biopsy revealed squamous cell carcinoma of the lung, without the presence of vasculitis, accompanied by Wegener's granulomatosis. A partial response was finally obtained after three courses of paclitaxel and carboplatin. The serum level of PR3 ANCA decreased from 142 EU to 16 EU. This case appears to have had parallel time courses of progression of squamous cell carcinoma of the lung and changes in serum PR3 ANCA level. This is of importance in considering the relationship of lung cancer and paraneoplastic vasculitis.