The patient was a 53-year-old man whose chief complaint was a dry cough and hemoptysis. Chest X-ray films and computed tomographic scans revealed a hazy shadow with unclear margins in the left middle lobe. A diagnosis of inflammatory pseudotumor was made because transbronchial lung biopsy specimens showed proliferation of plasma cells and lymphocytes. Initially, in response to steroid therapy, his clinical condition and pulmonary infiltration improved, but about 30 days after the start of steroid therapy, hemoptysis occurred and the shadow increased, and therefore left segmentectomy was performed. Histology revealed not only proliferation of acute and chronic inflammatory cells but also changes in the vessels. These pathologic findings were considered to be related to the infiltration shadows and the hemoptysis.