[Case of acute interstitial pneumonia that responded to therapy but relapsed six months later].

A 66-year-old man was admitted because of general fatigue. A chest computed tomography showed bilateral alveolar consolidation and ground glass opacities. Although we treated him with broad-spectrum antibiotics, his symptoms and chest image findings did not improve. Thoracoscopic lung biopsy (rS2, S9) was performed. The specimens showed obstructive type intraluminar organization and interstitial inflammatory thickening. Membranous organization was seen in a limited area. The etiology of the illness could not be identified. We diagnosed acute interstitial pneumonia (AIP) because the specimens showed diffuse alveolar damage pattern (DAD/P) and because of unknown etiology. The symptoms and chest image findings were improved on treatment with corticosteroid and cyclophosphamide. However, he was readmitted because of dyspnea 6 months later after the thoracoscopic lung biopsy. Chest computed tomography showed bilateral diffuse ground glass opacities and reticular opacities in both lower lobes. We employed mechanical ventilation, antibiotics, sivelestat sodium hydrate and steroid pulse therapy, but he died without any response to treatment. The findings of autopsy revealed DAD/P accompanied by a new lesion mainly composed of membranous organization and hyaline membrane. We believe this case is valuable when considering the variety of responses to treatment of AIP and prognosis.