Abstract
We herein report a fatal case of invasive mucinous adenocarcinoma (IMA) with acute respiratory distress syndrome (ARDS) diagnosed based on autopsy findings. A 76-year-old man presented with severe respiratory discomfort on admission. Computed tomography (CT) revealed a peripheral distribution of consolidation. Although his respiratory status improved after steroid therapy, re-exacerbation occurred, and the patient died on day 131. A bronchoscopic lung biopsy had shown organizing pneumonia, but a post-mortem examination surprisingly revealed IMA with organizing pneumonia. IMA presenting with ARDS as the first symptom is extremely rare.