Lung Metastases of Pancreatic Adenocarcinoma Masquerading as Temporary Improvement of Bilateral Diffuse Lung Opacities Following Treatment for Interstitial Lung Disease

ABSTRACT

A 75‐year‐old man presented with bilateral ground‐glass opacities (GGOs) and consolidation on computed tomography (CT). Bronchoalveolar lavage revealed no pathogens or malignant cells. Acute exacerbation of interstitial lung disease was suspected because of rapidly progressive respiratory failure, but steroid pulse therapy was ineffective. After cyclophosphamide treatment, CT showed transient improvement of GGOs and consolidation. Subsequently, worsening bilateral opacities and abnormalities of the main pancreatic duct were detected on CT and magnetic resonance imaging. These radiological findings and sputum cytology indicated lung metastases from pancreatic adenocarcinoma. The autopsy demonstrated lung metastases of pancreatic ductal carcinoma with extensive organizing pneumonia (OP). Although lung metastases from pancreatic cancer are occasional, diffuse bilateral opacities mimicking interstitial lung disease are rare. Improvement after prednisolone and cyclophosphamide may have reflected effects on both OP and metastases. Lung metastases should remain an important differential diagnosis even when bilateral GGOs and consolidation respond to treatment.