This case report describes the pathological features of pulmonary alveolar proteinosis(PAP) in mouse. Grossly, multiple irregular yellow-grey patches were observed on the lung surface of a C57BL/6 mouse. Histopathologically, the alveolar walls were thickened by type II cell hyperplasia and cellular infiltrates, and the bronchioles and alveolar lumens were filled with amorphous eosinophilic lipoproteinaceous material. This material was positive for Periodic acid-Schiff stain. Gomori methenamine silver staining was negative. Immunohistochemical staining showed that cells in the alveolar wall and lumen were positive for surfactant protein B, chitinase-like protein-3, and CD68. As a result, PAP was diagnosed. This is a rare case of spontaneous PAP in mice, and we report the histopathological characteristics along with the literature.

• Warisraporn Tangchang(College of Veterinary Medicine, Chungnam National University, Daejeon, 34134, Korea)
• Eun-Sang Cho(Chemical Research Bureau, Occupational Safety and Health Research Institute, KOSHA, Daejeon, 34122, Korea)
• Won Kee Yoon(Laboratory Animal Resource Center, Korea Research Institute of Bioscience & Biotechnology, Chungcheongbuk-do, 28116, Korea)
• Hyo-Jung Kwon(College of Veterinary Medicine, Chungnam National University, Daejeon, 34134, Korea)
• Hwa-Young Son(College of Veterinary Medicine, Chungnam National University, Daejeon, 34134, Korea) Corresponding Author