Here, we present a case of a 42-year-old woman who first visited our department in October 20XX after abnormal chest shadows were detected in a medical checkup. A computed tomography scan of the chest revealed multiple pulmonary nodular shadows measuring 2–15mm in size in both the lungs. A surgical lung biopsy was also performed, and histopathological hematoxylin-eosin staining indicated increased proliferation of cells with egg-shaped or oval nuclei. Vascular structures were not observed, although focal vacuoles containing erythrocytes were detected in part. There were few nuclear atypia. The results of immunostaining were negative for cytokeratin (CK) 7, CK20, and thyroid transcription factor 1, and positive for CD31, CD34, and erythroblast transformation-specific-related gene. These results suggested the possibility of vascular tumors. Moreover, epithelioid hemangioma was morphologically suspected as the differential diagnosis. However, the patient was diagnosed with kaposiform hemangioendothelioma since the analyses of multiple pulmonary lesions indicated mediastinal lesions, which tended to proliferate with time. Kaposiform hemangioendothelioma is a moderately malignant vascular tumor that commonly arises in the skin, retroperitoneum, and mediastinum. Furthermore, it predominantly develops in infants and children, and rarely in the lungs of adults.