Angiosarcoma is a rare malignant tumor of soft tissue. Because angiosarcoma originates from endothelial cells, it can occur in any organ and shows aggressive clinical features. Most commonly, angiosarcoma initially presents as a cutaneous lesion. Lung metastasis from scalp angiosarcoma can develop pneumothorax. We report a case of multiorgan involvement of an angiosarcoma, including the scalp, initially presenting with hydropneumothorax. Immunohistochemistry analysis of the cells obtained from the study confirmed the pleural invasion of the angiosarcoma.