Chronic pyothorax associated with pulmonary tuberculosis was recently proposed to be one of the predisposing factors of angiosarcoma arising in the chest wall. Separately, several authors have reported pleural angiosarcoma that has a close resemblance to mesothelioma, the latter having no apparent association with a history of pyothorax. I present a detailed pathologic description of an autopsy case of thoracic angiosarcoma arising after long-standing tuberculous pyothorax, for the purpose of better illustrating this condition. In this case, the main tumor mass was situated on the soft tissue of the chest wall outside the rib girdle. On the pleuropulmonary tissue, tumor infiltration was grossly observable as a dark patch, 2 cm in diameter, on the outer surface of the wall of the pyothorax (pleural peel). Infiltration of the tumor was found in the soft tissue just outside of the peel and in the attached rib. However, the tumor was not found in the peel itself, nor was it found in the necrotic content of the pyothorax. This case suggests that angiosarcoma associated with pyothorax is not similar to primary pleural angiosarcoma and shows the rather ordinary feature of the tumor's arising in the soft tissue.