[Primary lung osteosarcoma simulating gastric carcinoma]

The rarest case of primary lung osteosarcoma is described. Despite the fact that an extended clinicoinstrumental study was conducted, the clinicians who interpreted the process to be a destructive gastric carcinoma did not diagnose the site of the tumor. Autopsy identified the unusual form of primary lung malignancy progression with an advanced invasion into the organs on both sides of the diaphragm, including the gastric wall.