[Primary fibrosarcoma of the lung]

A case of primary pulmonary fibrosarcoma in a women of 50 is described as a rare disease which is difficult to diagnose intravitally due to the absence of pathognomonic clinical and roentgenological data. The danger of prolonged time-course observation of the patient with a rounded shadow in the lung is emphasized. The importance of electron microscopic study to specify the morphological diagnosis is demonstrated.