[Lung cancer detected in a patient under age 40 treated for pneumothorax].

We report a case of lung cancer in a relatively young patient who presented pneumothorax. A 31-year-old man complaining of pressure in his left chest was admitted with left pneumothorax disclosed on X-ray film. Although pleural drainage was performed for a week, the left lung did not expand well, and surgical treatment was required. During surgery, a tumor (1.5 x 1.0 cm in size) was discovered in the upper lobe of the left lung (S3). Histopathological examination revealed that it was a large cell carcinoma. People under the age of 40 account for only a small fraction of the entire lung cancer patient population. Pneumothorax occurs together with lung cancer, especially in people under age 40. We reasoned that lung cancer should be considered a possible complication in patients under 40 who experience recurrent or prolonged bouts of pneumothorax.