Pleomorphic carcinoma of the lung in which the sarcomatous element grew rapidly: a case report.

We report a case of pleomorphic carcinoma of the lung that showed a rapid growth. The patient was a 77-year-old female with an abnormality detected in her chest radiograph during a screening examination, but a definite diagnosis could not be obtained based on a needle biopsy guided by CT. After one month, the tumor had continued to grown rapidly and lung cancer was strongly suspected, so the patient underwent surgery. The intraoperative diagnosis demonstrated it to be a pleomorphic carcinoma of the lung in which a squamous element and a sarcomatous element were mixed; and a right lower lobectomy and lymphadenectomy were performed. In a pathological examination after surgery, the tumor was found to be composed of a sarcomatous element that had a high MIB-1 index of 30%, and this was believed to be the cause of the rapid growth.