[Pulmonary infarct hardly differentiated from lung cancer--a case report]

A 64-year-old woman experienced high grade fever, chest pain, and hemosputum. She was admitted to a hospital for evaluation of the infiltrate on an chest X-ray. She was diagnosed as having lung cancer by sputum cytology and transferred to our hospital for operation. The tumor was obscure on palpation during thoractomy, but malignancy could not be ruled out based on analysis of frozen sections. Therefore, a right lower lobectomy and mediastinal lymph node dissection were performed. Pulmonary infarct was not suspected until thrombi were observed in the dissected pulmonary artery. Urokinase and heparin were intravenously administered soon after the operation, but the patient died of pulmonary thromboembolism of the sixth postoperative day. Examination of the operative specimen revealed pulmonary thromboembolism with infarction and no evidence of malignancy. Atypical cells observed in sputum cytology seemed to be derived from basal cell hyperplasia in the area of infarction. Type II alveolar epithelial cell hyperplasia was observed in the periphery of the infarction. These findings seemed to make accurate analysis of frozen sections difficult. An increasing number of cases of pulmonary thromboembolism is being reported in Japan. Therefore, pulmonary infarct with false positive cytology may be encountered more frequently in the future.