[A case of well-differentiated nonmucinous adenocarcinoma of the lung with an 18-year clinical course before surgery].

A 56-year-old woman was referred for an abnormally dense area in the right upper lung field detected at medical checkup. This shadow had been pointed out frequently since she was 38 years old, but no pathological diagnosis of lung cancer had been given. The size of the abnormal area had gradually increased over the 18 years. Since lung cancer was suspected on the basis of the radiographic findings, she underwent open lung biopsy. Pathologically, the tumor tissue showed a lepidic growth pattern on the wall of preexisting alveoli; and formation of fibrotic foci caused by the collapse of alveoli and the microscopic destruction of the elastic fiber framework were seen in the tumor. There was no vascular invasion or lymphatic infiltration in the tumor. It was diagnosed as well-differentiated nonmucinous adenocarcinoma, p-T2 N0 M0. Although this tumor was untreated for 18 years from the first detection using chest radiography, the critical invasive features were not in evidence pathologically.