[Clinical evaluation of the small solitary pulmonary nodule]

The diagnostic process for small solitary pulmonary nodules was retrospectively analyzed. Three hundred and forty-three patients, each with a solitary pulmonary lesion of less than 3 cm on chest radiography, were evaluated. The patients were seen at our hospital between September 1986 and December 1993. They consisted of 138 with malignant diseases (114 with lung cancer and 24 with metastatic tumors), and 205 with benign diseases. There were 146 patients (71%) with benign lesions of less than 2 cm. The diagnosis in 118 patients (86%) with malignant disease was made by lung biopsy. Of these 118 patients, 19 underwent biopsy of the lung through a thoracoscope or open lung biopsy via a thoracotomy. Benign diseases were diagnosed in 167 patients (81%) by various laboratory tests and imaging techniques, including chest radiography. Thinsection CT was done in 132 patients. In 72 of these 132 patients (16 with lung cancer, 23 with metastatic tumors, and 33 with benign tumors), a judgement regarding whether the lesion was malignant or not could not be made. Therefore, open lung biopsy was done in 5 patients. Twenty-four patients were only observed, 43 underwent biopsy, and 35 underwent surgery. A decision tree needs to be established to select therapeutic options for management of patients whose diagnoses remain indeterminate even after thin-section CT. Formulation of a decision tree based not only on clinical findings but also on the results of diagnostic imaging is necessary to improve clinical decision making regarding small solitary pulmonary nodules.