SOLITARY PULMONARY NODULE



A solitary pulmonary nodule is defined as a rounded lesion with well-demarcated margins. Between 5 and 40 per cent are malignant. Benign lesions are usually smaller (less than 2 cm), have sharp borders and no satellite lesions, and are present in younger people (less than 40 years). Three characteristics help to separate benign from malignant nodules. Nodules with doubling times of less than 10 to 20 or more than 450 days are most likely benign. The presence of calcification with a central, speckled, diffuse, laminar, or popcorn pattern, but not eccentric calcification is also evidence of its benign nature. On rare oc^ casions the clinical picture is clearly benign e s a patient with a previously normal chest x-ray who develops well-documented histoplasmosis hat resolves leaving a single histoplasmoma. A suggested decision tree for the approach to the solitary nodule is shown in .