Differentiation of Benign and Malignant Solitary Pulmonary Nodule: Literature Review

The solitary pulmonary nodule (SPN) is frequently seen on chest radiographs and computed tomography (CT), usually the identification is accidental. The overall prevalence of malignancy is relatively low but identification of malignancy of nodule is of prime importance. There are different characters of nodules indicating malignancy, and also the exposure of person to risk factors increases the chances of malignancy of nodule. Chances of malignancy rise with increasing size, the irregular, lobulated border of the nodules is highly associated with higher probability of malignancy and nodules with pure ground grass appearance have higher probability of malignancy, irregularly marginated nodule displaying a corona radiata sign indicating neoplastic infiltration with distortion of neighbouring tissue is almost certainly a malignant nodule. Stippled, punctuate, and eccentric calcifications are suggestive of malignancy. There are 20% - 75% of chances of malignancy if nodule is appeared with ground-glass opacity. Malignant nodules have higher growth rate as compared with benign nodules, malignant nodules usually have doubling time (DT) of 30 - 400 days while DT of more than 450 days is sign of benignity whereas doubling time less than 30 days is usually acute infectious process. The presence of fat within nodule is sign of benignity. Increasing density of the nodule is suggestive of malignancy and requires shorter follow up. Besides the nodule evaluation the chances of malignancy can also be evaluated through the exposure of patient to risk factors like age, current and past smoking status and history of extra thoracic malignancy. The management depends upon various factors mainly three strategies are applied for management including careful observation of nodule, use of diagnostic techniques like CT FNA, PET, and broncoscopy and surgery.