Solitary cirumscribed density - nodule (<3 cm) or mass (3 or more cm)
Find old CXR for comparison. If available compare with date and determine tumor doubling time (measures volume). If doubling time is <1 mo - >480 days, it is likely to be benign. If doubling time is >1 mo - 480 days, it is likely to be malignant.
If there is no CXR for comparison, risk stratify based on age and risk factors
Pt. <35 yrs, <2 cm, smooth contours, no smoking, benign calcification appearance (pop-corn or bull's eye type) = low risk > f/up HRCT at 3, 6, 9, 12, and 24 mo x 2 years. If no change. STOP. If lesion doubled > open lung bx.
Pt. >50 yrs, >2 cm, irregular, spiculated, corona radiata like borders; no calcificaiton, smoker = high risk > open lung bx.
Causes:
Malignant: lung Ca, carcinoid, metastases, sarcoma
Benign: hamartoma, TB, histoplasmosis, fibroma, abscess, lipoma, rheumatoid nodule, infarct, bronchogenic cyst, and AVM.