Septal thickening Thickening of the lung interstitium by fluid, fibrous tissue, or infiltration by cells results in a pattern of reticular opacities due to thickening of the interlobular septa. Although thickening of the interlobular septa is relatively common in patients with interstitial lung disease, it is uncommon as a predominant finding and has a limited differential diagnosis (Table). Smooth septal thickening is usually seen in interstitial pulmonary edema (Kerley B lines on chest film); lymphangitic spread of carcinoma or lymphoma and alveolar proteinosis. Nodular or irregular septal thickening occurs in lymphangitic spread of carcinoma or lymphoma; sarcoidosis and silicosis. #Diagnosis #Radiology #Pulmonary #HRCT #CTChest #Reticular #SeptalThickening #Differential #RadiologyAssistant
