| Discussion: Lymphangitis carcinomatosis is usually the result of hematogenous metastases to small pulmonary capillaries, with secondary invasion of peripheral pulmonary lymphatics. Retrograde extension from hilar or mediastinal nodes or direct invasion from diaphragmatic lymphatics is less common. Breast, lung, stomach, pancreas, and prostate cancers are the most common tumors that result in lymphangitis. Endobronchial metastases are rare, and they are associated with tumors of the breast, colon, and kidney, as well as sarcoma and melanoma.
CT findings: irregular, nodular, and/or smooth interlobular septal thickening; thickening of the fissures due to involvement of the lymphatics concentrated in the subpleural interstitium; preservation of normal parenchymal architecture at the level of the secondary pulmonary lobule; peribronchovascular thickening; centrilobular peribronchovascular thickening, which predominates over interlobular septal thickening in a minority of patients; polygonal arcades or polygons with prominence of the centrilobular bronchovascular bundle in association with interlobular septal thickening (50%); mediastinal and/or hilar lymphadenopathy (30-50%); and pleural effusions (30-50%).
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LYMPHANGITIS CARCINOMATOSIS 
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