The diagnosis of pulmonary lymphangiosis carcinomatosa (PLC) is of great importance for the prognostically-oriented therapy stratification of tumor patients. In this field, high-resolution computed tomography (HRCT) is the state of the art in imaging. Using HRCT, it is possible to identify pulmonary parenchymal structures in a detailed fashion to evaluate interstitial patterns. This step is preceded by an x-ray of the thorax that detects pathological findings and rules out other diseases. The typical characteristics of PLC are described with particular attention to HR-phenomenology, and discussed in comparison with the literature regarding anatomy and pathogenesis. Finally, conclusions are drawn for differential diagnosis and supported by characteristic cases.