Erdheim-Chester disease

Imaging description Erdheim-Chester disease is a very rare interstitial lung disease characterized by infiltration of non-Langerhans cell histiocytes or macrophages forming granulomatous lesions with fibrosis. The bones are the primary site of involvement (osteosclerotic lesions) (Figures 17.1 and 17.2), but pulmonary involvement can occur. The infiltration occurs most prominently along the lymphatics, and therefore affects the interlobular septa, bronchovascular bundles, and visceral pleura. On high-resolution CT chest, the major findings are smooth thickening of the fissures and interlobular septa, ground-glass opacities, and centrilobular nodules, which are slightly more prominent in the mid and upper lungs (Figures 17.1–17.3) [1–3]. Pleural effusions are present in roughly 50% of cases (Figure 17.1). Other common findings include pericardial thickening or effusion and extrathoracic soft tissue masses. The extrathoracic soft tissue is often seen surrounding the kidneys and in the retroperitoneum (Figures 17.2 and 17.3) [2].