Pulmonary Langerhans cell histiocytosis

Imaging description The classic CT appearance of pulmonary Langerhans cell histiocytosis (PLCH) is a combination of cysts and small nodules [1, 2]. Cysts are the most common finding and nodules are almost always seen in conjunction with cysts. The cysts spare the lung bases (Figures 12.1–12.4) and frequently demonstrate irregular shapes. Cyst walls can range from relatively thick to barely perceptible. The pulmonary nodules are typically 1–5 mm in diameter and also spare the bases. Nodules are typically more numerous in the early stages of the disease (Figure 12.1) while cysts predominate in later stages (Figures 12.2–12.4). Importance The diagnosis of PLCH can typically be made solely on the basis of the CT findings. Smoking cessation can result in resolution of the disease.