Imaging description

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare interstitial lung disease that primarily affects young adult smokers. PLCH begins as densely cellular, peribronchiolar nodules and has a characteristic predilection for the upper lungs. Treatment is cessation of smoking and corticosteroids in selected patients. In PLCH, CT classically shows a combination of nodules and cysts in the mid and upper lungs with sparing of the lung bases. PET scans show irregular, increased pulmonary activity corresponding to the nodular disease on CT (Figure 78.1). PLCH patients with a dominant cystic pattern and fewer nodules demonstrate less pulmonary FDG uptake [1–3].

Importance

The presenting symptoms of PLCH are very nonspecific, but the CT imaging findings are usually diagnostic. The presence of significant FDG uptake corresponds to a considerable inflammatory component to the disease and provides support for treatment with corticosteroids in addition to smoking cessation.