Pulmonary Langerhans Cell Histiocytosis (PLCH) Imaging

In young smokers (20s-30s), PLCH follows a unique "nodule-to-cyst" evolution. It begins as centrilobular nodules in the upper lobes that eventually cavitate into thick, then thin-walled cysts.

• The Hallmark: "Bizarre-shaped" cysts, created when multiple cysts merge into complex geometries.

• The Landmark: It strictly spares the costophrenic angles, targeting the "penthouse" (upper lobes) while leaving the "basement" clear.

• The Recovery: Spontaneous resolution is common, but typically requires immediate smoking cessation.