Langerhans cell histiocytosis: coexistence of bronchogenic and thymic cysts in the thymus.

Langerhans cell histiocytosis (LCH) is a disease caused by the proliferation of Langerhans cells in various tissues or organs. A 43-year-old male patient presented with an anterior mediastinal mass in the thymus. Histological examination after a thymectomy revealed a bronchogenic cyst in the thymus, and multiple LCH and small thymic cysts were also incidentally observed in the thymus. Unifocal LCH in an adult occurring in the thymus is extremely rare. Furthermore, no cases of LCH with the coexistence of bronchogenic and thymic cysts in the thymus have been previously reported.