Langerhans' cell histiocytosis of the thymus associated with multilocular thymic cyst.

Though Langerhans' cells are a normal component of the thymus, the pathologic entity of Langerhans' cell histiocytosis (LCH) occurs very uncommonly in this organ. The few reports of thymic LCH are nearly all in children or young adults and may or may not be associated with extrathymic clinical disease. Although radiographic descriptions of cyst formation in the thymus in association with LCH have been reported, no examples to our knowledge of thymic LCH have been reported in association with multilocular thymic cyst (MTC). We report a case of thymic LCH in association with an asymptomatic multilocular thymic cyst which was discovered as part of cardiothoracic surgery in a middle-aged man. To our knowledge, this is the first example of MTC occurring in association with thymic LCH. HUM PATHOL 31:1532-1535. Copyright 2000 by W.B. Saunders Company