: Langerhans cell histiocytosis (LCH) is a well-known neoplastic disorder of Langerhans cells which has characteristic findings, however, LCH has not been adequately studied in Korea. Methods : We analyzed the clinicopathologic features of 20 patients with LCH who were diagnosed between 1997 and 2006 at the Korea University Guro and Anam Hospitals. Results : The M:F ratio was 3:1 and the age ranged from 2-60 years (mean, 23.8 years [4 in 1st decade, 6 in 2nd decade, 2 in 3rd decade, 5 in 4th

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... ade and 3≥40 years of age). The cases were classified as unifocal unisystemic in 13 patients, multifocal unisystemic in 4 patients, and multifocal multisystemic in 3 patients. The bone was the most commonly involved organ (14), followed by lymph node (5), lung (2), skin (2) and ureter (1). The Langerhans cells were immunohistochemically stained with Langerin, CD1a, S-100 protein, and CD68. Langerin and CD1a were specific for Langerhans cells. Conclusions : The distribution of the involved organs in patients with LCH was similar to the distribution in Western countries, but lymph node involvement was more frequent, whereas lung involvement was less common. Langerin is considered to be a specific marker for Langerhans cells.