Solitary plasmacytoma in the setting of Langerhans cell histiocytosis.

Langerhans cell histiocytosis (LCH) is an intriguing disorder characterized by the accumulation of specialized dendritic cells called Langerhans cells in several diverse tissues and body sites. It has been cited in numerous case reports to be associated with a wide variety of malignant neoplasms. Although many hypotheses have been suggested, the basis for such associations remains essentially unknown. We describe another association here that to our knowledge has not been reported thus far: a solitary plasmacytoma occurring at a site of previous involvement by LCH. This constitutes a new addition to the now fairly lengthy list of malignant neoplasms that have been reported to occur in the setting of LCH. The possible reasons for such an association are discussed along with a brief review of LCH.