Methotrexate and Cytosine in Adult Langerhans Cell Histiocytosis

Inclusion Criteria: 1.DISEASE CHARACTERISTICS: * Histopathologically confirmed diagnosis of Langerhans cell histiocytosis according to the criteria defined by the Histiocyte Society * Demonstration of CD1a antigenic determinants on the surface of lesional cells (by immunocytology or immunohistology) or Birbeck granules in lesional cells by electron microscopy * Considered at risk or low risk according to the following criteria: * Multi-system at risk disease, defined as involvement of one or more risk organs (i.e., hematopoietic system, liver, spleen, or lungs) 1.No single-system lung involvement * Multi-system low-risk disease 1.Multiple organs involved but without involvement of risk organs * Single-system disease 1.Multifocal bone disease (i.e., lesions in 2 or more different bones) 2.Localized special site involvement, such as CNS-risk lesions with intracranial soft tissue extension or vertebral lesions with intraspinal soft tissue extension 3.Vault lesions are not regarded as CNS-risk lesions 2.PATIENT CHARACTERISTICS: 1. Not pregnant or nursing 2. Negative pregnancy test 3. Fertile patients must use effective contraception 3.PRIOR CONCURRENT THERAPY: <!-- --> 1. No prior treatment for Langerhans cell histiocytosis Exclusion Criteria: