Study of Sequential Administration of Oral 6-Thioguanine After Methotrexate in Patients With LCH

Inclusion Criteria: * Patients with histologic proof of LCH who have multifocal or multisystem disease involvement. * Patients must have a life expectancy of at least 8 weeks. * All patients must have ECOG performance level rating of-\< 2. * Patients or their parents (guardian) must sign an informed consent indicating that they are aware of the investigational nature of the study, using commercially available drugs. * Patients must have recovered from the toxic effects of prior therapy before entering this study or at least 2 weeks should have elapsed since the end of last course of chemotherapy. * Patients must have adequate liver function (bilirubin \_\< 2.0 mg/dl, SGOT less than 1.5 times normal (unless it is due to disease), adequate renal function (creatinine \<\_ 1.5 mg/dl, creatinine clearance \>\_ 60 ml/min/1.73 m2) and normal electrolytes. * Patients should have a granulocyte count \> 500/uL and a platelet count \>\_ 100,000/uL (unless due to disease involvement of the bone marrow). * Male and female patients of child-bearing age should use effective methods of contraception, if sexually active. Exclusion Criteria: * Patients with active infections or significant medical conditions other than their disease (LCH) shall be excluded.