Pilot Study of Tocilizumab in Patients With Erdheim-Chester Disease

Inclusion Criteria: * patients \>= 18 years of age able to understand and sign an informed consent; * histologically proven diagnosis of Erdheim-Chester disease ; * an advanced disease not limited to the skeleton, with at least one measurable lesion; * if females of childbearing potential, a negative pregnancy test and willingness to adhere to a highly effective contraceptive method of birth control for the duration of the study; Exclusion Criteria: * history of hypersensitivity to tocilizumab or to any of the excipients; - severe infections requiring hospitalization or antibiotic therapy in the 30 days before the enrollment in the study; * active tuberculosis, listeriosis, histoplasmosis, sepsis, abscesses, opportunistic infections; active hepatitis B or C virus infection; * past history of tuberculosis (as documented by a positive purified protein derivative (PPD) skin test and/or a positive Quantiferon test and/or a chest X- ray), in the absence of a documented and appropriate administration of a specific treatment for latent tuberculosis; * history of human immunodeficiency virus (HIV) infection; * past history (\< 5 years before enrollment) of a lymphoproliferative disorder or of a solid cancer (excluding cured basal cell or squamous cell carcinoma of the skin); * moderate or severe heart failure (NYHA class III/IV), uncontrolled diabetes mellitus or other diseases that -according to the physician in charge of the protocol- may be of harm to the patient, if he/she would enroll in the study; * history of alcohol and/or drug abuse; * prior treatment with alkylating drugs (chlorambucil, cyclophosphamide); * serum creatinine \> 1.6 mg/dL in female patients or \> 1.9 mg/dL in male patients, aspartate aminotransferase and/or alanine aminotransferase \> 3 x upper limit of normal ; platelet \< 100.000/fL; hemoglobin \< 8.5 g/dL; white blood cell count \< 1000/fL; lymphocyte \< 500/fL; total bilirubin \> 2.0 mg/dL