Variability in the efficacy of interferon-alpha in Erdheim-Chester disease by patient and site of involvement: results in eight patients.

OBJECTIVE: Erdheim-Chester disease (ECD) is a rare, non-Langerhans form of histiocytosis of unknown origin, characterized by infiltration of tissues by spumous histiocytes. ECD features heterogeneous systemic manifestations, and the general prognosis remains poor despite various treatment options. METHODS: We treated 8 patients with multisystemic ECD with subcutaneous interferon-alpha (IFNalpha) at a dosage of 3-9 x 10(6) units 3 times weekly, for a median duration of 23 months (range 1-46 months). RESULTS: Treatment was generally well tolerated, and side effects remained limited to fever following injections. Treatment was discontinued in 1 patient, because of severe depression. During treatment, some manifestations of ECD disappeared (i.e., xanthelasma, exophthalmos, papilledema, and intracranial hypertension). The efficacy of IFNalpha on cardiovascular ECD was variable, however. Treatment resulted in partial regression of "coated aorta" in some cases and clear failure in others; 2 patients died. The level of C-reactive protein diminished sharply in 5 patients. CONCLUSION: IFNalpha might be a valuable first-line therapy for prolonged treatment of ECD. However, the efficacy of IFNalpha varies among patients and according to the sites of disease involvement, and symptoms may fail to respond to treatment, especially in patients with severe multisystemic forms of ECD with central nervous system and cardiovascular involvement.