Erdheim-Chester disease (ECD) is a very rare and aggressive form of non-Langerhans histiocytosis with unclear pathogenesis. Because of the heterogeneity of clinical presentation, diagnosis is often challenging and delayed. Currently, Interferon alpha is the first line treatment that is associated with a better survival. The prognosis is relatively poor, especially in case of neurological and cardiovascular involvement. Herein, we report the case of a 64-year-old Tunisian female patient presenting an aggressive form of ECD revealed by diabetes insipidus and cerebellar ataxia with a diagnosis delay of 4 years. The assessment of disease extent had also shown associated asymptomatic cardiac and bone involvement. Pegylated Interferon alpha was started at high dose allowing disease stabilization. This case illustrates that physicians should be aware of the heterogeneous manifestations of ECD in order to insure an early diagnosis and treatment. Long-term and regular follow-up is crucial because of the risk of disease progression.