Improvement of Erdheim-Chester disease in two patients by sequential treatment with vinblastine and mycophenolate mofetil.

Erdheim-Chester disease (ECD) is a rare non-Langerhans' form of histiocytosis with a plethora of different clinical manifestations owing to multiple organ involvement. We report two patients who presented initially with different clinical symptoms. The presenting complaint of the first patient was bone pain, predominantly in the legs, whereas in the other patient the initial symptoms were related to obstruction of both ureters, as in idiopathic retroperitoneal fibrosis. Ultimately, ECD was diagnosed in both patients by the occurrence of both pathognomonic manifestations, the histologic presence of non-Langerhans' histiocytes in bone biopsies, and osteosclerotic lesions of the long bones. Because the extraosseous manifestations progressed and a single application of corticosteroids was ineffective, sequential treatment with vinblastine and mycophenolate mofetil, together with prednisolone, was started. At follow-up respectively 15 and 16 months after the start of treatment a beneficial effect was noted in both patients. These cases illustrate the clinical spectrum of ECD, detail the pathognomonic manifestations of this rare disease, emphasize the need to consider ECD as an uncommon but important differential diagnosis in patients with arthralgias or systemic fibrosis, and give the first evidence for a new treatment option.