[Hypercalcemia complicating Waldenström's disease: a manifestation of Richter's syndrome]

Acute hypercalcemia occurred during the following-up of a 70 years old man with Waldenström's Macroglobulinemia (WM). Hematological data were still unchanged in spite of stopping treatment 16 months ago. It is an unusual complication in chronic lymphoproliferative disorders (except, multiple myeloma) and it was never described in the course of WM. It was related to the emergence of diffuse immunoblastic lymphoma, as it has been termed Richter syndrome in chronic lymphocytic leukemias. In WM, this occurrence is less known, but symptoms and prognostic are similar. It is to be pointed out that the spontaneous decrease of the amount of monoclonal IgM is an ominous sign of this immunoblastic transformation. The pathogenesis of hypercalcemia is discussed: the eventuality of a tumoral osteoclast activating factor is suggested.