[Acquired von Willebrand's disease].

We describe a patient with acquired von Willebrand's disease and Waldenström's macroglobulinemia. He suffered from an acquired tendency to bleed. The laboratory findings were identical to those of congenital von Willebrand's disease. The acquired form of this bleeding disorder is seen in association with immunologically active B cell lymphomas, certain other malignant tumours, and autoimmune diseases. The incidence and prevalence are unknown, but this disorder is probably uncommon. We discuss possible pathogenetic mechanisms. Acquired von Willebrand's disease should be considered in patients with an acquired tendency to bleed, especially if the patient also has a lymphoproliferative, neoplastic, or autoimmune disease.