Leukocytoclastic (small vessel) vasculitis in multiple myeloma.

The hallmark of leukocytoclastic vasculitis (LCV) is palpable purpura. Histologically, there is a neutrophilic, angiocentric, segmental inflammation with endothelial cell injury and fibrinoid necrosis of the blood vessel walls. Leukocytoclastic vasculitis has many associations, including, rarely, multiple myeloma (MM). A total of 2357 patients with a diagnosis of MM were reviewed to retrieve cases that had developed leukocytoclastic vasculitis. Eight patients with MM and LCV showed a predominance of immunoglobulin G (IgG) myeloma paralleling the immunoglobulin secretion seen overall. Overexpression of interleukin 6, which is necessary for myeloma cell growth and survival, may contribute to the pathogenesis of LCV in the setting of MM.