Cutaneous necrosis by cold agglutinins associated with glomeruloid reactive angioendotheliomatosis.

The cold agglutinin syndrome is a haemolytic disorder that can cause skin lesions, mainly on the acral areas, with acrocyanosis being the most frequent manifestation. Cutaneous necrosis due to cold agglutinins is very rare. Reactive angioendotheliomatosis (RAE) is an uncommon condition that exclusively affects the skin, characterized by a hyperplasia of endothelial cells and pericytes that can result in the formation of glomeruloid structures. The association of cold agglutinin syndrome with glomeruloid RAE has not been previously described. We report a 70-year-old man diagnosed as having a B-cell low-grade non-Hodgkin's lymphoma. He had two episodes of cutaneous necrosis in acral areas which were related to exposure to cold and due to IgM anti-I(T) cold agglutinins. Biopsy specimens showed vessel proliferations composed of dilated vascular spaces in the dermis and subcutis. Some vessel lumina were partially occluded by eosinophilic thrombi of fibrin and erythrocytes. Numerous closely packed capillaries were observed within pre-existing dilated vessels. This intravascular proliferation of capillaries displayed a glomeruloid pattern. We emphasize the possible presence of a cold agglutinin syndrome in patients with skin necrosis and findings of RAE with a glomeruloid pattern. Cold agglutinaemia may cause these distinctive histological changes.