Severe thrombophilia with antiphospholipid syndrome and hyperhomocysteinemia in a patient with Schnitzler's syndrome.

Schnitzler's syndrome is a rare condition with chronic urticaria, intermittent fever, bone pain, and a monoclonal IgM gammopathy. Most patients have a chronic and indolent course, but a small number ultimately progress to a lymphoplasmacytic malignancy. We describe a patient with Schnitzler's syndrome who entered an accelerated phase of clinical deterioration with repeated thromboses of the cerebral and coronary arteries that ultimately led to a fatal outcome. We found that the he fulfilled the Sapporo criteria for definite antiphospholipid syndrome and had elevated blood levels of homocysteine during the active clotting phase of the disease. We suggest that the association with immune-mediated or metabolic disorders, such as the antiphospholipid syndrome and hyperhomocysteinemia, may unfavorably affect the otherwise chronic and stable course of patients with Schnitzler's syndrome. The systemic clotting disorder, the association with the antiphospholipid syndrome and hyperhomocysteinemia, and the biclonal rather than monoclonal IgM gammopathy were striking features of this atypical case of Schnitzler's syndrome.