Lymphomatous neuropathy in cold agglutinin disease.

Cold agglutinin disease (CAD) is characterized by the production of cold agglutinins (CAs), usually IgMk autoantibodies, causing chronic hemolytic anemia and cold induced acrocyanosis (reported in 90% of cases). CAD has traditionally been classified into a primary type (pCAD) and a secondary type accompanied by malignant disease, most often lymphoma. PCAD is considered a stable or slowly progressive disease with good prognosis (median survival: 12.5 years from onset). It has recently been shown that even pCAD frequently associates with an underlying lymphoproliferative disorder characterized by clonal expansion of B cells.1 Peripheral neuropathy (PN) is a rare complication of CAD, with isolated cases reported, but the pathogenetic mechanisms are still object of debate.2–4 ### Case report. A 58-year-old man was admitted to the hospital because of asymmetric motor and sensory impairment of limbs. Three years before he had developed cold-induced acrocyanosis and pCAD had been diagnosed. At that time, two bone marrow biopsies showed no evidence of lymphoma or plasma cell dyscrasia. Six months before admission, the patient developed progressive weakness, sensory loss, and paresthesias in the right foot; 3 months later, the same symptoms appeared in the left foot and the right hand. On admission, neurologic examination showed asymmetric (right>left) weakness in distal muscles of lower limbs and in the right hand, sensory loss with the same distribution, absent tendon reflexes at lower limbs, and hyporeflexia in the arms. Laboratory investigations showed mild anemia (hemoglobin 10 g/dL), …