A case of cold agglutinin disease in the course of treatment for polymyalgia rheumatica.

A 60-year-old male who had been treated for polymyalgia rheumatica (PMR) with Raynaud's phenomenon was admitted to our hospital with acrocyanosis and rapid progressive anemia. Hemolytic anemia with reduction of haptoglobin and cold agglutinin was detected, and the patient had a negative Donath-Landsteiner test. A skin biopsy from his toe revealed microthromboembolism without vasculitis, resulting in the diagnosis of cold agglutinin disease (CAD). This is a first case report of CAD complicated with PMR.