[Sjögren's syndrome combined with cold agglutinin disease: A case report].

Sjögren's syndrome(SS)is a chronic autoimmune disease that affects exocrine glands, especially salivary and lacrimal glands. The main clinical manifestations are dry mouth and dry eyes, but also multi-organ and multi-system can be involved. Cold agglutinin disease(CAD)is an autoimmune disease characterized by red blood cell agglutination in the blood vessels of extremities caused by cold agglutinin at low temperature, resulting in skin microcirculation disturbance, or hemolytic anemia. Cold agglutinin disease is divided into two categories, primary cold agglutinin disease and secondary cold agglutinin disease. Primary cold agglutinin disease is characterized with cold agglutinin titer of 1 ∶4 000 or more and positive Coomb's test. However, the Coomb's test is not necessarily positive and the cold agglutinin titer is between 1 ∶32 and 1 ∶4 000 in secondary cold agglutinin disease. Here, we reported an elderly patient admitted to hospital due to fever. He was diagnosed with respiratory infection, but he showed incompletely response to the anti-infection treatment. Further laboratory tests showed the patient with positive ANA and anti-SSA antibodies. Additionally, the patient complained that he had dry mouth and dry eyes for 1 year. Schirmer test and salivate gland imaging finally confirmed the diagnosis Sjogren's syndrome. During the hospital stay, the blood clots were found in the anticoagulant tubes. Hemolytic anemia was considered as the patient had anemia with elevated reticulocytes and indirect bilirubin. In addition, further examination showed positive cold agglutination test with a titer of 1 ∶1 024, and cold agglutinin disease was an important type of cold-resistant autoimmune hemolytic anemia. Furthermore, the patient developed cyanosis after ice incubating at the tip of the nose. Hence, the patient was diagnosed as CAD and he was successfully treated with glucocorticoids instead of anti-infection treatments. Hence, the patient was diagnosed with SS combined with secondary CAD. SS combined CAD are rarely reported, and they are both autoimmune diseases. The abnormal function of B lymphocytes and the production of autoantibodies might be the common pathogenesis of them. Cold agglutinin disease can lead to severe hemolytic anemia, even life-threatening. In clinical practice, timely recognizing and dealing with CAD might promote the prognosis of the patient.