A Rare Case of Mycoplasma Pneumoniae Infection Causing Cold-Agglutinin Autoimmune Hemolytic Anemia

Abstract

SESSION TITLE: Student/Resident Case Report Poster - Chest Infections II SESSION TYPE: Student/Resident Case Report Poster PRESENTED ON: Tuesday, October 25, 2016 at 01:30 PM - 02:30 PM INTRODUCTION: Mycoplasma pneumoniae typically causes upper respiratory infections and atypical pneumonia and hemolysis can be an uncommon extrapulmonary manifestation. We present an unusual case of Mycoplasma pneumoniae pneumonia causing cold-agglutinin autoimmune hemolysis in an immunocompetent patient. CASE PRESENTATION: A 63-year-old Hispanic male with hypertension presented with non-productive cough for two weeks, associated with shortness of breath and fatigue. He was tacchycardic, tacchypneic, saturating 92% on room air, with a temperature of 102.1° Farenheit. Pulmonary exam revealed scattered rhonchi in the right lower lung field and diminished breath sounds in the left base. Laboratory investigations showed leukocytosis. Computed tomography of the chest showed areas of nonspecific groundglass attenuation in the right upper lobe and inferior right middle lobe along with enlarged hilar and subcarinal lymph nodes. IgM titer for Mycoplasma pneumoniae was 5081 units/mL (Ref < 770). Despite treatment with Ceftriaxone and Azithromycin, his hypoxia worsened as he became jaundiced with notable scleral icterus. His hemoglobin level decreased from 13.3 g/dL to 6.6 g/dL. Haptoglobin level was consistently low along with elevations in LDH, total and direct bilirubin. A peripheral blood smear revealed red blood cell agglutination with no evidence of spherocytes. Direct antiglobulin test was 3+ positive for C3d and weakly positive for IgG. Cold-agglutinin antibody titer obtained towards the end of his stay was 1:64, confirming the diagnosis of cold agglutinin autoimmune hemolysis. He finished a 14-day course of Azithromycin, received warmed IV fluids along with strict cold avoidance, leading to an improvement of his symptoms and hemoglobin. Two weeks after discharge, his hemoglobin continued to increase to 12.4g/dL. DISCUSSION: In 50 to 75% of Mycoplasma pneumoniae infections, IgM cold agglutinins are formed against erythrocyte I antigen but only rarely does it lead to hemolysis. The majority of erythrocyte destruction is extravascular as complement coated erythrocytes are phagocytosed by reticuloendothelial cells, especially Kupfer cells in the liver. In this case of autoimmune hemolysis, the patient’s symptoms improved with supportive treatment, cold avoidance, and an extended course of Azithromycin. Severe symptomatic hemolysis can be treated with Rituximab, cytotoxic agents or plasmapheresis. CONCLUSIONS: Mycoplasma pneumoniae is a well recognized cause of pneumonia but its association with cold-agglutin autoimmune hemolysis is rare; very few case reports exist around the world. Early suspicion and detection in the appropriate clinical setting can aid physicians in preventing further erythrocyte destruction in these patients. Reference #1: Han X et al. Mycoplasma pneumonia associated with hemolytic anemia: case report. Chinese J of TB and Resp Diseases. 2011 Nov;34(11):832-6. DISCLOSURE: The following authors have nothing to disclose: Robert Chao, Kayur Shah No Product/Research Disclosure Information