POSTTRANSFUSION PURPURA: A RARE ENTITY

Abstract

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Post-transfusion purpura (PTP) is a rare disease characterized by life-threatening thrombocytopenia after transfusion of any platelet-containing blood products, such as platelets(PLT) or packed red blood cells (PRBCs). We report an interesting case of PTP in a young lady after receiving multiple blood products. CASE PRESENTATION: A 36-year-old female with a past medical history of diabetes mellitus and left-sided below-knee amputation (BKA) was admitted to the Intensive Care Unit (ICU) for emphysematous osteomyelitis with intraosseous gas in the calcaneus, cuboid, and fifth metatarsal base of the right lower extremity. She underwent right-sided BKA, requiring multiple PRBC transfusions due to a combination of blood loss during surgery and chronic anemia. The initial platelet count was normal at 329,000/uL. Five days after the PRBC transfusion, it trended down to 17,000/uL and there was concurrent development of a purpuric rash over both arms. Bloodwork was notable for elevated prothrombin time and activated partial thromboplastin time. Hemolysis workup and Coombs test were negative. Fibrinogen was elevated, ruling out disseminated intravascular coagulation. PTP was suspected based on the clinical presentation and exclusion of other etiologies. Anti-human platelet antigen-1a (HPA-1a) antibodies were obtained. Empiric treatment with intravenous immunoglobulin (IVIG) and steroids was promptly initiated. Platelet count improved to 157,000/uL after four doses of IVIG. The patient tested positive for HPA-1a. However, due to the urgent need for treatment, the test sample for the anti-platelet antibodies was drawn after the initiation of IVIG. The development of thrombocytopenia in the classic time frame with the characteristic rash and improvement after receiving IVIG make PTP the most likely diagnosis. She was recommended to receive only washed PRBCs in the future to prevent a recurrence. DISCUSSION: PTP is a rare, underdiagnosed, and potentially fatal reaction, with the development of severe thrombocytopenia 2-14 days after transfusion of platelet-containing blood products. It is considered to be caused by alloimmunization against platelet antigens, with HPA-1a being the most common antibody1. Some cases of HPA-1b mediated PTP have been reported as well2. Diagnosis is often subtle and challenging, therefore a strong clinical suspicion is needed. A history of blood product transfusion a few days before the development of thrombocytopenia should make the physician think about the possibility of PTP. Treatment includes IVIG, steroids, or plasmapheresis3, and initiation of treatment should not wait for diagnostic confirmation. CONCLUSIONS: Clinicians should have high clinical suspicion for PTP in patients with acute, severe thrombocytopenia which develops after blood transfusions, and treatment should be initiated early to favorably alter the course of the disease. REFERENCE #1: Post-transfusion purpura. Kaplan C. Transfus Altern Transfus Med. 2002;4:26–28. REFERENCE #2: Anti-HPA-1b mediated posttransfusion purpura: a case report. Arewa OP, Nahirniak S, Clarke G. Case Rep Med. 2013;2013:3. REFERENCE #3: High-dose IgG for post-transfusion purpura-revisited. Mueller-Eckhardt C, Kiefel V. Blut. 1988;57:163–167. DISCLOSURES: No relevant relationships by Keerthy Joseph, source=Web Response No relevant relationships by SANA MULLA, source=Web Response No relevant relationships by Ruqqiya Mustaqeem, source=Web Response No relevant relationships by Jayamohan Nair, source=Web Response No relevant relationships by Vihitha Thota, source=Web Response