LAUSR

Post-transfusion purpura (PTP) is a rare, immune-mediated disorder characterised by severe thrombocytopaenia occurring 5–12 days after a blood transfusion. It occurs in approximately from 1 out of 24 000 to 1 out of 100 000 transfusions. It occurs when the immune system attacks transfused platelets, particularly those with the human platelet antigen-1 a (HPA-1a), which the body recognises as foreign if the person has been previously exposed to it. This antigenic reaction is more likely in individuals with a history of pregnancies or transfusions involving platelets expressing HPA-1a. Patients who has anti-HPA- 1a antibodies after having being exposed to platelets which contains HPA-1a antigens following pregnancy or blood transfusion are at risk of PTP. The management of PTP typically involves transfusing platelets lacking this antigen, immunosuppression, plasmapheresis to remove antibodies and close monitoring. This case report highlights a rare and life-threatening complication of PTP—the first documented occurrence of diffuse alveolar haemorrhage (DAH) in an elderly patient with a remote history of immune thrombocytopaenic purpura. The patient developed respiratory distress, diffuse petechiae and profound thrombocytopaenia 8 days after receiving a blood transfusion for symptomatic chronic anaemia. A comprehensive diagnostic workup, including bronchoscopy, confirmed the presence of DAH. Prompt recognition and management, involving specialised blood products, immunosuppression and close monitoring, led to a successful outcome in this complex clinical scenario. This case underscores the challenges in diagnosing and managing PTP, especially in elderly patients with multiple comorbidities and a history of blood disorders. It highlights the critical importance of swift identification and intervention to prevent life-threatening complications in such patients.