A Sticky Situation: Diagnosing Post-Transfusion Purpura in the Setting of Longstanding, Transfusion-Dependent AML
Authors: Kanakis Constantine E , Donahue Nolan , Krum Kristen 
Published: December 2023

Background
Post-transfusion purpura (PTP), a commonly underreported adverse transfusion event. It is defined as severe thrombocytopenia with related sequelae occurring 5-10 days of transfusion where both transfused and autologous platelets are destroyed. Low cell counts may be masked by other conditions (i.e. AML) and there is a paucity of literature on cases of PTP especially in concurrent pancytopenia. Swift diagnosis is critical for management. This case presents a unique opportunity to examine PTP in a patient with a complex hematopathologic malignancy history.
Methods
Relevant clinical data was obtained through examination of available medical records, concurrent ancillary diagnostic testing, and serological send-out testing was performed. Appropriate investigation and evaluation of repeated transfusion reactions with clinical symptomatology in accordance with available bio-vigilance surveillance guidelines aided in the diagnosis.
Findings
A 73-year-old female patient presented to the emergency department with acute, worsening fatigue, lethargy, pallor, and shortness of breath. She was found at home by emergency medical services with bright red blood covering her legs, originating from the rectum, several longstanding pressure ulcers, and an oxygen saturation in the 80s. The initial physical exam revealed a cachectic, ill-appearing woman who was tachypneic, wheezing, with new and old blood at anus, generalized weakness, fatigue, shortness of breath, cough, myalgias, and diffuse bruising of various sizes. There was no loss of consciousness or history of anticoagulant therapy. The patient had a complex medical history which included acute myeloid leukemia with concurrent chemotherapy complicated by longstanding, transfusion-dependent pancytopenia, lung adenocarcinoma status-post radiation therapy now in remission, congestive heart failure, chronic obstructive pulmonary disease on continuous home oxygen, chronic intermittent bilateral lower extremity rashes secondary to adult-onset Still's disease, and multiple visits to the emergency department, inpatient admissions, and numerous outpatient infusions for the management of pancytopenia.
The patient's initial laboratory workup in the emergency room setting demonstrated clear, previously known, pancytopenia along with severe acidosis, marked anemia, and derangements of coagulation testing. With numerous visits to both the emergency department and outpatient infusion centers, the patient had previous transfusion reactions which ranged from mild allergic to repeating patterns of fulminant weakness, lethargy, and confusion relating to the timing of transfusions. With increasing skin manifestations of purpuric skin lesions, severely acute thrombocytopenia regardless of HLA matched or compatible platelet units, and results of send-out serology demonstrating 100% reactivity to all platelets and specific HPA antibodies, the diagnosis of post-transfusion purpura was made.
Conclusion
Despite this patient succumbing to diffuse hypoxic anemia and suffering a fatal cardiac dysrhythmia, the results of reference laboratory send-out serology revealed positivity in 100% of platelets crossmatched and the presence of antibodies to HLA Class I and HPA-2b, which satisfy the clinical and serologic criteria for post-transfusion purpura and represent a rare diagnostic finding.