Case Presentation: A 28-year-old female with a medical history of lupus nephritis, chronic kidney disease (CKD) stage 4, and chronic anemia presented with progressive dyspnea on exertion, easy bruising, and a presyncope episode. She denied any fever, recent illness, diarrhea, vomiting, sick contacts, or changes in medication. On arrival, the patient was hemodynamically stable. Laboratory results showed hemoglobin of 6.7, platelets of 7, a reticulocyte count of 5.4, total bilirubin of 2.7, LDH of 904, haptoglobin < 10, and creatinine of 3.3 (baseline creatinine 2.2-2.5). Chest X-ray and EKG were unremarkable for acute changes. The patient was admitted for acute hemolytic anemia with thrombocytopenia, with concern for thrombotic microangiopathy. A Coombs test was negative, and peripheral blood smear revealed schistocytes. A DIC panel was negative. The patient was treated with intravenous steroids and plasma exchange for five days. Hemolytic parameters normalized, and platelet counts stabilized. ADAMTS13 activity was found to be low, with elevated inhibitor levels. Rituximab therapy and caplacizumab were initiated. The patient's clinical condition improved, and she was subsequently discharged.
Discussion: Immune-mediated thrombocytopenic purpura (iTTP) is a type of microangiopathic hemolytic anemia (MAHA), which is rare and potentially life-threatening. It occurs due to a decrease in ADAMTS13 levels (1). The occurrence of iTTP in systemic lupus erythematosus (SLE) is a very rare complication, affecting fewer than 0.5% of individuals (2). SLE and iTTP often have overlapping features, such as hemolytic anemia, thrombocytopenia, and neurological and respiratory symptoms, as was observed in our patient. However, the severely low platelet count, combined with ongoing evidence of Coombs-negative hemolytic anemia, raised suspicion of a more severe underlying condition. TTP was at the top of our differential diagnosis, despite the lack of a classic initial presentation, prompting swift initiation of plasmapheresis and steroid therapy. Other differentials considered included complement-mediated HUS and CAPS; however, ADAMTS13 levels and inhibitor testing confirmed our diagnosis.
Conclusions: Diagnosing iTTP in patients with SLE can be challenging due to overlapping clinical presentations. However, the presence of a low platelet count along with Coombs-negative hemolytic anemia should increase clinical suspicion for iTTP and support early consideration of plasmapheresis and steroid therapy.