PO157 | DIAGNOSTIC CHALLENGES IN PREGNANCY-TRIGGERED IMMUNE-MEDIATED THROMBOTIC THROMBOCYTOPENIC PURPURA: A CASE FOR EARLY AND ACCURATE IDENTIFICATION

M. Siepi¹, G. Rescigno² | ¹UOC Patologia Clinica, AORN Santobono-Pausilipon, Napoli, Italy; ²UOC Patologia Clinica, AOU San Giovanni di Dio Ruggi d'Aragona, Salerno, Italy

Background. Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare and potentially fatal thrombotic microangiopathy (TMA) characterized by severe ADAMTS13 deficiency due to the presence of inhibitory autoantibodies. iTTP typically presents with the classic pentad of thrombocytopenia, microangiopathic hemolytic anemia, neurological symptoms, renal dysfunction, and fever. However, the clinical presentation can overlap with other pregnancy-related TMAs, such as subset of HELLP syndrome and atypical hemolytic uremic syndrome (aHUS), complicating timely diagnosis. Pregnancy is a known trigger for iTTP, and rapid recognition is crucial to avoid maternal and fetal complications. The PLASMIC score has been validated as an effective tool for early risk stratification, facilitating prompt therapeutic intervention. Early diagnosis and treatment with plasma exchange, immunosuppressive agents, and novel therapies such as caplacizumab are critical for improving outcomes in this life-threatening condition.
Patients and Methods. A 28-year-old woman at 32 weeks of gestation presented with abdominal pain, severe asthenia and acute neurological symptoms. Laboratory evaluation revealed severe microangiopathic hemolytic anemia and thrombocytopenia with hemoglobin 5.1 g/dL (reference range [RR] 12–16), platelet count 40 ×10³/mm³ (RR 150–400), markedly elevated lactate dehydrogenase 2279 U/L (RR 135–250), reticulocytosis 330.9 ×10³/µL (RR 22.0–139.0), indirect hyperbilirubinemia 0.99 mg/dL (RR 0.1–0.9) and undetectable haptoglobin, in the absence of coagulopathy and with mild renal impairment. Due to maternal-fetal deterioration, emergency cesarean section was performed. Peripheral blood smear demonstrated 3% schistocytes. Early clinical probability of severe ADAMTS13 deficiency was assessed using the PLASMIC score. A comprehensive diagnostic work-up excluded secondary TMAs, including autoimmune disorders (ANA, ENA, antiphospholipid antibodies, ANCA, lupus anticoagulant), infections (CMV, EBV, HBV, HCV, HIV, TORCH), malignancy, immune hemolysis (Coombs tests) and active infections (negative microbiological cultures).
Results. The PLASMIC score was 6, indicating high risk of severe ADAMTS13 deficiency. ADAMTS13 activity was undetectable (0%) with detectable inhibitory anti-ADAMTS13 autoantibodies, confirming iTTP. Immediate treatment with therapeutic plasma exchange, high-dose corticosteroids and caplacizumab resulted in rapid neurological recovery and platelet count normalization. Persistently suppressed ADAMTS13 activity prompted early anti-CD20 therapy with rituximab, achieving progressive enzymatic recovery. The patient was discharged in stable condition and scheduled for close hematologic monitoring.
Conclusions. This case underscores the importance of rapid hematologic assessment and early risk stratification in pregnancy-associated TMAs. Integration of PLASMIC score–guided decision-making with prompt initiation of plasma exchange, caplacizumab and immunosuppressive therapy represents the current standard of care for iTTP and is feasible and effective even in the peripartum setting.