A Clever Stroke Mimic: Thrombotic Thrombocytopenic Purpura Without Schistocytes - A Case Report and Literature Review.

Background: Thrombotic thrombocytopenic purpura (TTP) is a life-threatening hematologic emergency caused by ADAMTS13 deficiency, leading to microvascular thrombosis, haemolytic anaemia, thrombocytopenia, and end-organ damage. Neurological symptoms occur in up to 90% of cases and are frequently misdiagnosed as stroke. Prompt recognition and treatment reduce the mortality rate from over 90% to 10-20%.

Case presentation: A 70-year-old woman with no significant medical history presented with acute aphasia and right-sided facial and upper extremity numbness. Five days prior, she had experienced fatigue, headache, and bruising. On admission, she had stable vitals with mild aphasia and purpuric ecchymoses noted on examination. Laboratory findings revealed haemolytic anaemia (haemoglobin 7.8 g/dl, lactate dehydrogenase 875 U/l, total bilirubin 2.4 mg/dl), thrombocytopenia (35 ×10⁹/l), and unremarkable coagulation studies (partial thromboplastin time 30 sec, prothrombin time-international normalized ratio 1, fibrinogen 370 mg/dl, D-dimer 2.15 ng/ml). Peripheral smear showed no schistocytes but noted 2+spherocytes. Stroke was ruled out with brain magnetic resonance imaging/magnetic resonance angiography. Given the bicytopenia with possible haemolysis along with new neurological symptoms, TTP was considered in the differential diagnosis. A PLASMIC score of 5 suggested a high probability of TTP. Plasma exchange and corticosteroids were initiated within 5 hours of presentation. ADAMTS13 activity <1% confirmed the diagnosis 4 days after presentation. After five plasma exchange sessions, the patient's platelet count normalized and neurologic deficits resolved by discharge.

Conclusion: This case underscores the importance of considering TTP in stroke mimics, even in the absence of schistocytes, if clinical suspicion is high. Early recognition and initiation of treatment significantly improve patient outcomes.

Learning points: Start plasmapheresis and high-dose steroids immediately for suspected thrombotic thrombocytopenic purpura (TTP), even if schistocytes are absent when clinical suspicions are high.Recognizing TTP's neurological symptoms mimicking stroke is crucial to avoid misdiagnosis and ensure timely treatment.