TTP-Like Syndrome and Subsequent Non-Aneurysmal Subarachnoid Hemorrhage in HbSC Disease: A Case Report.

Sickle cell disease (SCD) with hemoglobin- (Hb-) SC genotype is often considered a milder SCD variant, yet life-threatening complications can occur. A 26-year-old man with HbSC disease presented with an infection triggered vaso-occlusive crisis (VOC), acute chest syndrome (ACS), severe thrombocytopenia, Coombs-negative hemolysis with schistocytes, acute kidney injury, and markedly elevated lactate dehydrogenase (LDH) in the setting of Klebsiella pneumoniae sepsis. The resulting severe thrombotic microangiopathy- (TMA-) like phenotype initially raised concern for thrombotic thrombocytopenic purpura (TTP). However, ADAMTS13 activity was not significantly reduced, arguing against classical TTP. The episode was interpreted as a TTP-like syndrome, whereas fat embolism syndrome (FES) remained an important differential diagnosis. The patient received red-cell exchange, plasma exchange, caplacizumab, antibiotics, and dialysis, followed by hematologic and renal recovery. Months later, he developed a non-aneurysmal infratentorial subarachnoid hemorrhage (SAH) with obstructive hydrocephalus requiring external ventricular drainage (EVD) and posterior fossa decompression, resulting in severe persistent neurological disability. The case, therefore, highlights the severity of HbSC disease and the challenge of urgent treatment decisions under substantial diagnostic uncertainty when a TMA-like presentation overlaps with other severe SCD complications such as FES.