Thrombotic thrombocytopenic purpura associated with acalculous cholecystitis masquerading as immune thrombocytopenia

Thrombotic thrombocytopenic purpura (TTP) is a potentially life-threatening condition characterized by thrombocytopenia, microangiopathic haemolytic anaemia, and end-organ ischemia. Association of TTP with acute cholecystitis is rare, with only two cases reported in literature. We report the third case of TTP associated with acute cholecystitis in an African-American female with systemic lupus erythematosus (SLE). She presented with fever and abdominal pain; laboratory testing revealed acute on chronic thrombocytopenia, and imaging confirmed acute acalculous cholecystitis. This initially led to a misdiagnosis of immune thrombocytopenia (ITP), and she was treated with antibiotics, intravenous immunoglobulin, and steroids without improvement. She subsequently developed neurological symptoms with laboratory evidence of haemolysis raising a concern for thrombotic microangiopathy. Emergent plasmapheresis was initiated for suspected TTP, resulting in improvement of her symptoms. Low ADAMTS13 activity subsequently confirmed the diagnosis. This case highlights the importance of recognizing atypical presentations of TTP to initiate prompt life-saving treatment.