A Rare Case of Delirium: Acquired Thrombotic Thrombocytopenic Purpura in an HIV Patient

Introduction

Thrombotic thrombocytopenic purpura (TTP) is a rare disorder with incidence of one in a million. Manifestations of TTP include fever, thrombocytopenia, thrombotic microangiopathy affecting the brain, heart and kidney causing neurological symptoms, and hemolytic anemia. Not all patients with TTP will have each and every manifestation, and therefore a high index of suspicion is necessary when managing a patient with microangiopathic hemolytic anemia and thrombocytopenia. In recent years, increased incidence of TTP has been reported in patients with coexisting Human immunodeficiency virus (HIV)infection .

Clinical Case

A 55 year old female with unknown past medical history presented with confusion and altered sensorium after she was found in the airport wandering. When questioned, she was oriented to self only, and gave single phrase answers.

Vitals on admission were significant only for tachycardia with HR of 125 beats per minute. Rest of physical exam was normal. Lab work revealed severe anemia (Hemoglobin 5.1), thrombocytopenia ( Platelet count 6), borderline renal function( BUN 30, serum Creatinine 1.1) and Schistocytes on peripheral smear. TTP was the presumptive diagnosis. Without evidence of sepsis, she was treated with intravenous fluids, systemic steroids, blood products (pure red cell concentrate and fresh frozen plasma) and plasmapheresis. Patient was found to be HIV positive, and had acquired immunodeficiency syndrome with CD4 count of 193. ADAMTS13 inhibitor was 1.3 (nl <0.4) and ADAMTS13 activity level was <3 (normal range 68-163%).

Patient's mental status improved to baseline over next 3 days and, renal failure and encephalopathy resolved. Upon further investigation, she recalled having a needle stick injury around 10 years ago. She was started on elvitegravir, cobicistat, emtricitabine, and tenofovir alafenamide (Genvoya) and prophylactic antibiotics prior to discharge.

Discussion

Despite its rare nature, TTP can be fatal if one fails to make a proper timely diagnosis. If left untreated, the mortality can reach up to 90% but with empiric treatment and therapeutic plasma exchange up to 85% survival rate can be achieved.

Through this case report, we hope to raise the awareness of this disorder with its particular association with HIV infection. The exact mechanism for HIV related TTP is unknown, but some proposed ones include the release of large amounts of von Willebrand factor and downregulation of ADAMTS13 and/or the production of antibodies against ADAMTS13. ADAMTS13 activity levels below 10% are seen in acquired and hereditary TTP, but not all patients with such exhibit low levels with this assay. Acquired TTP with low levels of ADAMTS13 has been increasingly reported in association with HIV infection, such as in this case.