Case Presentation: A 77-year-old African-American male with Adult-onset Still’s disease (AOSD) was admitted at the hospital for severe thrombocytopenia. The patient had been diagnosed with AOSD four years before this hospital admission. His AOSD was well-controlled with anakinra, an interleukin-1 receptor antagonist, and low-dose prednisone. On admission, the patient did not have any neurological manifestation. Additional laboratory workup revealed direct Coombs test negative hemolytic anemia. However, his initial peripheral blood smear did not show significant schistocytosis.

The patient developed confusion at the third day of his hospitalization. His repeated peripheral smear showed a significant number of schistocytes. A presumptive diagnosis of thrombotic thrombocytopenic purpura (TTP) was made, and plasmapheresis was initiated. Later on, his ADAMTS13 activity level was found to be less than 3% (reference range: 68–163% activity) and the diagnosis of TTP was confirmed. His ADAMTS13 inhibitor level was 1 inhibitor unit (reference: <0.4 inhibitor unit), which confirmed the diagnosis of acquired TTP. The patient’s symptoms and lab values normalized with plasmapheresis. The patient had regular follow-up appointments with his hematologist for two months. Unfortunately, the patient was lost to follow-up after that.

Six months later, the patient was found unresponsive while living unsupervised in his apartment. The patient was brought to the emergency room. Laboratory evaluation revealed platelet count of 9,000/mcL, hemoglobin of 9 gm/dL, lactic acid level of 3.1 mmol/L, and troponin of 5.73 ng/mL. A presumptive diagnosis of recurrent TTP was made. Unfortunately, his clinical condition deteriorated quickly and he died of cardiac arrest in the emergency room. 

Discussion: Pathogenesis of both TTP and AOSD involves dysregulation of the immune system. Although multiple case reports have been published describing coexistence of TTP and AOSD, recurrent TTP associated with AOSD had rarely been reported. Awareness of this rare, life-threatening complication of AOSD among hospitalists is important, because a significant percentage of these patients are hospitalized; and untreated TTP has a case fatality rate of approximately 90%. With early initiation of plasmapheresis, the case fatality of TTP could be reduced to 10–20%. Hence, early recognition and initiation of treatment is pivotal in management of TTP. TTP patients rarely present with the classic pentad of thrombocytopenia, microangiopathic hemolytic anemia, neurological abnormalities, renal failure, and fever. Rarely, the initial peripheral blood smear may not show significant number of schistocytes. Repetition of the tests is necessary when clinical suspicion is high. As TTP associated with AOSD has significant chance of recurrence, we emphasize on importance of arrangement of close follow-up, especially for the vulnerable groups of patients like geriatric population. 

Conclusions: Both thrombotic thrombocytopenic purpura (TTP) and Adult-onset Still’s disease (AOSD) are fairly uncommon diseases. Coexistence of these conditions is rare and potentially life threatening. Early initiation of plasmapheresis significantly reduces the case fatality of TTP. Hence, we emphasize the importance of early recognition of TTP in AOSD patients. In many occasions, a high index of suspicion is necessary. A close follow-up is also warranted for the early identification of recurrence of TTP in AOSD patients.