Simultaneous Development of Thrombotic Thrombocytopenic Purpura and Immune Thrombocytopenia in a Pediatric Patient with Systemic Lupus Erythematosus.

Patients with systemic lupus erythematosus can experience multiple hematological complications. Autoimmune hemolytic anemia, immune thrombocytopenia (ITP) and thrombotic thrombocytopenic purpura (TTP) have been described in patients with this disease. Hematologic abnormalities may precede joint or renal manifestations of the disease. In TTP, decrease in the level of von Willebrand cleaving protease (ADAMTS13) activity and the presence of an inhibitor to this enzyme have been shown to correlate with disease activity. For the diagnosis of ITP, the presence of platelet antibodies is not required, but they are strongly suggestive of the diagnosis in combination with a falling platelet count. We present a young lady who developed multiple hematological abnormalities simultaneously against a background of well-controlled SLE. WC is a 13 yo female who was diagnosed with SLE after developing lupus nephritis at the age of 12. She was treated successfully with immunosuppression and had been maintained on cyclophosphamide every three months. At a routine clinic visit, a CBC was obtained that showed a hemoglobin of 6.7 g/dL, white blood cells of 7,500/mm³ and platelets of 22,000/mm³. Reticulocyte count was 18.8%. Direct antiglobulin test was negative. The patient complained of fatigue and headache of one week’s duration. The peripheral blood smear showed 7–10 schistocytes per high power field and thrombocytopenia. A complete blood count performed one month prior to this visit showed a hemoglobin of 11.6 gm/dL and a platelet count of 353,000/mm³. The patient underwent plasmapheresis for 5 days for a presumptive diagnosis of TTP. She responded to plasmapheresis with increase in her hemoglobin level to 10.2 gm/dL and platelets to 153,000/mm³. On laboratory examination obtained prior to beginning plasmapheresis therapy, anti-platelet IgM antibody titer was elevated; ADAMTS13 inhibitor was elevated at 0.9 inhibitor units, and ADAMTS13 activity was decreased at 30%. After cessation of plasmapheresis the patient’s platelet count decreased over one week to a nadir of 74,000/mm³. However, the patient’s hemoglobin increased to 11.1 gm/dL over that same time period. Haptoglobin was normal at this time at 142 mg/dL. Lactate dehydrogenase was also normal at 204 U/L. No schistocytes were evident on peripheral blood smear. Therefore, we felt that the patient at this point was experiencing autoimmune destruction of her platelets only, without active TTP. The patient was monitored closely and her platelet count increased to 214,000/mm³ without intervention. She currently has stable blood counts in the normal range. This case is an unusual example of the hematological complications of SLE with the simultaneous development of two abnormalities in one patient. In this situation, presence of anti-platelet antibody and the stability of the patient’s hemoglobin prevented reinitiation of plasmapheresis. The measurement of anti-platelet antibody was obtained as part of the screening laboratory examination for lupus and would not normally have been obtained in a patient with this clinical picture who presented to our clinic. This raises the questions of how often multiple autoantibodies coexist in these complex patients with SLE and whether we should consider examining for them more closely at the time of development of hematological abnormalities or at diagnosis of their rheumatologic disease.