Acute Promyelocytic Leukemia Masquerading as Antiphospholipid Syndrome in a Woman with SLE

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Introduction: The increased risk of thrombotic events in systemic lupus erythematosus (SLE) is well-known, notably associated with antiphospholipid antibodies. Conversely, DIC is a typical presentation of acute promyelocytic leukemia (APL). However, there is increasing evidence of major thromboses at APL presentation. We present a rare case of APL with multiple macrothrombi in a woman with SLE, initially diagnosed as catastrophic antiphospholipid syndrome (CAPS).

Description: A 69-year-old female with recent diagnosis of SLE, presented with shortness of breath. On arrival, she was tachycardic, hypotensive, and hypoxic. CT scan revealed bilateral occlusive pulmonary emboli and was started on heparin. On arrival to our hospital, she was started on norepinephrine and vasopressin. POCUS revealed a large, dilated right ventricle with plump IVC. There was superficial thrombophlebitis over her lower extremities bilaterally. Given suspicious thromboses in multiple areas in the setting of known SLE, a preliminary diagnosis of CAPS was made and the apheresis service was consulted for emergent therapeutic plasma exchange. Due to ongoing hemodynamic instability, she was placed on VA-ECMO in setting of massive PE with obstructive shock. She was subsequently intubated. She developed spontaneous bleeding from multiple sites including lips, gums, and cannulation sites. Heparin was stopped and she was started on a massive transfusion protocol. That evening, hematopathology called with peripheral smear results indicative of acute promyelocytic leukemia. Plans were made to start all-trans retinoic acid and place on renal replacement therapy in setting of rapidly developing hyperkalemia, likely secondary to tumor lysis syndrome. Unfortunately, she suffered a cardiac arrest while on ECMO. ACLS was performed for 20 minutes, and unfortunately ROSC was not achieved.

Discussion: Macrothrombi in SLE, particularly in the setting of CAPS, is a widely acknowledged clinical manifestation in patients with SLE. Acute macrothrombi as the presenting symptom of APL is a much less common phenomenon. Our case describes this rare presentation of APL in a woman with SLE where a diagnosis of CAPS was far more probable. This case adds to the growing literature of APL presenting with macrothrombosis at time of diagnosis.