P2.037: Libman-Sacks Endocarditis in An Adolescent with Acute Promyelocytic Leukemia: A Case Report

Introduction: Libman-Sacks endocarditis (LSE), also known as nonbacterial thrombotic endocarditis (NBTE), is characterized by sterile, non-infectious vegetations on cardiac valves. LSE is commonly associated with Systemic Lupus Erythematosus (SLE) and Anti-Phospholipid Syndrome (APS), but can also be seen in malignancy, likely due to the associated hypercoagulable states. Malignancy-induced LSE has been rarely reported in the pediatric population.

Case Description: Our case involves a 14-year-old male presenting to the ED with fever, tachycardia, respiratory distress, and concern for sepsis. Workup was significant for pancytopenia, neutropenia, and elevated LDH, ultimately leading to the new diagnosis of acute promyelocytic leukemia (APL). His hospitalization was complicated by ARDS, human metapneumovirus, cerebritis, pulmonary hemorrhage, non-sustained monomorphic VT managed with lidocaine and amiodarone, and aspergillus detected on skin biopsy. At time of admission, patient’s troponin was elevated at 379 ng/L, but down trended to 196.5 ng/L over four days.
Initial echocardiogram at time of admission showed no vegetations or ventricular dysfunction. On day 9, visualization of a new thickening on the posterior mitral valve leaflet (~10 x 7 mm in size) was concerning for developing vegetation. By day 13, a new aortic valve vegetation (~9 x 8 mm) with trivial insufficiency was seen.
The patient’s CRP was slightly elevated at 62 with normal procalcitonin at time of admission, with negative blood cultures throughout the hospital course. Given the presence of malignancy and absence of significant infectious signs or autoimmune markers, LSE was the likely diagnosis. The patient was started on Rivaroxaban 15 mg daily with biweekly echocardiography. The vegetations remained stable on follow-up imaging, with preserved biventricular function and absence of significant aortic or mitral valve regurgitation or stenosis.
Dexamethasone was used for the management of differentiation syndrome, a complication of the APL therapy, but no other immunosuppressants were initiated. The patient remains extubated and stable on Rivaroxaban and chemotherapy-free regimen of all-trans retinoic acid (ATRA) and arsenic trioxide for APL.

Discussion: In literature, LSE has been traditionally associated with autoimmune disease in the pediatric community. In the adult population, LSE attributed to cancer-induced hypercoagulability is becoming more widely acknowledged. Pediatric LSE without autoimmune disease is rarely reported, but this case highlights the need for a broad differential in cases of malignancy with endocarditis. Timely recognition is vital to prevent embolic complications and allow for appropriate anticoagulant initiation. Additionally, distinguishing LSE from infectious endocarditis helps avoid unnecessary prolonged antibiotic use in patients.

Conclusion: This case demonstrates that LSE can be a non-infectious cardiac complication of pediatric malignancies. When non-infectious valvular vegetations appear in patients with malignancies, LSE should be considered in the differential. Early recognition and appropriate management may help prevent complications, avoid surgery, and reduce misdiagnosis and potential use of prolonged antibiotics.