Passenger Lymphocyte Syndrome with Hepatic Sinusoidal Obstruction Syndrome in an Infant Following Living Donor Liver Transplantation: An Association or Coincidence?

A 7-month-old male infant with AB blood type, diagnosed with biliary atresia and uncompensated cirrhosis postKasai procedure, underwent living donor liver transplantation with a 260-g left lateral segment graft from a blood type B donor. Intraoperatively, the patient received a transfusion of type AB red blood cells. Immunosuppressive therapy included tacrolimus and prednisone. The recovery period was uneventful until postoperative day 18, when the patient developed a fever, changed mental status, and impaired liver functions. Further tests revealed an increased bilirubin level, decreased hemoglobin and platelet counts, detectable anti-A antibodies, and a positive direct Coombs test. A considerable increase in B lymphocytes indicated a diagnosis of passenger lymphocyte syndrome (PLS), which was managed with adjustments to immunosuppression, intravenous immunoglobulin infusion, type B red blood cell transfusion, and supportive care. Interestingly, 1 month after the diagnosis of PLS, a routine computed tomography angiography showed an enlarged liver with patchy enhancement and obscured hepatic veins. Based on the presence of ascites, the clinical diagnosis of hepatic sinusoidal obstruction syndrome (HSOS) was established. Management included transitioning from tacrolimus to cyclosporine and administering low-molecular-weight heparin injections. The condition of the patient improved over 3 weeks, and subsequently, the patient was discharged. To conclude, this report raises the question of a potential correlation between PLS and HSOS in this patient. While PLS is not presently recognized as an established cause of HSOS, the lymphocyte proliferation and antibody production found in PLS can potentially damage the hepatic sinusoidal endothelial cells.