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Serum sickness after antithymocyte globulin administration in a cardiac transplant patient.

CLINICAL HISTORY A 57-year-old gentleman with allo-geneic heart transplantation for nonischemic cardiomyopathy developed nonspecific graft dysfunction 3 years posttransplant. He had no documented cellular or antibody-mediated rejection, graft vasculopathy, and donor-specific antibodies on panel reactive antibody testing. Plasmapheresis and IV immunoglobulin infusions were initiated in addition to increases in maintenance immuno-suppression therapy with no significant impact on his reduced ejection fraction. Because of recurrent presentations of decompensated heart failure despite escalation of care, ATG therapy was initiated with 75 mg of IV rabbit ATG daily for 3 days followed by 50 mg IV for 1 day. Nine days after IV thymoglobulin therapy, he presents with fever, chills, lip swelling, and myalgias. Physical examination revealed mild congestive heart failure and an erythematous and pruritic maculopapular rash. He had tender polyarthritis in his extremities with significant restriction to active and passive range of motion (Fig. 1). Laboratory investigations revealed mild leukocytosis, elevated C-reactive protein, and acute renal insufficiency with no evidence of active sediments on urinalysis. Cytomegalovirus testing was unremarkable. Based on this inflammatory presentation and clinical context, he was diagnosed with SS secondary to IV ATG and started on IV methylprednisolone 1 g daily for 6 days. Failing to show significant improvement at 48 hours, plasmapheresis was initiated for 5 days with marked symptomatic relief after the first exchange. He was discharged home on his 10th day of admission with complete resolution of his presenting symptoms.