A Case Report of Immunosuppressant Medication‒Associated Polyarticular Tophaceous Gout Successfully Treated Using the Polyethylene Glycol‒Conjugated Uricase Enzyme Pegloticase.

This case describes a female patient with polyarticular tophaceous gout who was given transplant immunosuppressant medications. The 36-year-old was treated for Wilms tumor at 3 years of age by operative removal of 1 kidney, chemotherapy, and radiotherapy. At age 19, the patient was diagnosed with cardiomyopathy attributed to prior chemotherapy and radiotherapy. She underwent a heart transplant at age 22 and has received prednisone, mycophenolate mofetil, and cyclosporine to prevent rejection since the transplant. The patient presented with numerous gouty tophi and elevated serum uric acid, likely precipitated by her immunosuppressant medications, and underwent a 38-week course of pegloticase infusions at 2-week intervals. After the first infusion, her serum uric acid decreased to <89 μmol/L (<1.5 mg/dL) and remained at this level throughout treatment. Her proximal tophi, and subsequently distal tophi, resolved over the course of treatment; she did not report any gout flares. The patient reported improved mobility, pain, and quality of life on completion of therapy. Immunosuppressant medications necessary for transplant viability potentially reduced her immunologic response to pegloticase therapy by inhibiting the development of anti-pegloticase antibodies.