Graves disease following rabbit antithymocyte globulin treatment of severe aplastic anemia in a Korean child

Evolution of Graves' Disease during Immune Reconstitution following Nonmyeloablative Haploidentical Peripheral Blood Stem Cell Transplantation in a Boy Carrying Germline SAMD9L and FLT3 Variants

Graves’ disease, characterized by hyperthyroidism resulting from loss of immune tolerance to thyroid autoantigens, may be attributable to both genetic and environmental factors. Allogeneic hematopoietic stem cell transplantation (HSCT) represents a means to induce immunotolerance via an artificial immune environment. We present a male patient with severe aplastic anemia arising from a germline SAMD9L missense mutation who successfully underwent HSCT from his HLA-haploidentical SAMD9L non-mutated father together with nonmyeloablative conditioning and post-transplant cyclophosphamide at 8 years of age. He did not suffer graft-versus-host disease, but Graves’ disease evolved 10 months post-transplant when cyclosporine was discontinued for one month. Reconstitution of peripheral lymphocyte subsets was found to be transiently downregulated shortly after Graves’ disease onset but recovered upon antithyroid treatment. Our investigation revealed the presence of genetic factors associated with Graves’ disease, including HLA-B*46:01 and HLA-DRB1*09:01 haplotypes carried by the asymptomatic donor and germline FLT3 c.2500C>T mutation carried by both the patient and the donor. Given his current euthyroid state with normal hematopoiesis, the patient has returned to normal school life. This rare event of Graves’ disease in a young boy arising from special HSCT circumstances indicates that both the genetic background and the HSCT environment can prompt the evolution of Graves’ disease.

Graves' disease following allogenic hematopoietic stem cell transplantation for severe aplastic anemia: case report and literature review

BACKGROUND

Similar autoimmune processes (defective T-cell function) take place during the pathogenesis of aplastic anemia (AA) and Graves' disease (GD). Antithyroid drugs used for the management of GD may induce AA and GD may occur following treatment of severe aplastic anemia (SAA).

CASE PRESENTATION

Clinical and laboratory investigations were performed for an 11-year-and-2-month-old girl who was referred for bilateral exophthalmus and abnormal thyroid function tests. She had been diagnosed as having severe acquired AA at the age of 8 years and had been treated with allogenic hematopoietic stem cell transplantation from her healthy human leukocyte antigen-matched sibling donor. Clinical examination revealed a weight of 32.6 kg (-0.88 standard deviation [SD] score); height, 145.7 cm (-0.14 SD score); body mass index 15.5 kg/m2 (-1.01 SD score); heart rate, 110/min; blood pressure, 128/74 mmHg; bilateral exophthalmos and an enlarged thyroid gland. The laboratory workup showed hemoglobin of 11.1 g/dL; white blood cells, 7500/mL; platelets, 172,000/mL; free thyroxine (FT4), 4.80 ng/dL (normal, 0.5-1.51); free triiodothyronine (FT3), 17.7 pg/mL (normal, 2.5-3.9); thyrotropin (TSH), 0.015 mIU/mL (normal, 0.38-5.3); antithyroglobulin peroxidase (TPO) antibody, 61.7 IU/mL (normal, 0-9); antithyroglobulin (TG) antibody, <0.9 IU/mL (normal, 0-4) and thyrotropin (TSH) receptor antibodies 14 U/L (normal, 0-1). Doppler ultrasonography showed diffuse enlargement of the thyroid gland and increased vascularity. She was treated with methimazole (0.6 mg/kg/day). L-thyroxine treatment was also needed (50 μg/day). Thrombocytopenia developed during follow-up. A thyroidectomy was performed for definitive treatment at the 14th month of treatment.

CONCLUSIONS

The association of hyperthyroidism and AA in the pediatric age group is rare. The long-term use of antithyroid drugs and radioactive iodine should be avoided due to their hematologic toxic side effects.