Post-transplant autoimmunity in a child: a lupus-like syndrome emerging in the context of chronic graft-versus-host disease.

BACKGROUND: Autoimmune manifestations are increasingly recognized as late complications following hematopoietic stem cell transplantation (HSCT), particularly in association with chronic graft-versus-host disease (cGvHD). However, the occurrence of systemic lupus erythematosus (SLE)-like features remains extremely rare, especially in pediatric patients. Understanding the mechanisms underlying such manifestations, including the role of mixed chimerism, is important for early recognition and management.

CASE PRESENTATION: We report the case of a girl with thalassemia major who underwent HSCT from a fully matched unrelated donor at the age of six years. Her early post-transplant course was complicated by gastrointestinal cGvHD, followed by autoimmune hemolytic anemia and arthritis, which responded to corticosteroids and methotrexate. Four years post-HSCT, she developed a lupus-like syndrome characterized by malar rash, serositis, cytopenias, arthritis, high-titer antinuclear antibodies (ANA), elevated anti-double-stranded DNA (anti-dsDNA) antibodies, and low complement levels, fulfilling the American College of Rheumatology classification criteria for SLE. At the time of symptom onset, mixed chimerism was documented, with a notable proportion of recipient-derived lymphocytes. Treatment with mycophenolate mofetil and hydroxychloroquine led to rapid clinical and laboratory improvement.

CONCLUSION: This case illustrates the evolving nature of post-transplant immune dysregulation and suggests that declining donor chimerism may contribute to the reactivation of autoreactive lymphocytes, leading to atypical autoimmune manifestations. In pediatric patients presenting with unusual post-transplant symptoms, careful clinical assessment and immune monitoring may aid in timely diagnosis. Individualized immunosuppressive therapy can facilitate symptom control and support favorable long-term outcomes.