Case Report: Juvenile dermatomyositis complicated by acute myeloid leukemia: achievement of sustained remission through hematopoietic stem cell transplantation.

Juvenile dermatomyositis (JDM), a pediatric subtype of idiopathic inflammatory myopathy, is a relatively rare rheumatic and immune system disease among children. Although paraneoplastic dermatomyositis (DM) has been documented in adult malignancies, its association with acute myeloid leukemia (AML) in pediatric populations remains exceptionally rare. We present a male patient diagnosed with JDM at age 6, characterized by Gottron's papules and muscle weakness. Despite receiving sequential immunosuppressive therapies and biological agents, the disease followed a relapsing-remitting course over 9 years. At age 15, he developed persistent knee arthralgia accompanied by intermittent fever lasting 8 days. Hematologic evaluation revealed thrombocytopenia (platelet count: 76 ×109/L) and leukocytosis (white blood cell count: 36.46 ×109/L), prompting bone marrow aspiration confirmed AML diagnosis (French-American-British M2 subtype). Following induction chemotherapy and two consolidation cycles, allogeneic hematopoietic stem cell transplantation (HSCT) from a matched unrelated donor was successfully performed. Notably, both JDM symptoms and AML achieved sustained remission at 1-year follow-up post-HSCT. This case suggests that HSCT may represent a potential therapeutic approach for refractory autoimmune-hematologic malignancy overlap syndromes, though further studies are required to validate its efficacy.