Gamma-Delta Hepatosplenic T-Cell Lymphoma in a Two-Year-Old: A Case Report.

Gamma-delta (γδ) hepatosplenic T-cell lymphoma (HSTCL) is a rare, aggressive malignancy that is exceptionally uncommon in young children. It often presents with nonspecific symptoms that delay diagnosis. We describe a previously healthy 26-month-old girl who developed daily fevers, weight loss, decreased appetite, and progressive lower-extremity weakness leading to loss of ambulation. Examination revealed marked hepatosplenomegaly without lymphadenopathy, and laboratory studies showed lymphocytic leukocytosis with evolving cytopenias. Bone marrow evaluation identified a clonal γδ T-cell population, and liver biopsy confirmed sinusoidal infiltration, establishing the diagnosis of γδ HSTCL. Her clinical course was characterized by poor response to multiple induction, consolidation, and targeted therapies. She presented with persistent minimal residual disease (MRD), requiring repeated treatment escalation and substantial supportive care. This case illustrates the diagnostic difficulty and therapeutic resistance of pediatric γδ HSTCL. Early recognition, molecular characterization, and timely consideration of possible stem cell transplant are essential to improving outcomes in this rare and highly aggressive pediatric lymphoma.