Castleman Disease is a rare non-clonal lymphoproliferative disorder that predisposes towards adults with very few reported cases in children. Presented is a 12-year-old male with progressive abdominal pain, vomiting, and fever. Laboratory testing showed elevated inflammatory markers, hemolysis, kidney injury, coagulopathy, thrombocytopenia, and refractory hypocalcemia. Imaging demonstrated an adrenal mass, hepatosplenomegaly, generalized lymphadenopathy, and increased bone marrow uptake without focality. The diagnosis of Castleman Disease was made with tissue biopsy and marked disease regression occurred after high dose steroids and interleukin-6 inhibition. Awareness of Castleman disease in a pediatric patient is essential to providing adequate and timely care.