AbstractAbstract 4828Acute lymphoblastic T-cell leukemia (T-ALL) accounts for nearly 15% of newly diagnosed cases of childhood acute lymphoblastic leukemia (ALL). Historically, T-ALL has conferred a worse prognosis than other forms of ALL. Although multi-agent pulse chemotherapy has improved EFS over the past several decades, the lack of clinical or laboratory based prognosticators as well as high rate of relapse have remained barriers in management. Described is a case of acute lymphoblastic T-cell leukemia in a previously healthy sixteen-year-old girl initially presenting with galactorrhea and hyperprolactinemia without evidence of CNS infiltrate. Although galactorrhea has been described in a few adults as an initial presentation of acute myeloginous leukemia (AML) and a single adult case of T-cell lymphoma, to date there has been no association with childhood cancers or T-ALL in particular. Hypothesized in AML cases as a rare paraneoplastic phenomenon, this case explores this theory and employs direct prolactin staining of tumor cell cytoplasm, serial prolactin monitoring throughout treatment, and investigation into underlying causes for hyperprolactinemia in the context of T-ALL. The possibilities for prolactin as a novel tumor marker are explored. Disclosures:No relevant conflicts of interest to declare.