Mixed-phenotype leukemia with TCF3::ZNF384 fusion presenting as an isolated mediastinal mass.

Acute leukemia with TCF3::ZNF384 is a distinct type of acute leukemia that present most commonly as B-acute lymphoblastic leukemia or mixed-phenotype acute leukemia (B/myeloid). We report the first case of TCF3::ZNF384 mixed-phenotype leukemia presenting as isolated extramedullary disease in the mediastinum. Diagnosis using RNA-sequencing and whole genome sequencing on the primary issue is illustrated.