Expanding the molecular spectrum of congenital mesoblastic nephroma: A rarely described KIAA1549::BRAF fusion in a classic variant

Congenital mesoblastic nephroma (CMN) are low grade spindle cell neoplasms with myofibroblastic differentiation and are classified morphologically as classic, cellular, or mixed. Recurrent genetic alterations have been identified – EGFR internal tandem duplication is associated with classic morphology, and ETV6::NTRK3 fusion is associated with the cellular subtype. We report a case of a classic variant of CMN with a rarely described KIAA1549::BRAF fusion.