Protracted clinical course of an AFF1 fusion positive uterine smooth muscle tumor causing diagnostic confusion over a course of 15 years

•Histologic diagnostic criteria alone for uterine smooth muscle tumors lacks robust prognostication.•Molecular/genetic techniques should be advocated to further investigate unusual case presentations.•Novel identification of a PTP4A2-AFF1 genetic fusion was identified.•The novel PTP4A2-AFF1 genetic fusion may have further diagnostic prognostic, and therapeutic implications.