Perinephric Abscess Extending to the Psoas Muscle and Causing a Nephro-Cutaneous Fistula.

We present a case of a 76-year-old male with dementia transferred from a nursing home with a fever and an abscess on his back. Workup revealed an extensive perinephric abscess, which extended to his psoas muscle, with an additional fistula to his back where the abscess was noted. The extent and tracking of the perinephric abscess were unusual as well as the organisms isolated, and species.