Spontaneous resolution of inflammatory myofibroblastic tumor of the kidney

Inflammatory myofibroblastic tumor (IMT) of the kidney is a rare and benign condition often confused with renal malignancy based on clinical presentation and radiologic evaluation that has commonly been treated with nephrectomy. Utilizing renal mass biopsy to help diagnose and guide therapeutic intervention is increasing but has not been universally adopted to this point. We present a case of an incidentally found atypical renal mass in a 71-year-old female diagnosed as inflammatory myofibroblastic tumor of the kidney after core needle biopsy. This tumor was managed conservatively without surgical intervention and resolved spontaneously.