Inflammatory myofibroblastic tumors of urinary bladder and kidney

Inflammatory myofibroblastic tumor (IMT)
Most of IMT of urinary tract involves bladder
More common in male than female (2:1), mean age 53 yr, younger than urothelial ca
Histology: bland spindle cells with myxoid and fascicular growth
lymphoplasmacytic inflammation; ALK expression
Anterosuperior wall of urinary bladder
Ring enhancement in bladder mass
Tumor cells in the periphery, loose stroma in the center
Nonspecific findings for renal IMT c smooth margin