Inflammatory myofibroblastic tumor (IMT) previously known as inflammatory pseudotumor, plasma cell granuloma, pseudosarcoma, myxoid hamartoma or inflammatory myofibrohistiocytic proliferation is recently recognized by World Health Organization (WHO) as "IMT" and is considered as a rare benign tumor of soft tissues occurring commonly in lung, liver and mesentry and omentum. IMT is mainly identified as a lesion of children and young population. In this report, we describe a rare case of IMT occurring in a 93-year-old female in urinary bladder with initial benign presentation but demonstrating rapid malignant transformation as confirmed with morphology and immunohistochemical (IHC) stains. Our report highlights the importance of close follow for IMT showing malignant transformation along with utility of IHC stains to evaluate the degree of malignant transformation in such cases.