Inflammatory pseudotumor (IMT) of urinary bladder - a case report

Inflammatory myofibroblastic tumor (IMT) is an entity of unknown histogenesis occurring at various sites, such as lung, liver, orbit, oral cavity, salivary glands, abdomen, urinary bladder and prostate. In the genito-urinary tract, it commonly occurs in the bladder. Histologically it is characterised by a less cellular mass composed of an edematous, myxoid stroma in which spindle shaped myofibroblastic cells and chronic inflammatory cells are seen distributed diffusely throughout the lesion. Focal cytologic atypia of myofibroblasts and the tendency to infiltrate into muscle layer of bladder and perivesical soft tissue gives a sarcomatous appearance to these lesions, causing diagnostic difficulty to the surgical pathologist. Hence it is categorised into the group of pseudosarcomatous proliferations of bladder, along with postoperative spindle cell nodule. Though, histologically both the lesions are similar, IMT occurs in the absence of previous instrumentation, biopsy or surgery. Surgery is the main stay of treatment for this condition and this lesion is associated with good prognosis with minimal risk of recurrence and no risk of metastasis. Its histological significance lies in its sarcomatous features and the importance in which this lesion needs to be differentiated from sarcomatoid carcinoma and sarcomas of urinary bladder. The reported An aplastic lymphoma kinase - 1 (ALK-1) positivity varies from 48 - 89 percent, and the corresponding geneticre arrangement of ALK gene also varies from negative in all cases to positive in few cases. Hence, whether the lesion is a reactive process or a true neoplasm is still unresolved with conflicting reports in the literature regarding its neoplastic nature.