Inflammatory myofibroblastic tumors IMTs

Anaplastic lymphoma kinase (ALK) is a cytoplasmic membrane tyrosine kinase receptor expressed in anaplastic large cell lymphoma. ALK expression has been detected in about two thirds of inflammatory myofibroblastic tumor (IMT) of the urinary tract, also termed postoperative spindle cell nodule, inflammatory pseudotumor, and pseudosarcomatous fibromyxoid tumor. 

We limit our discussion here to two of the benign mim-ickers of bladder tumors nephrogenic adenoma as a mimic of both urothelial carcinoma and adenocarcinoma and inflammatory myofibroblastic tumor (IMT) as mimic of sarcomatoid carcinoma or sarcomas. 

An inflammatory myofibroblastic tumor (IMT) of the bladder may arise either spontaneously or as a result of a prior instrumentation of the bladder. IMTs are benign mesenchymal neoplasms composed of a proliferation of relatively monotonous myofibroblastic cells (typical tissue culture appearance) in a richly vascularized background with red blood cell extravasation and lym-phoplasmacytic inflammatory infiltrate. Mitotic activity ranges from absent to brisk. Abnormal mitotic figures... 

CIST, gastrointestinal stromal tumor IMT, Inflammatory myofibroblastic tumor N, negative PR, progesterone receptor S, sometimes positive SFT, solitary fibrous tumor SMA, smooth muscle actin SS, stromal sarcoma +, almost always positive. 

ALK, anaplastic lymphoma kinase EMA, epithelial membrane antigen IMT, inflammatory myofibroblastic tumor MSA, muscle-specific actin +, almost always positive S, sometimes positive N, negative. 

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