A review of previously published IMT patients of all ages found that: 1) 4 patients (3 with unifocal, 1 with multifocal disease) without prior treatment had complete responses to crizotinin; 2) 2 patients (1 with unifocal, 1 with multifocal disease) that had persistent disease after surgery and previously treated with chemotherapy had partial responses to crizotinib while 1 patient previously treated with a corticosteroid, prednisone, continued to have progressive disease on crizotinib; and 3) 6 patients with progressive disease after surgery (due to multifocal or unifocal disease in inaccessible sites) had complete responses (2 cases), partial responses (2 cases), stable disease (1 case), or progressive disease (1 case) in response to crizotinib. Two of these crizotinib-treated patients with progressive disease had near complete responses to second generation ALK inhibitors Another study reviewed 29 pediatric patients (age 15 months to 17 years) who were treated with an ALK inhibitor followed by surgical removal of the tumor (5 cases), surgical tumor removal followed by an ALK inhibitor (12 cases), or an ALK inhibitor without surgery. Twelve patients had complete responses, 14 partial responses, 2 stable disease, and 2 recurrences after finishing ALK inhibitor treatment. The latter two patients obtained complete responses to retreatment with crizotinib (1 case) or a second generation ALK inhibitor, ceritinib (1 case). A study of 14 pediatric patients with metastatic or inoperable ALK-positive IMT were treated with crizotinib: 5 patients obtained complete responses, 7 partial responses, and 2 stable disease. Over the study period (2–63 months), no patient developed progressive disease.
In all events, IMT is a rare tumor with a reported incidence in 2009 of 150–200 cases/year in the United States.IMT lesions typically consist of, and are defined by, myofibrolastic spindle cells, i.e. specialized cells that are longer than wide, have a microscopic appearance that merges the appearances of fibroblasts and smooth muscle cells (see myofibroblast), occur in normal as well as tumor tissues, and in normal tissues are commonly designated  fibroblasts. However, the lesions in some IMF cases are dominated by sheets of epithelioid cells (which may have rounded shapes) with only a minor component of spindle cells. Tumors with these characteristics  are regarded as a subtype of IMT termed epithelioid inflammatory myofibroblastic sarcoma (EIMS).The tumors in IMT and EIMS consistently contain pro-inflammatory white blood cells and in most cases tumor cells that express highly abnormal oncogenic (cancer-causing) fusion proteins such as those that contain the active portion of anaplastic lymphoma kinase (ALK). It is not clear whether this inflammation, the genetic abnormalities, or both contribute to the development of IMT but drugs blocking the activities of the fusion proteins made by these genetic abnormalities may be useful in treating the disease. Signs and symptoms
IMT was regarded as a tumor that occurs in children or young adults and presented in the lung, mesentery, greater omentum or, less commonly, heart, liver, spleen, pancreas, colon, small intestine, spermatic cord, prostate, uterus, eye orbit, peripheral or central nervous system nerves, brain meninges, spinal cord, or other sites.