in IMT generally reveals myofibroblastic spindle cell sheets in a myxoid background (i.e. a background matrix containing gelatinous mucopolysaccharides and non-sulfated glycosaminoglycans); the matrix also contains inflammatory cells, particularly plasma cells and lymphocytes occasionally mixed with eosinophils and neutrophils. The epithelioid inflammatory myofibroblastic sarcoma subtype of IMT shows sheets of epithelioid to round cells within a myxoid (i.e. appears blue or purple compared to the normal red appearance of connective tissue when appropriately H&E stained and examined under the microscope), collagenous, or mixed myxoid-collagenous matrix, <5% spindle cells, and an inflammatory cell infiltrate that in most cases consists predominantly of neutrophils or, less often, small lymphocytes or eosinophils; plasma cells occur in only a minority of EIMS cases. The neoplastic cells in the tumors of 50% to 60% of IMT cases and 100% of EIMS cases express an ALK fusion protein. Other genetic abnormalities occur in these cells. Testing for the presence of the ALK fusion protein and other genetic abnormalities (see next section) can help diagnose IMT. Treatment Many sources recommend that localized IMT be treated with total resection of all tumorous tissues. Localized tumor recurrences may likewise be treated by total resection. There is little support for adding radiation or systemic chemotherapy to this regimen. Tumors that are not resectable, occur in inaccessible sites, are multifocal, or have metastasized are treated with aggressive therapeutic regimens. In one retrospective study, 59 patients (all <25 years old) with IMT where treated with surgery. 31 had no residual disease post-surgery; 4 of these patients had local relapses, 3 of whom were again treated surgically and 1 with surgery plus chemotherapy. Nineteen had microscopic residual disease post-surgery. Post-surgery, 6 of these patients were treated with high-dose corticosteroids; 5 with vinblastine + methotrexate chemotherapy; 3 with inhibitors of ALK; 2 with vinorelbine + low-dose cycloheximide or Ifosfamide-based chemotherapy; and 1 with cyclophosphamide + vinchristine + actinomycin D chemotherapy. Of these 19 patients, 4 had complete responses, 8 partial responses, 5 stable disease, and 2 progressive disease. Nine patients had macroscopic disease post-surgery; 5 of these patients received vincristine + methotrexate; 2 received ALK inhibitors; and 1 each received either high-dose corticosteroids or Ifosfamide-based chemotherapy. Of these 9 patients, none had complete responses; 6 had partial responses; 1 had steady disease; and 2 had progressive disease. There were no deaths among the 59 patients. The various drug regimens showed little differences in effectiveness although