Histopathologic examination of the<unk> s in IMT generally reveals<unk>  spindle cell sheets in a myxoid background (i.e. a background matrix containing gelatinous mucopolysaccharides and non-sulfated glycosaminoglycans); the matrix also contains<unk>  cells, particularly plasma cells and lymphocytes occasionally mixed with eosinophils and neutrophils. The epithelioid<unk><unk>  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<unk>  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<unk> s 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.
Inflammatory myofibroblastic tumour
Reticulohistiocytoma
Plexiform angiomyxoid myofibroblastic tumor
Giant-cell reticulohistiocytoma
Adenomatoid tumor
Angiomatoid fibrous histiocytoma
Multinucleate cell angiohistiocytoma
Epithelioid sarcoma