LGMFS tumors typically contain one or multiple nodules embedded in a grey-white whorled cut surface. They appear to be infiltrating adjacent structures/tissues in a minority of cases. Microscopic histopathologic views of hematoxylin and eosin stained tumor tissue show whorled and bundled, uniform, bland-appearing, slender fibroblastic spindle-shaped cells with elongated, tapered nuclei. The cells have scant cytoplasm and do not appear to be rapidly proliferating as defined by their<unk>  rate of mitosis. The spindle-shaped cells typically occur in an alternating fibrous and myxoid (i.e. more blue or purple compared to normal connective tissue because of excessive uptake of the hematoxylin stain) background. However, the tissues may contain sites dominated by epithelioid cells and other elements that resemble, or are indistinguishable from, sclerosing epithelioid fibrosarcoma. This hybrid pattern is more often seen in recurrent and metastatic<unk>  tumors, may progress to dominate the tissues, and may therefore warrant changing the diagnosis of<unk>  to sclerosing epithelioid fibrosarcoma. While not definitive, LGMFS tumors that are dominated with cells that have an undifferentiated or immature round-cell morphology may be more aggressive than tumors with the typical cell morphology. Immunohistochemical analyses of<unk>  tumors shows cells that express: MUC1 (also termed EMA), CD99, and/or bcl-2 proteins in some cases; CD34 and SMA proteins in rare cases; and S100, desmin, caldesmon, cytokeratin, and CD117 proteins in virtually no cases. However, MUC4 protein is express by the tumor cells of almost all<unk>  cases and therefore is commonly used as a sensitive and specific marker for<unk> . (Since a small subset of<unk>  tumors have been reported to consist of cells that are MUC4-negative, the diagnosis of<unk>  should not be absolutely dependent on finding MUC4-positive tumor cells.)
Low-grade fibromyxoid sarcoma
Solitary fibrous tumor
Undifferentiated pleomorphic sarcoma
Ossifying fibromyxoid tumour
Sclerosing epithelioid fibrosarcoma
Collagenous fibroma
Mammary-type myofibroblastoma
Aggressive fibromatosis