MUC4

Formalin-fixed, paraffin embedded tissue block or cell block, or 1 unstained charged slide for each test requested plus 3-4 additional unstained slides cut at 4 microns. Adequate space on each slide for control tissue is required.

MUC4 is a transmembranous glycoprotein, normally expressed in the cytoplasm of epithelial cells of endodermal origin, such as colon and lung. The MUC4 gene on chromosome 3 (3q29) is found to be upregulated in low-grade fibromyxoid sarcoma (LGFMS) with corresponding protein overexpression. MUC4 has thus become a sensitive and rather specific marker for LGFMS, and is negative in other histologic mimickers. MUC4 is also positive in sclerosing epitheliod fibrosarcoma, which has morphologic and molecular overlap with LGFMS, including the FUS gene re-arrangement.