Caldesmon

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.

Caldesmon is a developmentally regulated protein involved in smooth muscle and non-muscle tissue contraction. The heavy-caldesmon is predominantly expressed in smooth muscle tissue and can be used as a smooth muscle marker. It is helpful in the distinction of smooth muscle neoplasm (positive) from myofibroblastic proliferation, such as nodular fasciitis (generally negative). It is also generally negative in endometrial stromal tumors.