Alternate Test Names:
Smooth muscle myosin heavy chain

Methodology: IHC

Clinical Significance:
Identifies: A component of smooth muscle myosin, a protein expressed in cells and tumors showing smooth muscle or myoepithelial differentiation. May also be expressed in myofibroblasts. Most commonly employed to distinguish invasive v. in situ breast carcinoma, usually in conjunction with at least one other myoepithelial marker, e.g., p63.

Subcellular Localization: Cytoplasmic

Organ: Breast

Disease State: Breast Cancer

CPT Code(s): 88342 or 88341 (reference only; CPTs may vary)

Turnaround Time: Within 1-2 business days of receipt

Schedule: Monday - Friday

Specimen Requirements:
• Formalin-fixed, paraffin-embedded (FFPE) tissue block or cell block - OR -
• 1 unstained slide for each test requested plus 3-4 additional unstained slides cut at 4µm