• All IHC stains will include a positive control tissue

• SMMSHC-1 will stain myoepithelial cells of ducts and acini in normal breast lobules. It will also react with vascular smooth muscle
• SMMSHC-1 reacts with the intact myoepithelial cell layer present in benign and in situ breast lesions. It is useful in distinguishing benign breast and DCIS from invasive tumors of the breast
• Rarely, reactivity is seen with myofibroblasts in desmoplastic stroma of invasive carcinoma (5 of 70 cases). When positive, only rare stromal cells were immunostained. ¹
• Myoepithelial layers in complex sclerosing lesions and papillomas stain positively along papillary fronds with SMMSHC-1 but no myoepithelial immunostaining along the papillary fronds has been observed in intracystic papillary carcinoma
• SMMSHC-1 has been reported to label neoplastic myoepithelium of pleomorphic adenomas of the salivary gland ²
• It is not yet known how SMMSHC-1 reacts in micro-glandular adenosis. Micro-glandular adenosis is a benign lesion of the breast composed of a single layer of epithelial cells, which has been reported to be devoid of a surrounding myoepithelial layer (i.e. MSA negative).

Submit a formalin-fixed, paraffin embedded tissue block

Formalin-fixed, paraffin embedded (FFPE) tissue block

FFPE tissue section mounted on a charged, unstained slide

Ambient (preferred)

• Unlabeled/mislabeled block
• Insufficient tissue
• Slides broken beyond repair

Immunohistochemical staining and microscopic examination

If requested, an interpretive report will be provided

Specifications

• Antibody recognizes a cytoplasmic protein (SM-MHC, smooth muscle myosin heavy chain) which is a major component of the contractile apparatus in smooth muscle cells
• 2 isoforms of SM-MHC exist: SM1 (204 kd) and SM2 (200 kd). Both isoforms are expressed in smooth muscle cells (markers of terminal smooth muscle differentiation)

Staining pattern

• Cytoplasmic based

References

1. Wang et al: Antibodies to Novel Myoepithelium - Associated Proteins Distinguish Benign Lesions and Carcinoma in Situ From Invasive Carcinoma of the Breast; Applied Immunohistochemistry; 5(3):141-151, 1997.
2. Data Sheet, DAKO.