The myoepithelial immunophenotype in 135 benign and malignant salivary gland tumors other than pleomorphic adenoma.
BACKGROUND
We have previously studied the immunoreactivity of 3 novel smooth muscle-specific proteins, alpha-smooth muscle actin, smooth muscle myosin heavy chains, and calponin, to assess myoepithelial differentiation in pleomorphic adenomas.


OBJECTIVE
To further expand our knowledge of myoepithelial differentiation in other benign and malignant salivary gland tumors.


METHODS
Formalin-fixed paraffin sections of 135 salivary gland tumors with associated normal glands were stained with monoclonal antibodies using the avidin-biotin complex immunoperoxidase method and enzymatic and microwave heat-induced epitope retrieval.


RESULTS
In adenoid cystic carcinomas and epithelial-myoepithelial carcinomas, all 3 markers exclusively highlighted the myoepithelial cell components and the epithelial cells were entirely negative. No immunostaining was detected in canalicular adenomas, oncocytomas, Warthin tumors, acinic cell carcinomas, mucoepidermoid carcinomas, squamous cell carcinomas, and polymorphous low-grade adenocarcinomas. Salivary duct carcinomas and adenocarcinomas, not otherwise specified had a distinctive pattern of uniform periductal staining of reactive myofibroblastic cells, and in salivary duct carcinomas some ducts retained a peripheral immunoreactive myoepithelial cell layer.


CONCLUSIONS
Immunoreactivity for these 3 smooth muscle-specific proteins confirms the known neoplastic myoepithelial component of adenoid cystic carcinomas and epithelial-myoepithelial carcinomas. The consistently positive staining pattern in adenoid cystic carcinomas may be diagnostically useful in discriminating histologically similar but consistently negative polymorphous low-grade adenocarcinomas. Periductal linear staining in adenocarcinoma, not otherwise specified and salivary duct carcinomas is distinctive and appears to represent a tight cuff of myofibroblasts associated with the infiltrating glands.
Prasad
A R
AR
Henry Ford Hospital, Detroit, MI 48202, USA.
Savera
A T
AT
Gown
A M
AM
Zarbo
R J
RJ
D000199:Actins / Q000378:metabolism*; D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D000235:Adenolymphoma / Q000378:metabolism / Q000473:pathology; D000236:Adenoma / Q000378:metabolism / Q000473:pathology; D018249:Adenoma, Oxyphilic / Q000378:metabolism / Q000473:pathology; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D018267:Carcinoma, Acinar Cell / Q000378:metabolism / Q000473:pathology; D003528:Carcinoma, Adenoid Cystic / Q000378:metabolism / Q000473:pathology; D018277:Carcinoma, Mucoepidermoid / Q000378:metabolism / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology; D002454:Cell Differentiation; D006801:Humans; D007150:Immunohistochemistry; D008840:Microfilament Proteins; D009124:Muscle Proteins / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism*; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D018987:Salivary Ducts / Q000378:metabolism / Q000473:pathology; D012468:Salivary Gland Neoplasms / Q000378:metabolism* / Q000473:pathology; D012469:Salivary Glands / Q000166:cytology / Q000378:metabolism; D000096985:Calponins
D000199:Actins; D002135:Calcium-Binding Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D018995:Myosin Heavy Chains; D000096985:Calponins