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==Pleomorphic adenoma== | ==Pleomorphic adenoma== | ||
*Abbreviated ''PA''. | |||
===General=== | ===General=== | ||
Features: | Features: | ||
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**Other benign salivary gland tumours do not do this. | **Other benign salivary gland tumours do not do this. | ||
*Only benign childhood salivary gland tumour of significance. | *Only benign childhood salivary gland tumour of significance. | ||
====Weinreb's dictums==== | |||
#Most common salivary tumour in all age groups. | |||
#Seen in all sites (unlike other benign tumours). | |||
#Recurrence and malignancy risk (unlike other benign salivary gland tumours). | |||
#Any part of a tumour that looks like PA makes it a PA. | |||
===Gross=== | ===Gross=== | ||
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===Microscopic=== | ===Microscopic=== | ||
Features:<ref name=Ref_HaNP295>{{Ref HaNP|295}}</ref> | Features:<ref name=Ref_HaNP295>{{Ref HaNP|295}}</ref> | ||
*Proliferation of myoepithelium and epithelium in mesenchymal stroma. | *Proliferation of myoepithelium and epithelium (ductal cells) in mesenchymal stroma. | ||
*Mesenchymal stroma - | **Cells in ducts = epithelial. | ||
**Cells not in ducts = myoepithelial.<ref>IW. 10 January 2011.</ref> | |||
*Mesenchymal stroma - '''important feature'''. | |||
**May be any of following: myxoid, mucochondroid, hyalinized, osseous, fatty. | **May be any of following: myxoid, mucochondroid, hyalinized, osseous, fatty. | ||
***Chondroid = specific for PA; can diagnose PA without an epithelial (ductal) component if chondroid is present. | |||
***Myxoid = not specific for PA. | |||
Notes: | Notes: | ||
*Mesenchymal stroma not required for diagnosis -- if >5% ducts.<ref>IW. 10 January 2011.</ref> | |||
**No chondroid stroma ''and'' <5% ductal cells = '''myoepithelioma'''. | |||
*Complete excision is often elusive; stating "completely excised" on a surgical pathology report is unwise. | *Complete excision is often elusive; stating "completely excised" on a surgical pathology report is unwise. | ||
*Look for, i.e. rule-out, poorly differentiated carcinoma: ''carcinoma ex pleomorphic adenoma''. | *Look for, i.e. rule-out, poorly differentiated carcinoma: ''carcinoma ex pleomorphic adenoma''. | ||
Memory device: '''MEC''' = '''m'''yoepithelium, '''e'''pithelium, '''c'''hondromyxoid stroma. | |||
===IHC=== | ===IHC=== |
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