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| ==Pleomorphic adenoma== | | ==Pleomorphic adenoma== |
| *Abbreviated ''PA''.
| | {{Main|Pleomorphic adenoma}} |
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| ===General===
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| Features:
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| *Very common - approx. 60% of parotid gland tumours.<ref name=Ref_HaNP295>{{Ref HaNP|295}}</ref>
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| *May transform into a malignant tumour.
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| **Other benign salivary gland tumours do not do this.
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| *Only benign childhood salivary gland tumour of significance.
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| ====Weinreb's dictums====
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| #Most common salivary tumour in all age groups.
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| #Seen in all sites (unlike other benign tumours).
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| #Recurrence and malignancy risk (unlike other benign salivary gland tumours).
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| #Any part of a tumour that looks like PA makes it a PA.
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| ===Gross===
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| *May be cartilaginous appearing.
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| Image:
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| *[http://screening.iarc.fr/atlasoral_detail.php?flag=1&lang=1&Id=C0100002&cat=C1 PA in situ (iarc.fr)].
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| ===Microscopic===
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| Features:<ref name=Ref_HaNP295>{{Ref HaNP|295}}</ref>
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| *Proliferation of myoepithelium and epithelium (ductal cells) in mesenchymal stroma.
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| **Cells in ducts = epithelial.
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| **Cells not in ducts = myoepithelial.<ref name=IW_10jan2011>IW. 10 January 2011.</ref>
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| *Mesenchymal stroma - '''important feature'''.
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| **May be any of following: [[myxoid stroma|myxoid]], mucochondroid, hyalinized, osseous, fatty.
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| ***[[chondromyxoid stroma|Chondroid]] = specific for PA; can diagnose PA without an epithelial (ductal) component if chondroid is present.
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| ***Myxoid = not specific for PA.
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| Notes:
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| *Mesenchymal stroma not required for diagnosis -- if >5% ducts.<ref name=IW_10jan2011>IW. 10 January 2011.</ref>
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| **No chondroid stroma ''and'' <5% ductal cells = '''[[myoepithelioma]]'''.
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| *Complete excision is often elusive; stating "completely excised" on a surgical pathology report is unwise.
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| *Look for, i.e. rule-out, poorly differentiated carcinoma: ''carcinoma ex pleomorphic adenoma''.
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| Memory device: '''MEC''' = '''m'''yoepithelium, '''e'''pithelium, '''c'''hondromyxoid stroma.
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| DDx:
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| *[[Myoepithelioma]].
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| *[[Carcinoma ex pleomorphic adenoma]].
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| *[[Epithelial-myoepithelial carcinoma]].
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| ====Images====
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| <gallery>
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| Image:Pleomorphic_adenoma_%281%29_parotid_gland.jpg | PA. (WC)
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| Image:Pleomorphic_adenoma_%282%29_parotid_gland.jpg | PA. (WC)
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| Image:Pleomorphic_adenoma_%283%29_parotid_gland.jpg | PA. (WC)
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| Image:Pleomorphic_adenoma_%284%29_parotid_gland.jpg | PA. (WC)
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| </gallery>
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| www:
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| *[http://www.webpathology.com/image.asp?n=7&Case=111 PA - myxoid stroma (webpathology.com)].
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| ===IHC===
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| *S-100 +ve, SMA +ve, GFAP +ve.
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| ==Myoepithelioma== | | ==Myoepithelioma== |