Pleomorphic adenoma: Difference between revisions

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#redirect [[Salivary_glands#Pleomorphic_adenoma]]
{{ Infobox diagnosis
| Name      = {{PAGENAME}}
| Image      = Pleomorphic_adenoma_%281%29_parotid_gland.jpg
| Width      =
| Caption    = Pleomorphic adenoma. [[H&E stain]]. (WC/KGH)
| Synonyms    = benign mixed tumour
| Micro      = proliferation of myoepithelium in a mesenchymal stroma +/- epithelium; cells in ducts = epithelial, cells not in ducts = myoepithelial, mesenchymal stroma = [[chondromyxoid stroma|chondroid]] stroma (specific), others (require epithelium) mucochondroid, hyalinized, osseous, fatty, myxoid
| Subtypes  =
| LMDDx      = [[myoepithelioma]], [[carcinoma ex pleomorphic adenoma]], [[epithelial-myoepithelial carcinoma]], [[polymorphous low-grade adenocarcinoma]], [[adenoid cystic carcinoma]]
| Stains    =
| IHC        = S-100 +ve, SMA +ve, GFAP +ve
| EM        =
| Molecular  =
| IF        =
| Gross      =
| Grossing  =
| Site      = [[salivary gland]] - usu. parotid gland, [[oral cavity]], other sites
| Assdx      =
| Syndromes  =
| Clinicalhx =
| Signs      = mass lesion
| Symptoms  =
| Prevalence = common
| Bloodwork  =
| Rads      =
| Endoscopy  =
| Prognosis  = benign
| Other      =
| ClinDDx    = other [[salivary gland]] tumours
}}
'''Pleomorphic adenoma''', abbreviated '''PA''', is a very common benign [[salivary gland]] tumour.
 
It is also known as '''benign mixed tumour'''.<ref>URL: [http://radiopaedia.org/articles/pleomorphic-adenoma-of-the-salivary-glands http://radiopaedia.org/articles/pleomorphic-adenoma-of-the-salivary-glands]. Accessed on: 30 March 2016.</ref><ref name=pmid19926180>{{Cite journal  | last1 = Lingam | first1 = RK. | last2 = Daghir | first2 = AA. | last3 = Nigar | first3 = E. | last4 = Abbas | first4 = SA. | last5 = Kumar | first5 = M. | title = Pleomorphic adenoma (benign mixed tumour) of the salivary glands: its diverse clinical, radiological, and histopathological presentation. | journal = Br J Oral Maxillofac Surg | volume = 49 | issue = 1 | pages = 14-20 | month = Jan | year = 2011 | doi = 10.1016/j.bjoms.2009.09.014 | PMID = 19926180 }}</ref>
==General==
Features:
*Very common - approx. 60% of parotid gland tumours.<ref name=Ref_HaNP295>{{Ref HaNP|295}}</ref>
*May transform into a malignant tumour.
**Other benign salivary gland tumours do not do this.
*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==
*May have [[cartilage|cartilaginous]] appearance.
*Typically well-circumscribed.
 
Image:
*[http://screening.iarc.fr/atlasoral_detail.php?flag=1&lang=1&Id=C0100002&cat=C1 PA in situ (iarc.fr)].
 
==Microscopic==
Features:<ref name=Ref_HaNP295>{{Ref HaNP|295}}</ref>
*Proliferation of myoepithelium and epithelium (ductal cells) in mesenchymal stroma.
**Cells in ducts = epithelial.
**Cells not in ducts = myoepithelial.<ref name=IW_10jan2011>Weinreb I. 10 January 2011.</ref>
*Mesenchymal stroma - '''important feature'''.
**May be any of following: [[myxoid stroma|myxoid]], mucochondroid, hyalinized, osseous, fatty.
***[[chondromyxoid stroma|Chondroid]] = specific for PA; can diagnose PA without an epithelial (ductal) component if chondroid is present.
***Myxoid = not specific for PA.
 
Notes:
*Mesenchymal stroma not required for diagnosis -- if >5% ducts.<ref name=IW_10jan2011>Weinreb I. 10 January 2011.</ref>
**No chondroid stroma ''and'' <5% ductal cells = '''[[myoepithelioma]]'''.
*Look for, i.e. rule-out, poorly differentiated carcinoma: ''carcinoma ex pleomorphic adenoma''.
 
Memory device: '''MEC''' = '''m'''yoepithelium, '''e'''pithelium, '''c'''hondromyxoid stroma.
 
DDx:
*[[Myoepithelioma]].
*[[Carcinoma ex pleomorphic adenoma]].
*[[Epithelial-myoepithelial carcinoma]].
*[[Polymorphous low-grade adenocarcinoma]].
*[[Adenoid cystic carcinoma]].
*[[Mucoepidermoid carcinoma]] - occasionally.<ref name=pmid15754364>{{Cite journal  | last1 = Siddiqui | first1 = NH. | last2 = Wu | first2 = SJ. | title = Fine-needle aspiration biopsy of cystic pleomorphic adenoma with adnexa-like differentiation mimicking mucoepidermoid carcinoma: a case report. | journal = Diagn Cytopathol | volume = 32 | issue = 4 | pages = 229-32 | month = Apr | year = 2005 | doi = 10.1002/dc.20215 | PMID = 15754364 }}</ref>
 
===Images===
====Case 1====
<gallery>
Image:Pleomorphic_adenoma_%281%29_parotid_gland.jpg | PA. (WC/KGH)
Image:Pleomorphic_adenoma_%282%29_parotid_gland.jpg | PA. (WC/KGH)
Image:Pleomorphic_adenoma_%283%29_parotid_gland.jpg | PA. (WC/KGH)
Image:Pleomorphic_adenoma_%284%29_parotid_gland.jpg | PA. (WC/KGH)
</gallery>
====Case 2====
<gallery>
Image: Pleomorphic adenoma - cell block -- intermed mag.jpg | PA - intermed. mag. (WC)
Image: Pleomorphic adenoma - cell block -- high mag.jpg | PA - intermed. mag. (WC)
Image: Pleomorphic adenoma - cell block -- very high mag.jpg | PA - intermed. mag. (WC)
</gallery>
====www====
*[http://www.webpathology.com/image.asp?n=7&Case=111 PA - myxoid stroma (webpathology.com)].
 
==IHC==
*S-100 +ve.
*SMA +ve.
*GFAP +ve.
 
==Sign out==
<pre>
Left Partial Parotid, Partial Parotidectomy:
- Pleomorphic adenoma.
- Three benign lymph nodes.
- NEGATIVE for malignancy.
</pre>
 
===Block letters===
<pre>
PAROTID GLAND MASS, RIGHT, EXCISION:
- PLEOMORPHIC ADENOMA.
- FOUR BENIGN LYMPH NODES.
- NEGATIVE FOR MALIGNANCY.
</pre>
 
Note:
*Complete excision is often elusive; stating "completely excised" on a surgical pathology report is unwise.<ref name=IW_10jan2011>Weinreb I. 10 January 2011.</ref>
 
===Micro===
The sections show a lesion with spindled (myoepithelial) cells and an epithelial component, on a background of a chondromyxoid stroma. The lesion is encapsulated by a thin layer of fibrous tissue.  No nuclear atypia is apparent. Mitotic activity is not identified.
 
Unremarkable parotid gland and lymph nodes are present.
 
====Alternate====
The sections show a lesion with spindled (myoepithelial) cells and an epithelial component,
on a background of a myxoid stroma. The lesion is mostly encapsulated by a thin layer of
fibrous tissue. A small focus of macrophages is present. Significant nuclear atypia is
not identified.  Mitotic activity is not apparent.  Unremarkable parotid gland and a
morphologically benign lymph node are present. Ink is seen on the tumour.
 
====Biopsy====
The sections show a lesion with spindled (myoepithelial) cells and an epithelial component, on a background of a chondromyxoid stroma. No nuclear atypia is apparent. Mitotic activity is not identified.
 
<pre>
The tumour stains as follows:
POSITIVE: CK7, S-100, SMA, GFAP (patchy).
NEGATIVE: (none).
PROLIFERATION (Ki-67): <2%.
</pre>
 
==See also==
*[[Salivary glands]].
*[[Salivary gland cytopathology]].
 
==References==
{{Reflist|2}}
 


[[Category:Diagnosis]]
[[Category:Diagnosis]]
[[Category:Salivary gland]]
Retrieved from "https://librepathology.org/wiki/Pleomorphic_adenoma"