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Mucoepidermoid carcinoma (view source)

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#redirect [[Salivary_glands#Mucoepidermoid_carcinoma]]
'''Mucoepidermoid carcinoma''', abbreviated ''MEC'', the is the most common malignant neoplasm of the [[salivary gland]].
 
==General==
*Most common malignant neoplasm of salivary gland in all age groups.<ref>URL: [http://path.upmc.edu/cases/case715/dx.html http://path.upmc.edu/cases/case715/dx.html]. Accessed on: 2 February 2012.</ref>
*Female:male ~= 3:2.
*Site: parotid > submandibular.
 
==Gross==
*Cystic or solid, usu. a mix of both.
 
==Microscopic==
Features:
*Architecture:<ref>URL: [http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/D2A001-PQ01-M.htm http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/D2A001-PQ01-M.htm]. Accessed on: 19 October 2010.</ref>
**Cystic (low grade).
**Solid (high grade).
*Mucous cells with abundant fluffy cytoplasm and large mucin vacuoles - '''key feature'''.
**Nucleus distorted by mucin vacuole.
**Mucous cell may be scarce - more difficult to diagnose.
*Epidermoid cells:
**Non-keratinized, polygonal squamoid cell with clear or oncocytic cytoplasm.
***Clear cells contain glycogen ([[PAS]] +ve, [[PAS-D]] -ve).
 
Notes:
*The classic description - composed of 3 cell types: epidermoid, intermediate, and mucin producing.<ref>{{Cite journal  | last1 = Lennerz | first1 = JK. | last2 = Perry | first2 = A. | last3 = Mills | first3 = JC. | last4 = Huettner | first4 = PC. | last5 = Pfeifer | first5 = JD. | title = Mucoepidermoid carcinoma of the cervix: another tumor with the t(11;19)-associated CRTC1-MAML2 gene fusion. | journal = Am J Surg Pathol | volume = 33 | issue = 6 | pages = 835-43 | month = Jun | year = 2009 | doi = 10.1097/PAS.0b013e318190cf5b | PMID = 19092631 }}</ref>
**"Intermediate cells" are described in textbooks. Weinreb thinks they are a pretty much a myth.<ref name=IW_10jan2011>IW. 10 January 2011.</ref>
*Mucin vacuoles may be rare; in a superficial glance -- it may mimic [[squamous cell carcinoma]].
*The thought of high-grade MEC should prompt consideration of squamous cell carcinoma.
 
===Images===
<gallery>
Image:Mucoepidermoid_carcinoma_%282%29_HE_stain.jpg | Mucoepidermoid carcinoma 2. (WC)
Image:Mucoepidermoid_carcinoma_%283%29_HE_stain.jpg | Mucoepidermoid carcinoma 3. (WC)
Image:Mucoepidermoid_carcinoma_-_2_-_intermed_mag.jpg | Mucoepidermoid carcinoma - 2 - intermed. mag. (WC/Nephron)
Image:Mucoepidermoid_carcinoma_-_2_-_high_mag.jpg | Mucoepidermoid carcinoma - 2 - high mag. (WC/Nephron)
Image:Mucoepidermoid_carcinoma_-_2a_-_very_high_mag.jpg | Mucoepidermoid carcinoma - 2 - very high mag. (WC/Nephron)
</gallery>
www:
*[http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/D2A001-PQ01-M.htm Mucoepidermoid carcinoma (ouhsc.edu)].
 
===Subtypes===
*Conventional.
*Oncocytic.
**Definition: composed of 50% oncocytes.
**Good outcome.<ref name=pmid18971778>{{cite journal |author=Weinreb I, Seethala RR, Perez-Ordoñez B, Chetty R, Hoschar AP, Hunt JL |title=Oncocytic mucoepidermoid carcinoma: clinicopathologic description in a series of 12 cases |journal=Am. J. Surg. Pathol. |volume=33 |issue=3 |pages=409–16 |year=2009 |month=March |pmid=18971778 |doi=10.1097/PAS.0b013e318184b36d |url=}}</ref>
*Clear cell.
*Unicystic (cystadenocarcinoma).
**Based on the gross. (???)
*Sclerosing MEC +/- eosinophilia.
**Rare.
 
===Grading===
General:
*Two competing system exist:
**AFIP.<ref name=pmid9529011>{{cite journal |author=Goode RK, Auclair PL, Ellis GL |title=Mucoepidermoid carcinoma of the major salivary glands: clinical and histopathologic analysis of 234 cases with evaluation of grading criteria |journal=Cancer |volume=82 |issue=7 |pages=1217–24 |year=1998 |month=April |pmid=9529011 |doi= |url=}}</ref>
**Brandwein.<ref name=pmid11420454>{{cite journal |author=Brandwein MS, Ivanov K, Wallace DI, ''et al.'' |title=Mucoepidermoid carcinoma: a clinicopathologic study of 80 patients with special reference to histological grading |journal=Am. J. Surg. Pathol. |volume=25 |issue=7 |pages=835–45 |year=2001 |month=July |pmid=11420454 |doi= |url=}}</ref>
 
Notes:
*Both systems have their pros and cons.
*Weinreb uses the AFIP system with a slight modification.
 
====AFIP====
#Low cystic content (<20%) - 2 points.
#[[Perineural invasion]] - 2 points.
#[[Necrosis]] - 3 points.
#Mitoses > 4 per 10 HPFs (HPF not defined in paper - see [[HPFitis]]) - 3 points.
#Anaplasia - 4 points.
 
Scoring:
*Low grade = 0-4 points.
*Intermediate grade = 5-6 points.
*High grade = 7+ points.
 
=====Weinreb modification=====
Weinreb looks for the following:
*Tumour invades in small nests/islands - 2 points.
**If applicable, the two points are added to the AFIP score.
**The tumour is graded using the AFIP (scoring) cut points -- see above.
 
Notes:
*It seems pointless to memorize this but it is occasionally asked on exams.
**How to remember: think of the Nottingham grading system (architecture, mitoses, nuclear grade) + necrosis + LVI.
 
==Stains==
Mucous cells:
*Alcian blue +ve.
*Mucicarcmine +ve.
 
==Molecular==
*t(11;19)(q21;p13) -- MECT1-MAML2 fusion.<ref name=pmid12539049>{{cite journal |author=Tonon G, Modi S, Wu L, ''et al.'' |title=t(11;19)(q21;p13) translocation in mucoepidermoid carcinoma creates a novel fusion product that disrupts a Notch signaling pathway |journal=Nat. Genet. |volume=33 |issue=2 |pages=208–13 |year=2003 |month=February |pmid=12539049 |doi=10.1038/ng1083 |url=}}</ref><ref name=pmid20588178>{{cite journal |author=Seethala RR, Dacic S, Cieply K, Kelly LM, Nikiforova MN |title=A reappraisal of the MECT1/MAML2 translocation in salivary mucoepidermoid carcinomas |journal=Am. J. Surg. Pathol. |volume=34 |issue=8 |pages=1106–21 |year=2010 |month=August |pmid=20588178 |doi=10.1097/PAS.0b013e3181de3021 |url=}}</ref>
**Present in ~65% of MECs.
**Presence assoc. with low-grade MEC (vs. high-grade MEC) & favourable prognosis.
**Not seen in tumours that are in the DDx of MEC.
 
==See also==
*[[Salivary glands]].
 
==References==
{{Reflist|2}}


[[Category:Diagnosis]]
[[Category:Diagnosis]]
[[Category:Salivary glands]]
Michael
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