Mucoepidermoid carcinoma

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Mucoepidermoid carcinoma
Diagnosis in short

Mucoepidermoid carcinoma. H&E stain.

LM mucous cells (abundant fluffy cytoplasm and large mucin vacuoles - nucleus distorted by mucin vacuole, cells may be scarce); epidermoid cells (non-keratinized, polygonal squamoid cell with clear or oncocytic cytoplasm); architecture - cystic (low grade) or solid (high grade)
LM DDx squamous cell carcinoma of the head and neck, adenosquamous carcinoma, pleomorphic adenoma
Stains mucous cells: alcian blue stain +ve, mucicarmine stain +ve
Molecular t(11;19)(q21;p13)
Gross solid, cystic or both
Site salivary gland, classically parotid gland

Signs mass lesion
Prevalence most common malignant salivary gland tumour, generally uncommon

Mucoepidermoid carcinoma, abbreviated MEC, the is the most common malignant neoplasm of the salivary gland.


  • Most common malignant neoplasm of salivary gland in all age groups.[1][2]
  • Female:male ~= 3:2.
  • Site: parotid > submandibular.


  • Cystic or solid, usually a mix of both.


  • May mimic a benign cystic lesion grossly.
  • Unicystic mucoepidermoid carcinoma is rare.[3]



  • Architecture:[4]
    • 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).


  • The classic description - composed of 3 cell types: epidermoid, intermediate, and mucin producing.[5]
    • "Intermediate cells" are described in textbooks. Weinreb thinks they are a pretty much a myth.[6]
  • 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.




Mucoepidermoid carcinoma of parotid, low grade Mucoepidermoid carcinoma of parotid, low grade Mucoepidermoid carcinoma of parotid, low grade Mucoepidermoid carcinoma of parotid, low grade

Low grade mucoepidermoid carcinoma in left parotid of 51 year old woman. A. Tumor shows blue squamoud differentiation with cystic dilatation. B This focus shows more obvious cyst formation. C. Squamous component with round to spindled cancer cells; note that currently squamous pearls and high grade squamous cancer elements render the tumor a squamous carcinoma, according to Barnes. D. Glandular cell component.


  • Conventional.
  • Oncocytic.
    • Definition: composed of 50% oncocytes.
    • Good outcome.[10]
  • Clear cell.
  • Unicystic (cystadenocarcinoma).
    • Based on the gross. (???)
  • Sclerosing MEC +/- eosinophilia.
    • Rare.



  • Two competing system exist:


  • Both systems have their pros and cons.
  • Weinreb uses the AFIP system with a slight modification.


  1. Low cystic component (<20%) - 2 points.
  2. Perineural invasion - 2 points.
  3. Necrosis - 3 points.
  4. Mitoses > 4 per 10 HPFs (HPF not defined in paper - see HPFitis) - 3 points.
  5. Anaplasia - 4 points.


  • 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.


  • 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.


Mucous cells:

  • Alcian blue +ve.
  • Mucicarmine +ve.



  • CK7 +ve.
  • CK20 -ve.
  • CEA +ve.[14]

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A. Lymph Node, Deep Lobe of Left Parotid Gland, Excision:
     - One lymph node NEGATIVE for malignancy (0/1).

B. Parotid Gland - Left Deep Lobe, Excision:
     -- Margins clear.
     -- Please see synoptic report.     


  • t(11;19)(q21;p13) -- MECT1-MAML2 fusion.[15][16]
    • 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


  1. URL: Accessed on: 2 February 2012.
  2. Bell, RB.; Dierks, EJ.; Homer, L.; Potter, BE. (Jul 2005). "Management and outcome of patients with malignant salivary gland tumors.". J Oral Maxillofac Surg 63 (7): 917-28. PMID 16003616.
  3. Qannam A, Bello IO, Al-Kindi M, Al-Hindi M (April 2013). "Unicystic mucoepidermoid carcinoma presenting as a salivary duct cyst". Int J Surg Pathol 21 (2): 181–5. doi:10.1177/1066896912454918. PMID 22843640.
  4. URL: Accessed on: 19 October 2010.
  5. Lennerz, JK.; Perry, A.; Mills, JC.; Huettner, PC.; Pfeifer, JD. (Jun 2009). "Mucoepidermoid carcinoma of the cervix: another tumor with the t(11;19)-associated CRTC1-MAML2 gene fusion.". Am J Surg Pathol 33 (6): 835-43. doi:10.1097/PAS.0b013e318190cf5b. PMID 19092631.
  6. IW. 10 January 2011.
  7. 7.0 7.1 Mokhtari, S.; Mokhtari, S. (2012). "Clinical features and differential diagnoses in laryngeal mucoepidermoid carcinoma.". Clin Med Insights Pathol 5: 1-6. doi:10.4137/CPath.S8435. PMID 22262946.
  8. Zanetti, D.; Renaldini, G.; Peretti, G.; Antonelli, AR.. "[Intra-parotid lymph node metastasis of malignant skin neoplasms of the head].". Acta Otorhinolaryngol Ital 9 (4): 381-90. PMID 2694753.
  9. Siddiqui, NH.; Wu, SJ. (Apr 2005). "Fine-needle aspiration biopsy of cystic pleomorphic adenoma with adnexa-like differentiation mimicking mucoepidermoid carcinoma: a case report.". Diagn Cytopathol 32 (4): 229-32. doi:10.1002/dc.20215. PMID 15754364.
  10. Weinreb I, Seethala RR, Perez-Ordoñez B, Chetty R, Hoschar AP, Hunt JL (March 2009). "Oncocytic mucoepidermoid carcinoma: clinicopathologic description in a series of 12 cases". Am. J. Surg. Pathol. 33 (3): 409–16. doi:10.1097/PAS.0b013e318184b36d. PMID 18971778.
  11. Goode RK, Auclair PL, Ellis GL (April 1998). "Mucoepidermoid carcinoma of the major salivary glands: clinical and histopathologic analysis of 234 cases with evaluation of grading criteria". Cancer 82 (7): 1217–24. PMID 9529011.
  12. Brandwein MS, Ivanov K, Wallace DI, et al. (July 2001). "Mucoepidermoid carcinoma: a clinicopathologic study of 80 patients with special reference to histological grading". Am. J. Surg. Pathol. 25 (7): 835–45. PMID 11420454.
  13. Jastrzebski, A.; Brownstein, S.; Jordan, DR.; Gilberg, SM. (Apr 2012). "Histochemical analysis and immunohistochemical profile of mucoepidermoid carcinoma of the conjunctiva.". Saudi J Ophthalmol 26 (2): 205-10. doi:10.1016/j.sjopt.2012.01.004. PMID 23960993.
  14. Hassanin, MB.; Ghosh, L.; Das, AK.; Waterhouse, JP. (May 1989). "Immunohistochemical and fluorescent microscopic study of histogenesis of salivary mucoepidermoid carcinoma.". J Oral Pathol Med 18 (5): 291-8. PMID 2475619.
  15. Tonon G, Modi S, Wu L, et al. (February 2003). "t(11;19)(q21;p13) translocation in mucoepidermoid carcinoma creates a novel fusion product that disrupts a Notch signaling pathway". Nat. Genet. 33 (2): 208–13. doi:10.1038/ng1083. PMID 12539049.
  16. Seethala RR, Dacic S, Cieply K, Kelly LM, Nikiforova MN (August 2010). "A reappraisal of the MECT1/MAML2 translocation in salivary mucoepidermoid carcinomas". Am. J. Surg. Pathol. 34 (8): 1106–21. doi:10.1097/PAS.0b013e3181de3021. PMID 20588178.