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)
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.

General

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

Gross

  • Cystic or solid, usu. a mix of both.

Microscopic

Features:

  • Architecture:[2]
    • 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.[3]
    • "Intermediate cells" are described in textbooks. Weinreb thinks they are a pretty much a myth.[4]
  • 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

  • Mucoepidermoid carcinoma 2. (WC)

  • Mucoepidermoid carcinoma 3. (WC)

  • Mucoepidermoid carcinoma - 2 - intermed. mag. (WC/Nephron)

  • Mucoepidermoid carcinoma - 2 - high mag. (WC/Nephron)

  • Mucoepidermoid carcinoma - 2 - very high mag. (WC/Nephron)

www:

Subtypes

  • Conventional.
  • Oncocytic.
    • Definition: composed of 50% oncocytes.
    • Good outcome.[5]
  • Clear cell.
  • Unicystic (cystadenocarcinoma).
    • Based on the gross. (???)
  • Sclerosing MEC +/- eosinophilia.
    • Rare.

Grading

General:

  • Two competing system exist:

Notes:

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

AFIP

  1. Low cystic content (<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.

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.
  • Mucicarmine +ve.

Molecular

  • t(11;19)(q21;p13) -- MECT1-MAML2 fusion.[8][9]
    • 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

References

  1. ↑ URL: http://path.upmc.edu/cases/case715/dx.html. Accessed on: 2 February 2012.
  2. ↑ URL: http://moon.ouhsc.edu/kfung/jty1/opaq/PathQuiz/D2A001-PQ01-M.htm. Accessed on: 19 October 2010.
  3. ↑ 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.
  4. ↑ IW. 10 January 2011.
  5. ↑ 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.
  6. ↑ 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.
  7. ↑ 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.
  8. ↑ 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.
  9. ↑ 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.
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