Salivary glands - Mucoepidermoid carcinoma

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Salivary glands

Epithelial / myoepithelial tumors

Mucoepidermoid carcinoma

Reviewer: Adriana Handra-Luca, M.D. (see Reviewers page)
Revised: 29 January 2013, last major update September 2012
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.

General
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● Cords, sheets and clusters of mucous, squamous, intermediate and clear cells
● Most common malignant tumor in salivary glands
● Also most common radiation induced neoplasm

Clinical features
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● 2/3 occur in parotid gland; also in palate
● Wide age range, mean 49 years, range 15-86 years, no gender predominance
● Low grade: 15% recur, 5 year survival 90-98%, usually stage I
● High grade: 25% recur, 5 year survival 50-56%, deaths usually within first 5 years
● Note: significant grading disparity exists between pathologists (Am J Surg Pathol 2001;25:835)

AFIP point system:
● 2 points if <20% intracystic component
● 2 points if necrosis
● 2 points if neural invasion
● 3 points if 4+ mitotic figures/10 HPF
● 4 points if anaplasia
● Low grade if total score is 0-4 points, intermediate grade if 5-6 points, high grade if 7+ points

Prognostic factors
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● Poor prognostic factors: older age, male, submandibular gland, extraglandular extension, vascular invasion, necrosis, high mitotic rate, high histologic grade

Case reports
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● 55 year old man with low grade parotid tumor and dedifferentiation (Hum Pathol 2003;34:1068)

Treatment
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● Complete excision, possibly radiation therapy

Gross description
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● Low grade: well circumscribed with gray-white, mucin filled cysts

Micro description
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● Cords, sheets and clusters of mucous, squamous, intermediate and clear cells
● Low to high grade, although even high grade tumors lack marked nuclear atypia, frequent mitotic figures or extensive necrosis
● Occasional focal sebaceous cells, goblet-type cells, oncocytic change, inflammatory reaction to extravasated mucin or keratin
● No squamous cell carcinoma in situ
● Low grade: mucinous and intermediate cells with bland nuclei form glandular spaces
● High grade: solid and infiltrative growth pattern of atypical epidermoid and intermediate cells with cytoplasmic clearing and small number of mucinous cells; <20% intracystic component

Micro images
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Various images

Cases in children

Spindled morphology

H&E, CK7+ and CK20-

Cytology images
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Low grade with background mucin, two types of cells with bland nuclear features (squamoid with dense cytoplasm and glandular with vacuolated cytoplasm)

High grade with malignant squamous cells

Low grade and oncocytic tumors

Positive stains
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● Low grade: CK7, CK14, antimitochondrial antibodies

Electron microscopy description
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● Mixed luminal epithelial cells and myoepithelial cells

Electron microscopy images
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Spindled morphology

Molecular / cytogenetics description
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● Associated with t(11;19)(q14-21;p12-13)

Differential diagnosis
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● Adenosquamous carcinoma: has anaplastic nuclear features
● Metastatic carcinoma
● Necrotizing sialometaplasia
● Poorly differentiated adenocarcinoma

Oncocytic variant

General
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● Rare variant; oncocytic tumor cells are 60%+ of neoplasm
● First identified by Chomette (Ann Pathol 1982;2:29)
● <10% of all mucoepidermoid carcinomas
● Parotid, submandibular gland
● Female gender prevalence

Micro description
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● Frequently low grade, oncocytic cells of intermediate cell type, cystic pattern

Positive stains
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● PTAH (granular cytoplasmic staining, Am J Surg Pathol 1999;23:523), antimitochondrial antibodies, p63 (Am J Surg Pathol 2009;33:409)

Negative stains
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● Androgen receptor

Molecular / cytogenetics description
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● 71% MAML2 rearrangement (Hum Pathol 2011;42:2001, Hum Pathol 2011;42:2052)

Differential diagnosis
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● Acinic cell carcinoma
● Metastases may be similar to lung, kidney, breast metastases
● Oncocytic carcinoma
● Oncocytoma
● Pleomorphic adenoma

End of Salivary glands > Epithelial / myoepithelial tumors > Mucoepidermoid carcinoma

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