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Salivary glands

Epithelial / myoepithelial tumors

Sebaceous adenoma / lymphadenoma


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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● Rare benign tumor with nests and islands of bland epithelium composed in part of sebaceous elements, with lymphoid stroma
● Called sebaceous lymphadenoma if lymphoid stroma is prominent
● Also called benign lymphoepithelial cyst with sebaceous differentiation

Clinical features
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● 0.1% of salivary gland neoplasms, <0.5% of salivary adenomas
● Over 90% occur in or near the parotid gland or in minor salivary glands
● May arise from salivary duct inclusions within parotid lymph node, similar to Warthin’s tumor (Am J Clin Pathol 1980;74:683)
● Fine needle aspiration cytology identifies a benign process, but usually not diagnosed prior to excision (Acta Otorhinolaryngol Ital 2007;27:144)

Case reports
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● 53 year old woman with progressively enlarging, painless parotid mass (University of Pittsburgh Case of Month 281)
● 57 year old man with neck mass (Arch Pathol Lab Med 2005;129:e171)
● 67 year old woman with parotid mass (Acta Otorhinolaryngol Ital 2007;27:147)
● 68 year old woman with synchromous squamous cell carcinoma (World J Surg Oncol 2003;1:30)
● 86 year old man with stable parotid mass (Case of the Week #103)
● Benign tumor with transition to sebaceous adenocarcinoma (Eur Arch Otorhinolaryngol 2006;263:940)

Treatment
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● Excision is curative, no/rare recurrences, rare malignant transformation (Eur Arch Otorhinolaryngol 2006;263:940)

Gross description
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● Solid or cystic, well circumscribed, tan-yellow mass, up to 3 cm, with variable encapsulation

Gross images
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Case of week #103: large nodule is sebaceous adenoma, small nodule on left is oncocytoma


Parotid gland masses


Various images


With synchronous squamous cell carcinoma

Micro description
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● Benign, encapsulated, solid and cystic (Mod Pathol 2012;25:26)
● Nests and islands of benign squamous cells, often lining a cyst; epithelial nests have focal sebaceous differentiation
● Background is prominent lymphoid infiltrate, often with germinal centers
● May be associated foreign body reaction, histiocytes, oncocytic change
● Rarely malignant change to sebaceous carcinoma
● May be combined / hybrid / synchronous tumors with Warthin tumor, acinic cell carcinoma, adenoid cystic carcinoma, squamous cell carcinoma (Eur J Cancer B Oral Oncol 1996;32B:251, Pathol Res Pract 1993;189:577, J Oral Surg 1979;37:826)

Micro images
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Case of week #103: large nodule


Benign parotid mass with sebaceous features and lymphoid stroma


Parotid gland mass


Various images


Malignant transformation

Cytology description
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● Mixed population of large and small lymphocytes, plasma cells and occasional tingible body macrophages
● 3 dimensional, cohesive aggregates of epithelial cells, often with cytoplasmic vacuoles characteristic of sebaceous differentiation, surrounded by layers of basaloid cells (Acta Cytol 2004;48:551, Acta Cytol 2004;48:551)

Cytology images
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Diff Quik touch prep

Positive stains
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● p63, 34betaE12, CK5/6, CK18, CK7

Negative stains
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● EBV, HPV, HHV8

Molecular / cytogenetics description
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● May have trisomy 9 (Oncol Rep 1994;1:561)

Differential diagnosis
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Low grade mucoepidermoid carcinoma: epithelial islands, ducts and cysts tend to be haphazardly distributed with variable shapes and sizes; usually infiltration of connective tissue or parenchyma; cells have some atypia, cells are mucin+
● Normal sebaceous glands: present in 10% of parotid glands but no mass
Warthin’s tumor: prominent cysts and lymphoid stroma, cysts have bilayered oncocytic epithelium

End of Salivary glands > Epithelial / myoepithelial tumors > Sebaceous adenoma / lymphadenoma


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