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Salivary glands

Epithelial / myoepithelial tumors

Clear cell carcinoma


Reviewer: Adriana Handra-Luca, M.D. (see Reviewers page)
Revised: 26 January 2013, last major update September 2012
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.

General
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● First described in 1975 by Mohamed (Cancer 1975;36:1057) and in 1983 by Chen (Hum Pathol 1983;14:91)
● <100 cases reported to date
● May be a type of squamous cell carcinoma (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:399)
● Varies from monomorphic tumor (with or without hyalinizing stroma) with squamous, glandular or no differentiation to monomorphic clear cell myoepithelial carcinoma to bimorphic epithelial-myoepithelial carcinoma (adenomyoepithelioma, glycogen rich adenoma and glycogen rich adenocarcinoma)

Clinical features
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● Usually adult women with painless mass; 91% in minor salivary gland tumors (palate, base of the tongue)
● 1% of intraoral minor salivary gland tumors; also occur in major salivary glands
● Usually age 30+ years
● May occur in pleomorphic adenoma (Acta Cytol 2006;50:687), be associated with HIV (Int J Oral Maxillofac Surg 2011;40:760)
● Low grade but also aggressive
● 19% lymph node positive, 8% distant metastases, 3% have death due to disease

Case reports
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● 50 year old woman with intra-oral minor salivary gland tumor (Ann Acad Med Singapore 2007;36:857)

Treatment
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● Surgical excision with adequate margins, radiotherapy (possibly)
● Treat recurrences aggressively (Arch Pathol Lab Med 2002;126:676)

Gross description
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● Infiltrating, scar-like

Micro description
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● Trabeculae, cords, islands or nests of monomorphic clear cells
● Also cells with eosinophilic and granular cytoplasm
● Infiltrative borders
● Variable atypia
● No/rare mitotic figures
● No myoepithelial differentiation

Micro images
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Various images

Positive stains
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● PAS diastase sensitive (glycogen), cytokeratin (high molecular weight), CEA, EMA
● Also S100 (varied), NSE, alpha-1-antichymotrypsin, MAM3, MAM6 (Anticancer Res 1994;14:825), CK7, CK17, CK19 (Virchows Arch A Pathol Anat Histopathol 1988;412:515)

Negative stains
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● Mucin, smooth muscle actin, calponin, vimentin, CK10/13, CK20

Electron microscopy description
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● Abundant glycogen (Ultrastruct Pathol 1996;20:519), desmosomes, peripheral tonofilaments, squamoid differentiation, prominent interdigitating microvilli without actin myofilaments or dense bodies
● No lipid, no zymogen granules, no true ductal lumina, no myoepithelial differentation

Electron microscopy images
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Various images

Differential diagnosis
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Acinic cell carcinoma: negative for glycogen, fat and mucin
● Clear cell change in oncocytic tumors
Epithelial-myoepithelial carcinoma
● Metastatic renal cell carcinoma: positive for RCC, glycogen, vimentin and CD10, negative for high molecular weight cytokeratin, CEA, S100, muscle markers; abundant lipid but no squamoid differentiation by EM (Am J Surg Pathol 1999;23:1532)
Mucoepidermoid carcinoma: positive for mucin
Myoepithelioma: also positive for glycogen
● Sebaceous carcinoma
● Sebaceous neoplasms: positive for fat


Hyalinizing subtype

General
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● Nests of clear cells surrounded by hyalinized bands with foci of myxohyaline stroma; first described in 1994 by Milchgrub
● 1% of intraoral salivary gland tumors
● Usually women
● Often intraoral salivary glands at base of tongue or palate; also parotid, minor salivary glands of nasopharynx and jaw
● Low grade malignancies with 15% nodal metastases and possible late recurrence
● Must exclude other clear cell tumors (ORL J Otorhinolaryngol Relat Spec 1999;61:48)

Case reports
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● 36 year old woman (J Oral Maxillofac Pathol 2011;15:335)
● Adult woman with aggressive tumor of tongue (Oral Oncol 2004;40:348)

Treatment
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● Surgery, radiotherapy

Clinical images
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36 year old woman

Micro description
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● Solid masses, nests, infiltrating cords or single file clear cells composed of glycogen with mild atypia or eosinophilic cytoplasm
● Hyalinized or rarely myxoid stroma (Head Neck Pathol 2009;3:179), cystic degeneration, necrosis, mitotic foci, anaplasia

Micro images
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Clear to eosinophilic cytoplasm, EMA+, negative for muscle markers




Various images


36 year old woman

Cytology description
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● Cohesive small and large epithelial cells with sharp outlines, focal nuclear overlapping, small nucleoli (Diagn Cytopathol 2000;23:333)

Positive stains
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● PAS, EMA, CK5, 6, 7, 8, 14, 17, 18 (Am J Surg Pathol 1994;18:74, Eur J Histochem 2008;52:251)
● Also collagen 1, 3, 4, tenascin, fibronectin (Oral Oncol 2002;38:364)

Negative stains
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● CK20, vimentin, S100, muscle specific actin, smooth muscle actin, calponin, mucin, desmin

Molecular / cytogenetics description
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● EWSR1-ATF1 rearrangement (Genes Chromosomes Cancer 2011;50:559)

End of Salivary glands > Epithelial / myoepithelial tumors > Clear cell carcinoma


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