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Salivary glands

Epithelial / myoepithelial tumors

Adenoid cystic carcinoma


Reviewer: Adriana Handra-Luca, M.D. (see Reviewers page)
Revised: 1 February 2013, last major update September 2012
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.

General
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● Deceptively benign histologic appearance and cribriform, solid or tubular pattern similar to cylindroma of skin (Arch Pathol Lab Med 2011;135:511)
● Formerly called cylindroma
● Most common in submandibular, sublingual or minor salivary glands; also seen in nose, sinus, upper airway
● 22% of salivary gland malignancies

Clinical features
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● Occurs in 5th to 6th decades
● Male predominance
● Slow growing, indolent but aggressive
● Recurrences are frequent; often late and difficult to predict
● Rarely lymph node metastases
● 5 year survival is 60%, 10 year is 30%, 15 year is 15%
● Recurrence rates by pattern: solid (100%), cribriform (89%), tubular (59%)
● 15 year survival rates by pattern: solid (5%), cribriform (26%), tubular (39%)
● Better prognosis for tumors of palate or parotid gland; poorer prognosis for dedifferentiated, p53+ tumors

Treatment
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● Radical surgery regardless of tumor differentiation, radiotherapy

Gross description
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● Small, poorly circumscribed or encapsulated and infiltrative, 1 to 8 cm

Micro description
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● Cribriform, solid or tubular pattern similar to cylindroma of skin
● Small bland myoepithelial cells with scant cytoplasm and dark compact angular nuclei surround pseudoglandular spaces with PAS+ excess basement membrane material and mucin
● Peripheral perineurial invasion and small true glandular lumina
● No squamous differentiation, no extensive necrosis
Note: presence of pseudoglandular lumina, true glandular lumina and perineurial invasion is usually required for diagnosis
● Dedifferentiated tumors have irregular tumor islands composed of anaplastic cells with abundant cytoplasm and desmoplastic stroma

Grading:
● Low grade (grade 1): tubular and cribriform patterns
● Intermediate grade (grade 2): 30% to 70% solid
● High grade (grade 3): >70% (varies) solid

Micro images
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Classic tumor with cribriform and tubular structures


Various images as part of case history


Low grade to high grade


H&E, CK7 and CK20


H&E and CD117


Comparison with polymorphous low grade adenocarcinoma

Cytology images
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Fine needle aspirate: small cells with bland nuclear features forming a pseudoglandular space containing a homogeneous, metachromatically staining hyaline globule

Positive stains
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● Cells in ducts: keratin, CEA, alpha-1-antichymotrypsin, S100, CD117/c-kit (Mod Pathol 2003;16:1224)
● Cells around pseudoglandular spaces: S100, actin, variable keratin
● Dedifferentiated tumor: S100
● Also CK7+/CK20- (Mod Pathol 2004;17:407), beta-catenin, calponin, smooth muscle myosin heavy chain, maspin, metallothionein
● Also MYB (65%, Am J Surg Pathol 2011;35:92)
● EGFR, HER2, survivin associated with aggressive behavior (Hum Pathol 2012;43:921)
● Markers and histologic features: phospho-JUN (perineural invasion), p63 (basal / myoepithelial compartmentalization, Mod Pathol 2005;18:645)
● Markers and prognostic features: Ki67 (shorter overall survival), phospho-P38 (better overall survival), phospho-STAT3 (low/distant metastases)

Negative stains
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● Estrogen and progesterone receptor, usually androgen receptor (Am J Clin Pathol 2003;119:801)

Electron microscopy description
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● Pseudoglandular spaces, intercellular spaces, abundant basal lamina, true glandular lumina
● Cells are intercalated ducts, myoepithelial, secretory and reserve cells

Molecular / cytogenetics description
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● MYB-NFIB fusion transcript (86%, Mod Pathol 2011;24:1169)
● c-kit mutations common (Mod Pathol 2009;22:1296)
● Also Wnt pathway (Mod Pathol 2004;17:1475), 1p-32-36 deletion (Clin Cancer Res 2008;14:5181), PTEN deletion (Br J Cancer 2012;106:719), HER2 amplification

Differential diagnosis
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Basal cell adenocarcinoma
Basal cell adenoma: capsule present, no perineural invasion
Pleomorphic adenoma: has squamous metaplasia and mesenchyme-like areas, no invasion, no perineurial invasion; GFAP+ and CD57+ (Arch Pathol Lab Med 2007;131:1373)
Polymorphous low grade adenocarcinoma: very rare in major salivary glands, bland uniform cells, CD117 weak/negative (Mod Pathol 2002;15:687), negative for smooth muscle markers, metallothionein (Arch Pathol Lab Med 1999;123:801, Mod Pathol 2008;21:105)


Dedifferentiated tumors

General
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● Rare aggressive variant with death usually within 5 years of diagnosis (Am J Surg Pathol 1999;23:465, Mod Pathol 2003;16:1265)
● Dedifferentiated component either poorly differentiated adenocarcinoma or undifferentiated adenocarcinoma

Micro description
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● Nuclear enlargement and irregularity, high mitotic count, loss of biphasic ductal-myoepithelial differentiation, comedonecrosis, fibrocellular desmoplasia (Am J Surg Pathol 2007;31:1683)

Micro images
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Left-classic, right-dedifferentiated tumor


Poorly differentiated and undifferentiated tumor


HER2, p53, Rb, Ki-67

Positive stains
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● p53, cyclin D1, HER2

Molecular / cytogenetics description
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● C-MYC amplification (Arch Pathol Lab Med 2011;135:123)

End of Salivary glands > Epithelial / myoepithelial tumors > Adenoid cystic carcinoma


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