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Soft Tissue Tumors Part 3
Muscle, Vascular, Nerve, Other
Myoepithelial carcinoma of soft tissue
Author: Nat Pernick, M.D, PathologyOutlines.com, Inc.
Revised: 15 September 2009, last major update - September 2009
Copyright: (c) 2002-2009, PathologyOutlines.com, Inc.
Definition
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● Rare tumor with myoepithelial elements but no ductal differentiation
● May be related to parachordoma or mixed tumor
Epidemiology
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● Equal gender frequency, occurs in all ages, but mean age 38 years
● 20% occur in children
Sites
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● Extremities, limb girdles, viscera, head & neck
Case reports
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● 17 year old boy with forearm tumor and lung metastases (Pathol Int 2005;55:510)
● 30 year old man with leg tumor (Indian J Pathol Microbiol 2007;50:761)
● 82 year old woman with 16 cm gluteal tumor (Cancer Genet Cytogenet 2008;183:121)
Treatment and prognosis
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● In children, 53% had a local recurrence, 52% had metastases, 43% died of disease at median 9 months after diagnosis (Am J Surg Pathol 2007;31:1813)
● In all ages, 42% recurred locally, 32% metastasized (Am J Surg Pathol 2003;27:1183)
Gross description
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● Mean 5 cm, often well circumscribed
Micro description
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● Nests, cords and sheets of epithelioid, clear, spindle or plasmacytoid cells in hyalinized or chondromyxoid stroma
● Epithelioid cells predominate in 93% of childhood cases
● Moderate to severe atypia due to coarse chromatin, prominent nucleoli, nuclear pleomorphism
● Variable mitotic rate
● Often tumor necrosis
Positive stains
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● Epithelial markers - cytokeratin (CAM5.2 in 94%, AE1/AE3 in 75%, pan-keratin in 67%), EMA (66%)
● Smooth muscle markers - calponin (86%), S100 or GFAP in most cases
● Occasional alpha smooth muscle actin, p63
Molecular / cytogenetics
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● Different cytogenetics from salivary gland myoepithelial carcinoma and breast ductal carcinomas with myoepithelial differentiation, based on study in one case (Cancer Genet Cytogenet 2008;183:121)
Differential Diagnoses
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● Malignant mixed tumor - malignant cartilage or bone also present
End of Soft Tissue Tumors Part 3 - Muscle, Vascular, Nerve, Other > Myoepithelial carcinoma
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