• Rare tumor with myoepithelial elements but no ductal differentiation
• May be related to parachordoma or mixed tumor

• Equal gender frequency, occurs in all ages, but mean age 38 years
• 20% occur in children, has an aggressive clinical course

• Extremities, limb girdles, viscera, head & neck

• 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)

• 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)

• Mean 5 cm, often well circumscribed

• 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 (median 8/10 HPF)
• Often tumor necrosis

Various images

p63

• 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

• EWSR1 rearrangements are common (Hum Pathol 2012;43:764)
• 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)

FISH

• Cellular extraskeletal myxoid chondrosarcoma: has NR4A3 rearrangement
• Malignant mixed tumor: malignant cartilage or bone also present

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