Pretibial skin also common
Uncommon on face
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Benign but up to 50% recur
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Rare intraoral, orbital, intradural, and paraspinal cases
Microscopic
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Multiple lobules with abundant myxoid matrix
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Well-defined lobular architecture and dense fibrous septa
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Usually limited to dermis and subcutis
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Spindle-shaped and epithelioid cells
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Interconnecting cords, networks, syncytial nests, ring-like structures
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Stellate and vacuolated cells common
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No atypia, very low mitotic rate
Ancillary Tests
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SMA, desmin, CD68, HMB-45, synaptophysin, chromogranin-A, CD31 (-)
Top Differential Diagnoses
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Superficial angiomyxoma
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Superficial acral fibromyxoma
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Myxoid dermatofibrosarcoma protuberans
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Myxofibrosarcoma (low grade)
TERMINOLOGY
Synonyms
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Cutaneous lobular neuromyxoma, perineurial myxoma, pacinian neurofibroma, myxoid tumor of nerve sheath
Definitions
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Benign cutaneous nerve sheath tumor with Schwann cell differentiation, abundant myxoid matrix, and well-defined lobular architecture
CLINICAL ISSUES
Epidemiology
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Incidence
Rare; fewer than 100 reports
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Age
Mostly adults; median age: 34 years
Site
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Extremities
Fingers and hand most common
Pretibial skin common
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Rare intraoral, orbital, intradural, and paraspinal cases
Presentation
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Slowly growing, painless mass
Treatment
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Surgical approaches
Simple excision
Prognosis
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Benign and nonaggressive but often excised with positive margins
Up to 50% recur
MICROSCOPIC
Histologic Features
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Multiple myxoid lobules
Well-defined borders separated by dense fibrous septa
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Usually limited to dermis and subcutis