Pleomorphic Rhabdomyosarcoma
Khin Thway, BSc, MBBS, FRCPath
Key Facts
Terminology
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High-grade sarcoma occurring almost exclusively in adults and displaying evidence of skeletal muscle differentiation
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Diagnosis requires identification of pleomorphic rhabdomyoblasts and expression of skeletal muscle specific immunohistochemical markers
Clinical Issues
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Older adults
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Deep soft tissues of lower extremity
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Multiple other sites
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Microscopic Pathology
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Morphology of pleomorphic sarcoma
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Markedly atypical spindle to polygonal cells
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Pleomorphic polygonal rhabdomyoblasts may be present
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Expression of desmin and myogenic markers
Pleomorphic rhabdomyosarcoma is shown with sheets of markedly anaplastic, frequently bizarre  or multinucleate  polygonal cells. The morphology is indistinguishable from other pleomorphic tumors. |
In this specimen, the tumor shows a fascicular architecture with bundles of atypical spindle cells with vesicular or hyperchromatic nuclei. |
TERMINOLOGY
Definitions
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High-grade sarcoma occurring almost exclusively in adults and displaying evidence of skeletal muscle differentiation
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Diagnosis requires identification of pleomorphic rhabdomyoblasts and expression of skeletal muscle specific immunohistochemical markers
CLINICAL ISSUES
Epidemiology
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Age
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Older adults
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Median: 6th decade
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Very rare cases reported in children and adolescents
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Gender
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M>F
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Site
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Deep soft tissues of lower extremity, particularly thigh
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Abdomen/retroperitoneum
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Spermatic cord and testes
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