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- Discussion:
    - describes sarcomas of smooth muscle (leiomyosarcoma) & sarcomas of skeletal muscle (rhabdomyosarcoma);
    - rhabdomyosarcomas make up 2/3 of pediatric soft-tissue sarcomas;
    - rhabdomyosarcoma has two forms:
         - embryonal rhabdomyosarcoma:
               - is the most common form of this tumor in children and young adolescents;
               - occurs in head, neck, retroperitoneum and genitourinary system, and occurs rarely in the extremities;
               - metastasis is frequent and prognosis is grave;
         - alveolar rhabdomyosarcoma:
               - tends to occur in older children and adolescents;
               - metastasis is common;
               - w/o recurrent metastatic lesions, survival may be 80% or higher;
         - adult rhabdomyosarcoma;
               - develops in the limbs;
    - angiography: 
              - shows the marked vascularity of leiomyosarcomas;

- Histology:
    - reveals smooth muscle spindle cells w/ blunt ended nuclei;
     - presence of cross-striations in malignant cells needs to be established by electron microscopy to validate the diagnosis;
            - this helps r/o malignant fibrous histiocytoma,
    - adult form:
          - high grade lesion;
          - background of undifferentiated malignant cells admixed w/ malignant myoblasts that appear as large, racquet shaped cells;
     - embryonal form:
          - glandular pattern;
          - lacks the large, racquet shaped myoblasts;

- Diff Dx:
    - proliferative myositis

- Treatment:
    - note that rhabdomyosarcoma can spread via lymph nodes, which impacts on prognosis;
              - other sarcomas which spread via lymph nodes include: clear cell sarcoma, epithelioid sarcoma, synovial sarcoma 
    - some authors recommend bone marrow aspiration and biopsy at two or more sites for staging purposes;
    - because metatasis to lymph notes affects treatment, surgical sampling of ipsilateral inguinal or axillary lymph nodes is recommended;
    - treatment involves combination of surgery, chemotherapy, and irradiation;
    - obviously XRT is not desirable in children because of its effect on the growing limb and because of possibility for causing secondary tumors (can be up to 20%);
    - chemotherapy often invovles: cyclophosphamide
    - patients w/ stage IIb leiomyosarcoma who have major neurovascular involvement often require ammputation

Primary myectomy for sarcoma


Prognosis in childhood rhabdomyosarcoma of the extremity.

Factors predictive of mortality in pediatric extremity rhabdomyosarcoma.

Childhood Rhabdomyosarcoma of the trunk and extremities