146	P. Imbach

–Blockade of tumor growth by tyrosine kinase-receptor antagonists and endothelial cell growth antagonists (e.g., endostatin and angiostatin)

–Other immunotherapies include monoclonal antibodies or cytotoxic T-cells targeting specific proteins of RMS, that is PAX

•Palliative therapy: irradiation, surgery, chemotherapy

12.2.14 Secondary Tumors

Of 1,770 children in the IRS I and II, 22 had secondary cancers, mainly osteosarcoma and leukemia (acute myelogenous leukemia, AML, or myelodysplastic syndrome, MDS).

12.3Fibrosarcoma

12.3.1 Incidence

• Eleven percent of all soft tissue sarcomas in childhood

• Seventy-five percent in children less than 10 years old, including 36% in newborns (congenital or infantile fibrosarcoma)

• Ratio of males to females is 1.2:1

12.3.2 Location

Ranked by frequency:

•Lower extremities

•Upper extremities

•Head and neck

•Trunk

•Pelvic area

•Rarely, retroperitoneal and visceral area, chest

12.3.3Pathology and Cytogenetics

•Fibrosarcoma, mainly in muscles of the extremities

•Tumor infiltration into normal tissue

•Histology:

–Congenital form: uniform fibroblasts or myofibroblasts; low rate of mitosis; cytogenetics: translocation t(12;15)

–Fibrosarcoma: anaplastic spindle cells in herringbone pattern with parallel arrangements of tumor cells, collagen detectable; cytogenetics: translocation t(x;18), t(2;5), t(7;22); mutation of tumor suppressor gene TP53 associated with poor prognosis