12.6.2Location

•Extremities: 42%

•Retroperitoneal area: 25%

•Sacral area: 21%

•Other locations: rarely

12.6.3Pathology and Cytogenetics

•Originates from peripheral nerve (plexus, spinal nerve roots), histologically similar to spindle cells; difficult to differentiate from fibrosarcoma; rate of mitosis correlated with grade of malignancy

•Morphological differences between malignant nerve sheath tumor and schwannoma by electron microscopy

•Immunohistochemistry: S-100 antibody positive

•Genetic: high association between neurofibromatosis with 17q11.2 chromosomal alterations and chromosomal abnormities of chromosomes 1, 11, 12, 14, 17, 22, which may be associated with loss of tumor suppressor genes on 17p and 22q

•Other histological subtypes: epithelial, glandular, or cartilaginous forms

•Due to neuroectodermal origin, there are mesodermal and ectodermal variants:

–Melanoma-rhabdomyoblastoma variant

–Epithelial, mucin-producing variant

12.6.4Clinical Manifestations

•Swelling

•Rarely pain

12.6.5Therapy

•Approach similar to that used in grade III and IV fibrosarcoma and rhabdomyosarcoma (see above)

12.7Leiomyosarcoma

12.7.1Incidence

•Five percent of soft tissue sarcomas in childhood

•Fifty percent in children less than 5 years old

•Second peak during adolescence

•Ratio of males to females is 1:1

•Association with HIV infection and other immune deficiencies

152 P. Imbach

12.7.2 Location

• Visceral, mainly gastrointestinal (stomach), genitourinary, retroperitoneal, or rarely in peripheral soft tissue

12.7.3 Pathology

•Histologically spindle cells with cigar-shaped nuclei and prominent nucleoli; sometimes longitudinal myofibrils detectable in the cytoplasm

•Degree of malignancy depends on:

–Number of mitoses (more than ten mitoses per microscopic field is prognostically unfavorable)

–Degree of anaplasia appears important prognostically

12.7.4Clinical Manifestations

•Depends on the localization of the sarcoma

•Gastrointestinal: melena, hematemesis, anemia; rarely vomiting, abdominal pain, nausea, and weight loss

•Genitourinary:

–Location: uterus, bladder, prostate

–Symptoms: vaginal bleeding, dysuria, retention of urine; visible or palpable tumor

•Peripheral leiomyosarcoma: visible tumor

12.7.5Therapy

•Favorable histology: usually radical surgical resection is sufficient

•Unfavorable histology:

–Often metastatic spread to lung, liver, or regional lymph nodes; genitourinary sarcoma with intra-abdominal spread of lymph nodes

–Combined treatment as in rhabdomyosarcoma (see above), including surgical excision, which is critical, since the leiomyosarcomas are not very sensitive to radiotherapy

12.7.6Prognosis

•In general, 20–25% 5-year survival

•Unfavorable prognosis in tumor involving visceral areas (high rate of metastatic spread), favorable prognosis in other primary locations with total resection