Table 1. Age Distribution of Soft Tissue Sarcomas (STSs) in Children Aged 0 to 19 Years (SEER 1975–2008) continued...
When a suspicious lesion is identified, it is crucial that a complete workup, followed by adequate biopsy be performed. Generally, it is better to image the lesion prior to any interventions. Plain films can be used to rule out bone involvement and detect calcifications that may be seen in soft tissue tumors such as extraskeletal osteosarcoma or synovial sarcoma. Chest radiography and computed tomography (CT) of chest are essential to assess the presence of metastases. CT can be used to image intra-abdominal tumors, such as liposarcoma, and magnetic resonance imaging (MRI) can be used for extremity lesions.
Nonrhabdomyosarcomatous soft tissue tumors are fairly readily distinguished pathologically from rhabdomyosarcoma and Ewing sarcoma; however, classification of childhood nonrhabdomyosarcomatous STS type is often difficult. A core-needle biopsy or small incisional biopsy that obtains adequate tumor tissue is crucial to allow for conventional histology, immunocytochemical analysis, and other studies such as light and electron microscopy, cytogenetics, fluorescence in situ hybridization, and molecular pathology,[21,22] given the diagnostic importance of translocations. Needle biopsy techniques must obtain an adequate tissue sample and usually require obtaining multiple cores of tissue. Image guidance using ultrasound, CT scan, or MRI may be necessary to ensure a representative biopsy. Incisional biopsies are acceptable but should not compromise subsequent wide local excision, and excisional biopsy of the lesion must be avoided. Transverse extremity incisions should be avoided to reduce skin loss, as should extensive surgical procedures prior to definitive diagnosis. For these reasons, open biopsy or multiple core-needle biopsies are strongly encouraged so that adequate tumor tissue can be obtained to allow for crucial studies to be performed and to avoid limiting future treatment options.
A single-institution analysis of adolescents and adults compared patients with unplanned excision of STS to stage-matched controls. In this retrospective analysis, unplanned initial excision of STS resulted in increased risk for local recurrence, metastasis, and death, and this increase was greatest for high-grade tumors.[Level of evidence: 3iiA]
Many nonrhabdomyosarcomatous STSs are characterized by chromosomal abnormalities. Some of these chromosomal translocations lead to a fusion of two disparate genes. The resulting fusion transcript can be readily detected by using polymerase chain reaction-based techniques, thus facilitating the diagnosis of those neoplasms that have translocations. Some of the most frequent aberrations seen in nonrhabdomyosarcomatous soft tissue tumors are listed in Table 2.