Nonrhabdomyosarcoma Soft Tissue Sarcomas Workup

Updated: Mar 27, 2015
  • Author: Justine K Walker, MD; Chief Editor: Robert J Arceci, MD, PhD  more...
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Workup

Laboratory Studies

In patients with nonrhabdomyosarcoma soft tissue sarcoma (NRSTS), a baseline CBC count with differential provides parameters before therapy and is useful in evaluating for involvement of the bone marrow.

Chemical tests to assess renal function and creatinine clearance provide baseline parameters before chemotherapy is given and further testing is performed.

Liver function testing provides baseline parameters before chemotherapy and is helpful in evaluating for hepatic involvement.

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Imaging Studies

Chest radiography and chest CT are useful for evaluating for lung involvement. Perform these studies before the use of general anesthesia, which can cause pulmonary changes that might make the interpretation of images difficult.

CT and MRI are used to determine the size of the mass and the extent of local involvement and impingement on adjacent structures. CT and MRI also help in defining options for surgical resection. Contrast-enhanced studies are most helpful. Abdominal CT scanning is important for assessing abdominal primary lesions and to determine hepatic involvement.

Radionucleotide bone scanning is necessary to rule out bony involvement.

Plain radiography of the involved areas may be useful in the initial evaluation of a mass, depending on its location and suspected involvement of bony structures.

The roles of positive emission tomography (PET)-CT and of18 F-fluorodeoxyglucose (FDG) PET to image NRSTS in children have not been well established. However, PET-CT may prove beneficial in distinguishing normal from pathologic processes, in the initial staging of a sarcoma, in monitoring responses to therapy, and in detecting recurrences. [12, 13]

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Other Tests

A cardiologist may need to be consulted to perform cardiac ECG and echocardiography in patients who will receive anthracycline-based chemotherapy or radiation therapy to the chest.

Testing of renal glomerular filtration or creatinine clearance may be necessary before renal-toxic chemotherapy agents (eg, cisplatin, ifosfamide) are administered.

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Procedures

Carefully planned and executed biopsy of the mass lesion is required for diagnosis.

Whatever technique is used, adequate tissue must be obtained to allow for histology, immunostaining, and other studies including cytogenetics, fluorescent in situ hybridization (FISH), and molecular pathology. If possible, surgery should be accomplished in a manner that does not compromise the possibility for later local surgical control of the tumor.

A surgeon with expertise in oncologic surgery should perform this procedure. The surgeon's specific discipline depends on the location of the mass.

The best approach for small lesions in accessible areas may be excisional biopsy.

Large masses involving critical organs or structures may require incisional biopsy for diagnosis.

Delay the definitive surgical procedure until after adjuvant chemotherapy, radiation therapy, or both are given to shrink the tumor.

Fine-needle aspiration biopsy may be possible in certain cases. However, an open procedure is required if this technique yields nondiagnostic pathologic material.

Minimally invasive surgical techniques using fiberoptic surgical procedures may be appropriate in certain biopsy situations.

Consider long-term venous access. In most cases, placement of an implanted or externalized central venous catheter is useful for monitoring laboratory results and for delivering chemotherapy and supportive care.

Bilateral bone marrow aspirates and biopsy samples should be obtained in most cases to rule out tumoral involvement of the bone marrow. Strongly consider examining the bone marrow in all patients with NRSTS.

In children, these procedures are best performed in the posterior iliac crests.

These tests should be accomplished in conjunction with another procedure requiring sedation, if possible.

If patients have parameningeal tumors or tumors involving the CNS, lumbar puncture may be necessary to rule out contamination of the cerebrospinal fluid (CSF) with tumor cells.

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Histologic Findings

Diagnosis of an NRSTS can be confirmed only with biopsy of the mass. Diagnosis of a specific tumor depends on the mesenchymal and/or support tissue it most closely represents. Immunostaining, electron microscopy, cytogenetic analysis, and tests for molecular markers of genetic rearrangements may all be used for final diagnosis, depending on the differentiation of the specific tumor. Many of the NRSTSs are characterized by chromosomal translocations that lead to a fusion of two genes. The resultant fusion gene can be detected by polymerase chain reaction (PCR)-based techniques. NRSTSs possess a wide range of histologic features.

A tumor is classified as low-grade or high-grade on the basis of its potential to metastasize. Low-grade lesions are unlikely to metastasize. Certain types of tumors are arbitrarily considered high grade; examples are synovial cell sarcomas and malignant peripheral nerve sheath tumors. Malignant and metastatic potential are based on the degree of anaplasia and mitotic activity the tumor specimen exhibits.

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Staging

No staging system is validated for NRSTSs in children. Two systems are currently in use: the surgicopathologic grouping system used by the Intergroup Rhabdomyosarcoma Study (IRS), which is based on the amount of tumor remaining after initial surgery, and the American Joint Commission for Cancer (AJCC) staging system for Soft Tissue Sarcomas [14] . This is the staging system that is being used in the current COG trial for NRSTS.

Table. American Joint Commission for Cancer Staging (Tumor, Node, and Metastases [TNM] System) (Open Table in a new window)

  Primary Tumor Regional Lymph Nodes Distant Metastasis Histologic Grade
Stage I Any tumor size, superficial or deep N0 M0 G1 or G2
Stage II T1a (tumor < 5 cm, superficial) N0 M0 G3
T1b (tumor < 5 cm, deep) N0 M0 G3
T2a (tumor >5 cm, superficial) N0 M0 G3
Stage III T2b (tumor >5 cm, deep) N0 M0 G3
Stage IV Any tumor size, superficial or deep N1 M0 or M1 G1, G2, or G3
Any tumor size, superficial or deep N0 or N1 M1 G1, G2, or G3

G1 = well differentiated; G2 = moderately differentiated; G3 = poorly differentiated; M0 = no distant mets; M1 = distant mets; N0 = no regional LN mets; N1 = regional LN mets

Intergroup Rhabdomyosarcoma Study (IRS) groups staging is as follows:

  • Group I - Complete resection with negative margins
  • Group II - Microscopic residual disease after resection
  • Group III - Incomplete resection or biopsy with gross residual tumor
  • Group IV - Metastatic disease present at time of diagnosis
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