12.3.4Differential Diagnosis

•Nodular fascitis

•Myositis ossificans

•Inflammatory pseudotumor

•Neurofibrosarcoma

•Malignant peripheral nerve sheath tumor/schwannoma

•Poorly differentiated embryonal rhabdomyosarcoma

•Monophasic (spindle cell) synovial sarcoma

12.3.5Clinical Manifestations

• Painless swelling of soft tissue and muscle

12.3.6Therapy

12.3.6.1 Surgical Procedures

• Primary total resection; amputation rarely necessary

• Regional lymph node biopsy indicated (involvement about 4–10%)

12.3.6.2 Radiotherapy

• Residual tumor after surgery or relapsing fibrosarcoma: 60–65 Gy necessary

12.3.6.3 Chemotherapy

•In metastatic fibrosarcoma: management as in rhabdomyosarcoma (see above)

•In patients with grade 3–4 fibrosarcoma: following resection, procedure as in rhabdomyosarcoma (see above)

12.3.7 Follow-Up

•Thirty to seventy-five percent of patients show relapse within 18–20 months after first diagnosis; late relapse within the first 20 years after initial disease is possible

•More than 50% of patients with grade 3–4 staging develop metastatic disease after localized tumor treatment (without systemic chemotherapy)

•Metastatic spread: mainly lung, CNS, and bladder