Soft tissue tumors are diverse in type and nomenclature, with particularly complex pathological morphology in malignant cases. As understanding continues to evolve, frequent revisions to pathological classifications create significant challenges for clinicians, making these tumors far more difficult to manage than other malignancies. Recent updates to soft tissue tumor classification have introduced new terminology changes, such as renaming "synovial sarcoma" to "malignant tenosynovial giant cell tumor"—a level of nomenclature instability rarely seen in other tumor types.

bubble_chart Epidemiology

Soft tissue malignant tumors, also known as sarcomas, account for only about 1% of all malignant tumors. In childhood, soft tissue sarcomas rank fourth in incidence after leukemia, brain tumors, and lymphoma. The most common types of soft tissue sarcomas include fibrosarcoma, synovial sarcoma, rhabdomyosarcoma, liposarcoma, leiomyosarcoma, and mesothelioma. During childhood, both domestic and international data indicate that rhabdomyosarcoma has the highest incidence, followed by fibrosarcoma.

bubble_chart Etiology

Based on the current understanding of soft tissue tumors, their occurrence is not attributed to a single factor. Numerous pieces of evidence indicate that ionizing radiation is a cause of fleshy tumors, such as fibrous fleshy tumors developing in the chest after irradiation following mastectomy. In addition, other factors are also associated, including congenital malformations, familial inheritance, foreign body stimulation, chemical substance stimulation, viral factors, and endocrine factors, among others.

bubble_chart Pathological Changes

bubble_chart Diagnosis

Based on medical history and clinical manifestations, soft tissue tumors are not difficult to differentiate from non-neoplastic masses. The key diagnostic points are as follows:

(1) Patients typically notice a painless, progressively enlarging mass over weeks or months, while systemic symptoms such as fever, weight loss, and general malaise are rare.

(2) Although clinically uncommon, an important tumor-related syndrome is hypoglycemia, often associated with fibrosarcoma.

(3) **X-ray examination**: X-rays help further assess the extent, radiolucency, and relationship of soft tissue tumors to adjacent bone. A well-defined border often suggests a benign tumor, whereas a clear border with calcification may indicate a highly malignant sarcoma, commonly seen in synovial sarcoma and rhabdomyosarcoma.

(4) **Ultrasonography**: This method evaluates tumor size, capsule boundaries, and internal echogenicity, distinguishing benign from malignant tumors. Malignant tumors are typically large with indistinct borders and blurred echoes, such as rhabdomyosarcoma, synovial sarcoma, and malignant fibrous histiocytoma. Ultrasound can also guide needle aspiration cytology for deep-seated tumors, making it an economical, convenient, and non-invasive diagnostic tool.

(6) **MRI examination**: MRI compensates for the limitations of X-ray and CT by displaying tissue layers and the full extent of tumors in longitudinal sections. It provides clearer images for retroperitoneal soft tissue tumors, pelvic tumors extending to the buttocks or thigh roots, popliteal fossa tumors, and the degree of bone or marrow invasion, serving as an excellent basis for treatment planning.

(7) **Pathological examination**:

**1. Cytological examination**: A simple, rapid, and accurate pathological method, most suitable for: ① Ulcerated soft tissue tumors, where smears or scrapings are collected for microscopic confirmation; ② Pleural or peritoneal effusions caused by sarcoma, requiring immediate centrifugation and concentration of fresh specimens before smearing; ③ Needle aspiration smears for large, deep tumors planned for radiotherapy or chemotherapy, as well as metastatic or recurrent lesions.

**2. Incisional biopsy**: Performed when a soft tissue tumor is ulcerated and cytological smears are inconclusive.

**3. Excisional biopsy**: Often performed during surgery. For large limb tumors requiring amputation, a biopsy is taken beforehand for definitive pathological diagnosis. If the tumor is located in the chest, abdomen, or retroperitoneum and cannot be completely resected, a biopsy is taken to confirm the diagnosis before radiotherapy or chemotherapy.

**4. Excisional biopsy**: Suitable for small soft tissue tumors, where the tumor and surrounding normal tissue are completely removed for pathological examination.

(1) Surgical Treatment

1. Radical surgery: Tumors in all locations must be excised along with the surrounding normal tissue. To ensure complete removal, it is often necessary to sacrifice some normal structures. The surgical resection should also include the biopsy site, skin, and adjacent muscle tissue. For muscle tumors, the affected muscle should be completely excised from end to end. Lymph node dissection is performed only when clinical evidence shows lymph node involvement.

2. Debulking surgery: This method is used for some soft tissue tumors that cannot be completely removed, followed by other non-surgical treatments to improve the patient's quality of life and prolong survival. For example, large malignant retroperitoneal liposarcomas may first undergo debulking surgery, followed by radiotherapy, which can yield good results.

3. Amputation: This is suitable for advanced-stage large tumors with ulceration and massive bleeding that cannot be controlled; or when accompanied by severe infections such as sepsis or tetanus, posing a threat to the patient's life; or when the tumor grows rapidly and causes severe pain that is difficult to manage with medication; or when the limb has already suffered a pathological fracture and lost mobility. Amputation should only be considered when no other methods can save the limb.

(2) Radiotherapy Radical surgery may result in functional injury, amputation, or joint disarticulation. An alternative treatment is the combined use of surgery and radiotherapy. Postoperative adjuvant radiotherapy mainly suppresses microscopic subclinical lesions remaining in the surgical field but is often ineffective against bulky or nodular masses. Therefore, scholars believe that even local tumor excision followed by radiotherapy can achieve results comparable to radical surgery, including amputation, while preserving the limb. Radiotherapy alone is palliative and cannot achieve a cure. In recent years, many scholars have proposed preoperative radiotherapy, noting that it may sometimes be superior to postoperative radiotherapy. Preoperative radiotherapy can shrink large tumors and often creates a tissue reaction zone between the tumor and normal tissue, with grade I edema, making surgical separation easier and enabling the resection of tumors previously deemed inoperable. Additionally, most tumor cells lose viability after radiotherapy, reducing the risk of recurrence even if residual tumor cells remain in the surgical field. Another advantage is that the vessels surrounding soft tissue sarcomas often atrophy, narrow, or even fibrose and occlude after radiotherapy, losing circulatory capacity, which reduces the chance of tumor spread during surgery. The main drawback of preoperative radiotherapy is the difficulty in postoperative wound healing, requiring special attention.

(3) Chemotherapy Many drugs are effective against soft tissue sarcomas, primarily ADM, DTIC, CTX, IFO, and KSM. The CYV ADIC combination regimen is generally considered the most effective. The specific protocol is: CTX 600mg on day 1, VCR 2mg on day 1, KSM 400μg on day 1, and DTIC 250mg on days 1–5, with a cycle lasting 3–4 weeks. Chemotherapy is divided into postoperative adjuvant chemotherapy and neoadjuvant chemotherapy, i.e., preoperative chemotherapy.

1. Preoperative chemotherapy: Large, highly malignant soft tissue sarcomas are suitable for preoperative chemotherapy, which can shrink the tumor, improve resection rates, and avoid the need for amputation.

2. Postoperative chemotherapy: The combination of surgery and chemotherapy has been widely applied in the clinical treatment of various malignant tumors. For highly malignant soft tissue fleshy tumors, it should be initiated shortly after surgery to potentially reduce distant metastasis and improve survival rates. If the interval is too long, the treatment may prove ineffective. The authors believe that using chemotherapy is better than not using it, early application is better than late application, and preventive use is better than therapeutic use. Generally, the duration of medication is 1 year for stage I and IIa, and 2 years for stage IIb to III.