bubble_chart Overview

Rhabdomyosarcoma has an incidence rate second only to malignant fibrous histiocytoma and liposarcoma, ranking third among soft tissue sarcomas. The embryonal and alveolar types are more common in children and young adults, while the pleomorphic type is more prevalent in middle-aged and older individuals. It occurs more frequently in males than in females and is commonly found in the head, neck, and extremities, as well as in the genitourinary system.

bubble_chart Pathological Changes

1. Gross findings: Tumors in the head and neck region often measure 2–3 cm in diameter, while those in the limbs tend to be deeper, infiltrating muscles with indistinct boundaries. The cut surface appears fish-flesh-like, and larger tumors may exhibit areas of hemorrhage, necrosis, and mucoid degeneration.

2. Microscopic findings: Histological classification:

(1) Embryonal type: The tumor is predominantly composed of undifferentiated spindle and small round cells, resembling rhabdomyoblasts at the early embryonic stage (7–10 weeks). It is characterized by diffuse distribution of tumor cells within a myxoid stroma.

(2) Alveolar type: Mainly consists of undifferentiated round tumor cells with a tendency to form alveolar-like structures, resembling skeletal muscle at the embryonic stage (10–20 weeks). The tumor cells are round or oval with scant cytoplasm, though a few larger cells may resemble epithelial cells, showing more abundant eosinophilic cytoplasm, eccentric nuclei, and inconspicuous nucleoli. Rhabdomyoblastic fleshy tumor.

(3) Pleomorphic type: Displays a typical fleshy tumor pattern with highly cellular proliferation, primarily composed of rhabdomyoblasts corresponding to the late developmental stage (third stage), showing marked atypia. Large, atypical spindle cells are arranged haphazardly, with striking cellular pleomorphism. Common features include strap cells, eosinophilic giant cells, multinucleated tumor giant cells, and mitotic figures.

bubble_chart Clinical Manifestations

Embryonal rhabdomyosarcoma {|###|} mostly occurs in children under 10 years old, with a predilection for the head and neck, orbits, and genitourinary system.

Alveolar rhabdomyosarcoma {|###|} is most commonly seen in adolescents, frequently occurring in the lower limbs, followed by the head, neck, and trunk. The tumor has a rubbery consistency, often involves lymph node metastasis in addition to hematogenous spread, and has indistinct margins. Most cases result in death within one year.

Pleomorphic rhabdomyosarcoma {|###|} primarily affects adults over middle age. It predominantly arises in the extremities, especially the lower limbs, with deep thigh muscles being a common site. Tumor sizes vary, with some exceeding 20 cm in diameter. Pleomorphic rhabdomyosarcoma {|###|} frequently metastasizes hematogenously and involves lymph nodes more often than the other two types. Some cases progress slowly, with about one-third of patients surviving for approximately five years.

bubble_chart Treatment Measures

The principle of surgical treatment is to perform a wide resection and strive to preserve the limb. Since the recurrence rate after marginal resection can be as high as 80% or more, amputation remains necessary for patients in whom wide resection cannot be achieved in the limbs.

For tumors located in areas where wide resection is not feasible and amputation is not an option (e.g., non-limb sites), postoperative radiotherapy can help reduce recurrence. Chemotherapeutic agents such as ADM, CTX, VCR, and cisplatin are available, but their efficacy remains uncertain.

Rhabdomyosarcoma can metastasize early to regional lymph nodes, making it necessary to perform lymph node dissection in the drainage area during tumor resection.

Literature reports indicate that patients with N0.M0 have a five-year survival rate of approximately 45%, while those with M0 have a rate of around 30%. Due to the early occurrence of metastasis in patients, the overall five-year survival rate is approximately 25%.

bubble_chart Differentiation

Embryonal rhabdomyosarcoma should be differentiated from lymphoma and Ewing's sarcoma. Pleomorphic rhabdomyosarcoma should be differentiated from malignant fibrous histiocytoma and pleomorphic liposarcoma.