What Is Alveolar Rhabdomyosarcoma?

Rhabdomyosarcoma is a malignant tumor that originates in striated muscle cells or mesenchymal cells that differentiate into striated muscle cells. It is the most common type of soft tissue sarcoma in children. The incidence of rhabdomyosarcoma is second to malignant fibrous histiocytoma and liposarcoma and ranks third in soft tissue sarcoma. Adults have less hair and more men than women. Embryonic rhabdomyosarcoma is more common in children before the age of 8 (mean age 6 years); acinar rhabdomyosarcoma is found in adolescent men (mean age 12 years); polytype rhabdomyosarcoma is common in adults and can be seen in children.

Basic Information

English name

rhabdomyosarcoma

Visiting department

Oncology; Orthopedics

Multiple groups

Embryo type: children and adolescents; acinar type: male adolescents; polymorphism: adult

Common locations

Embryo type: head, neck, urogenital tract and retroperitoneum; acinar type: limbs, head and neck, trunk, perineum, etc.

Common symptoms

Embryo type: painful or painless mass, redness and swelling on the surface of the skin, high skin temperature; acinar type: painful or painless mass, pain, compression symptoms, and sensory disorders, etc.

Causes of rhabdomyosarcoma

The cause of rhabdomyosarcoma is not clear. It is a soft tissue malignant tumor composed of rhabdomyoblasts of various degrees of differentiation. The disease may be related to genetic factors, chromosomal abnormalities, gene fusion and other factors.

Clinical manifestations of rhabdomyosarcoma

Embryonic rhabdomyosarcoma accounts for about two-thirds of rhabdomyosarcoma. It occurs in children and adolescents, and the age distribution shows two peaks, namely after birth and late adolescence, with an average age of 5 years. Occurs on the head, neck, genitourinary tract, and retroperitoneum. The course is short, the main symptoms are painful or painless mass, redness and swelling on the skin surface, and high skin temperature. Tumors vary in size and stiffness, and most tumors are fixed at the time of consultation. The tumor grows fast, and there may be skin ulceration and bleeding. Pain can occur when a tumor compresses a nerve. Head and neck masses may have prominent eyeballs, bloody secretions, nosebleeds, swallowing and breathing problems. Tumors of the genitourinary system are manifested as vaginal bloody secretions, hematuria, and urinary retention, with anal fingers touching the pelvic mass. This type usually metastasizes to the retroperitoneal lymph nodes and the lymph nodes in the region.

Acinar rhabdomyosarcoma is more common in adolescents than males. Frequent limbs, head and neck, trunk, perineum, etc. can also occur in the eye sockets. The main symptoms are painful or painless masses. Tumors can cause pain, compression symptoms and sensory disturbances when they compress the surrounding nerves and invade surrounding tissues and organs. Lymph node metastasis and hematogenous dissemination can occur at an early stage, and hematogenous dissemination to the lungs.

Polymorphic rhabdomyosarcoma mainly occurs in adults, and is more common in 40 to 70 years old. Frequent limbs and torso, located in muscle hypertrophy, such as quadriceps, adductors of thighs and biceps. Tumors often infiltrate beyond the capsule, forming multiple nodules at sites that are far apart from the muscle. The duration of the disease varies, with people over 20 years. The main symptom is a painful or painless mass. The mass is located in the muscle and the boundaries are unclear. When the tumor invades the skin surface, there may be high skin temperature, ulceration and bleeding. This type is characterized by large tumors, mostly in the 5 to 10 cm, but also up to 40 cm. The mass is hard and cystic. Polymorphic rhabdomyosarcoma can cause lymph node metastasis.

Rhabdomyosarcoma examination

HE staining is used to observe rhabdomyosarcoma cells under an optical microscope. Sometimes, it can be difficult to confirm the diagnosis due to low cell differentiation and rhabdomyostasis. Immunohistochemical staining is a reliable method for the diagnosis of rhabdomyosarcoma. In this case, the tumor cells were observed in a bundle-like arrangement under a light microscope. They are spindle-shaped and similar to fibrosarcoma. A few tumor cells have obvious eosinophils in the cytoplasm, that is, rhabdomyoblasts. Myoglobin was positive in immunohistochemical examination.

Generally there are no typical radiological features and no calcification. Tumors can invade and destroy adjacent bones, especially the skull, forearms, hands, and feet. CT and MRI examinations with contrast agents can better show the location, volume, edge of the tumor and its relationship with surrounding tissues. Intravenous pyelography can find irregular filling defects in the bladder and hydronephrosis. Other tests include bone scans (suspected bone metastases) and lymphangiography (suspected lymph node metastases).

Rhabdomyosarcoma diagnosis

Head

Rhabdomyosarcoma of the head and neck is mostly embryonic in children, and grape-like sarcoma in the ears, nose, and sinuses. All patients were treated with a lump, and their symptoms included exophthalmos, sound changes, difficulty swallowing, respiratory obstruction, cough, and secretions from the external auditory canal. If it invades the nerves, regurgitation pain occurs; tumor swelling and invasive growth can aggravate symptoms and brain symptoms. If metastases occur, corresponding symptoms occur.

Eye socket

Rhabdomyosarcoma can come from the eye muscles or lacrimal glands, and is more common in 7 to 8-year-old boys, causing unilateral exophthalmos. The disease progressed rapidly, ptosis occurred in 1/3 of the children, headache in 10% of the children, and bone destruction was seen on X-rays. In children with unilateral exophthalmos, a neurological examination is required, including carotid X-rays and brain scans. The differential diagnosis should include leukemia and neuroblastoma. Leukemia peripheral blood and bone marrow smears are easy to distinguish. When neuroblastoma invades the orbit, the lesions in other parts of the body are more obvious and can be identified.

3. ear

Tumors can occur in the external auditory canal, middle ear, mastoid process, or paranasal sinuses, often invading only one ear, the contralateral side is normal, and there is often unilateral hearing loss, which often goes unnoticed. Often there is a polyp-like mass in the outer ear canal and bloody secretions in the ear. It is easy to be mistaken for inflammatory polyps. Therefore, this disease should be considered especially when children with intra-ear inflammation are not effective for antibiotic treatment. Rarely, there is a mass behind the ear, which grows rapidly. It may be an insignificant bulge reported at the first diagnosis, which is soft and can increase to an astonishing degree at the follow-up. Due to painlessness, the diagnosis is often late. Occasionally, facial paralysis is the main complaint. Dizziness is a rather advanced symptom. The tumor spreads from the middle ear to the mastoid and invades the posterior cranial fossa through the inner plate.

4, mouth, neck

Rhabdomyosarcoma is a common malignant tumor in childhood, accounting for 50% of all children's soft tissue sarcomas, 45% of which occur in the head and neck. Among head and neck rhabdomyosarcoma, 25% to 35% are primary in the orbit. Rhabdomyosarcoma is divided into embryonic, acinar, and pleomorphic. 80% of rhabdomyosarcoma occurring in the orbit are embryonic. Embryonic rhabdomyosarcoma includes spindle cells, grape-like and anaplastic rhabdomyosarcoma, and is easily confused with tumors such as non-Hodgkin's lymphoma and fibrosarcoma. Embryonic rhabdomyosarcoma originates from the floor of mouth, tongue, uvula, soft palate, nasopharynx, larynx, lip, nose, gingival, temporal, cheek, mandibular muscle, parotid gland and neck muscle. Superficial patients present as simple painless masses, which can be misdiagnosed as benign tumors at an early stage. Laryngeal tumors in young children can cause hoarseness and acute respiratory obstruction.

Rhabdomyosarcoma treatment

Surgical treatment

Rhabdomyosarcoma is mainly surgically removed, and the scope of the resection includes all muscles where the tumor is located. For embryonic rhabdomyosarcoma, in addition to resection, chemotherapy and radiotherapy should be combined to relieve symptoms; pleomorphic rhabdomyosarcoma is not effective for chemotherapy and radiotherapy.

Biopsy of the tumor showed that the effect of complete surgical removal of rhabdomyosarcoma is better. Rhabdomyosarcoma can be completely removed in only 10% of patients. Even in patients with complete resection, chemotherapy and radiation therapy are necessary because rhabdomyosarcoma is extremely metastatic.

During surgery, a biopsy of the lymph nodes in the tumor area is required. A complete surgical resection of rhabdomyosarcoma in the head and neck must be performed by an otolaryngologist, orthopedic surgeon, maxillofacial surgeon, and neurosurgeon. If a complete resection affects the appearance and function of the face, surgery will be postponed until the end of the chemotherapy and radiotherapy sessions. Whether to perform a second facial surgery depends on the surgical site and the effects of chemotherapy and radiotherapy.

The basic requirement for surgical resection of rhabdomyosarcoma is a biopsy. The format of the biopsy is based on medical imaging results, tumor location and size, patient age and health, and doctor's experience. The purpose of complete tumor removal during surgery is to avoid secondary surgery.

2. Chemotherapy

When rhabdomyosarcoma cannot be completely removed, the patient must undergo chemotherapy. Chemotherapy can completely eliminate residual tumors. Even if the tumor appears to be completely removed, chemotherapy is still necessary.

There are many cytotoxic chemotherapy drugs, and most of them are administered intravenously. The main drugs used for completely resected embryonic rhabdomyosarcoma are vincristine and dactinomycin. Cyclophosphamide is also commonly used for class II and III tumors.

Ifosfamide can kill rhabdomyosarcoma cells, which is expected to improve the survival rate of patients with type . Chemotherapy drugs can also kill some normal cells and cause side effects. Side effects include hair loss, nausea, vomiting, loss of appetite, fatigue, anemia, and vulnerability to infection. Most of the side effects disappear after stopping the medication, and some drugs can permanently damage the cells in the ovaries and testes, making it difficult or even infertile. Damage to the kidneys and bladder by cyclophosphamide or ifosfamide is also permanent.

3. Radiotherapy

For rhabdomyosarcoma, radiotherapy is a very effective method. It can be used as an adjuvant treatment for surgery. The radiation dose should be selected according to age and location. The radiation field should include the tumor bed and normal tissues around 2 to 5 cm. The effective radiation dose is not Less than 40Gy.

4. Magnetic induction therapy

Magnetic induction therapy is based on the principle that ferromagnetic materials generate heat under an alternating magnetic field, so that the tumor tissue is heated to an effective temperature, thereby achieving the purpose of treatment. Magnetic induction therapy has the characteristics of targeting, conformability, self-controlling temperature, internal heating, repeatability, large temperature difference between normal tissue and tumor, etc. It is expected to overcome the shortcomings of previous local tumor thermal treatment methods and become a new treatment for tumors. Effective means.

Prognosis of rhabdomyosarcoma

The incidence of rhabdomyosarcoma will affect the prognosis. The prognosis of head and neck and genitourinary region is better than that of extremity and trunk. At present, the combined treatment of combined radiotherapy and chemotherapy, such as those without metastasis before starting treatment, the 5-year survival rate is close to 80%. Two-thirds of children with rhabdomyosarcoma survive, the most important of which is the resection of the tumor: children with class rhabdomyosarcoma have a good treatment effect, and more than 90% will not relapse; 80% of class and class III 70% of them will survive for a long time; the prospects for category IV children are not good, and the 5-year survival rate is less than 30%. The prognosis of children with acinar rhabdomyosarcoma is not as good as that of children with embryonal rhabdomyosarcoma, and they need to receive more intense chemotherapy.