Pediatric Rhabdomyosarcoma

Introduction to pediatric rhabdomyosarcoma Rhabdomyosarcoma (rhabdomyosarcoma) is a malignant tumor that occurs from embryonic mesenchymal tissue. Rhabdomyosarcoma accounts for 15% of children's solid tumors and 50% of soft tissue sarcomas. basic knowledge Sickness ratio: 0.00015% Susceptible people: children Mode of infection: non-infectious Complications: cerebral palsy, nosebleed, urinary tract obstruction, hematuria, intestinal obstruction

Causes of rhabdomyosarcoma in children

(1) Causes of the disease

This disease is a soft tissue malignant tumor composed of various levels of different levels of rhabdomyoblasts. The cause of the tumor is unknown, but genetic factors are not excluded.

(two) pathogenesis

Staging

The classification of rhabdomyosarcoma of IRS is mainly based on clinical, especially preoperative and intraoperative conditions, and the biological characteristics of the tumor have not been reflected. Therefore, it is not excessive for surgical pathological stage, but the clinical classification of IRS is still widely accepted.

In the IRS, 20% of patients belong to grade I, 21% belong to grade II, 45% belong to grade III, and 14% belong to grade IV. Compared with IRSII, grade III patients have an increase in the number of patients, mainly because the rate of complete surgical resection is decreased. As a result, some tumors, such as those located in the pelvic area, are not completely resected for surgical purposes.

42% of grade I children occurred in the genitourinary system except the bladder-prostate, 31% occurred in the limbs, 39% of the grade II children were head and neck tumors except the meninges, and 46% of the grade III were heads. In cervical tumors, 31% of grade IV were limb tumors, 14% were meningeal tumors, and 41% were other types.

Lawrence and Gehan et al. analyzed the data of IRSII and determined that the location, size, extent of invasion and local lymph node metastasis have important significance for the survival of children without distant metastasis. They improved the clinical classification and Divided into 4 phases (Table 2), it has now been adopted by IRS IV. This staging is based on the biological characteristics of the tumor rather than the degree of surgical resection, which can better predict the prognosis (Table 3). In general, the tumor is Hair loss and distant metastasis are the most valuable indicators for determining prognosis.

2. Pathological changes

(1) The naked eye: except for the embryonic rhabdomyosarcoma, which is mucoid-like, and the growth in the cavity is polypoid-like. Other types are sputum-like, lobulated or nodular, with clear boundaries, no true envelope, and a softer cut surface. Gray or gray-red fish can be associated with bleeding and necrosis.

(2) Under the microscope:

1 Embryonic type: also known as children's type, consisting of early immature rhabdomyoblasts and primitive mesenchymal cells. The cells are fusiform, star-shaped, oval or elliptical, sparsely arranged, rich in mucous matrix, and more nuclear division. Longitudinal myofibrils or transverse stripes can be seen, which account for about 2/3 of rhabdomyosarcoma.

2 acinar type: more common in young people, mainly composed of undifferentiated small round, oval-shaped myoblasts, tumor cells arranged in acinar, tubular or fissure-like, shaped like embryonic myotubes.

(3) Polymorphic type: also known as adult type, mainly composed of large band-shaped, tennis-like polymorphic cells, megakaryocytes and multi-nuclear giant cells, with irregular nuclei, deep staining and more nuclear division.

In patients with difficult diagnosis, the positive rates of viable immunohistochemistry, myoglobin, desmin and vimentin were 72.2%, 55.5% and 88%, respectively, and myosin was 100%.

Pediatric rhabdomyosarcoma prevention

Refer to the general tumor prevention methods, understand the risk factors of tumors, and formulate corresponding prevention and treatment strategies to reduce the risk of tumors. There are two basic clues to prevent tumors. Even if tumors have begun to form in the body, they can help the body to improve resistance. These strategies are as follows:

1. Avoid harmful substances (promoting factors) that can help us avoid or minimize exposure to harmful substances.

Some related factors of tumorigenesis are prevented before the onset, and many cancers can be prevented before they are formed. A report in the United States in 1988 compared the international malignant tumors in detail and proposed many external factors of known malignant tumors. In principle, it can be prevented, that is, about 80% of malignant tumors can be prevented by simple lifestyle changes, and traced back. In 1969, Dr. Higginson's research concluded that 90% of malignant tumors are caused by environmental factors," "Environmental factors", "lifestyle" refers to the air we breathe, the water we drink, the food we choose to make, the habits of activities, and social relationships.

2. Improve the body's immunity against tumors can help improve and strengthen the body's immune system and cancer.

The focus of our current cancer prevention efforts should first focus on and improve those factors that are closely related to our lives, such as quitting smoking, eating properly, exercising regularly, and losing weight. Anyone who follows these simple and reasonable lifestyles can Reduce the chance of cancer.

Promote the body's immunity against cancer: The most important thing to improve the function of the immune system is: diet, exercise and control troubles, healthy lifestyle choices can help us stay away from cancer, maintain good emotional state and appropriate physical exercise can make the body The immune system is at its best, and it is also good for preventing tumors and preventing other diseases. In addition, studies have shown that appropriate activities not only enhance the body's immune system, but also reduce the incidence of colon cancer by increasing the peristalsis of the human intestinal system. Here we mainly understand some of the problems of diet in preventing tumors.

Human epidemiology and animal studies have shown that vitamin A plays an important role in reducing the risk of cancer. Vitamin A supports normal mucosa and vision. It directly or indirectly participates in most of the body's tissue functions. Vitamin A is present in animal tissues. In the liver, whole eggs and whole milk, the plant is in the form of -carotene and carotenoids, which can be converted into vitamin A in the human body. Excessive intake of vitamin A can cause adverse reactions in the body and -carrot This is not the case with carotenoids, and the low vitamin A content in the blood increases the risk of malignant tumors. Studies have shown that those with low levels of vitamin A intake in the blood increase the likelihood of lung cancer, while those with low blood levels in smokers Levels of vitamin A ingestors have the potential to double lung cancer. Vitamin A and its mixture can help remove free radicals in the body (free radicals can cause damage to genetic material), and secondly stimulate the immune system and help differentiate cells in the body. Ordered tissue (while the tumor is characterized by disorder), some theories suggest that vitamin A can help early carcinogens Invasion mutated cells become reversed the occurrence of the normal growth of cells.

In addition, some studies suggest that supplementation with -carotene alone does not reduce the risk of cancer, but rather increases the incidence of lung cancer. However, when -carotene binds to vitamin C, E and other antitoxin substances, its protective effect. It is shown, because it can increase free radicals in the body when it is consumed by itself. In addition, there are interactions between different vitamins. Both human and mouse studies have shown that the use of -carotene can reduce 40% of vitamins in the body. At E-level, a safer strategy is to eat different foods to maintain a balanced vitamin to protect against cancer, as some protective factors have not been discovered so far.

Pediatric rhabdomyosarcoma complications Complications, cerebral snoring, urinary tract obstruction, urinary tract obstruction

Rhabdomyosarcoma of the head and neck may have blindness, ophthalmoplegia, cranial nerve spasm and meningeal irritation, airway obstruction, asphyxia and nosebleeds, otitis media, etc.; genitourinary rhabdomyosarcoma may have urinary tract obstruction, hematuria, intestinal obstruction Etc. Rhabdomyosarcoma of the extremities and trunk may have spinal cord compression and neurological symptoms. Rhabdomyosarcoma in other areas may have heart failure or arrhythmia; in addition to the primary disease, rhabdomyosarcoma may be transferred to the lungs, bones, bone marrow, lymph nodes, brain , liver and breast, etc., the corresponding symptoms can appear.

Symptoms of rhabdomyosarcoma in children Common symptoms Muscle fiber size is not weak, anorexia, Sichuan pattern

Rhabdomyosarcoma can occur in any organ or part, mostly by the parents of the child first found asymptomatic mass. In the case of diffusion, the patient may have fever, anorexia, weight loss, pain and weakness. Tumors in different parts may still have characteristic symptoms and signs. The tumor occurs in two age groups: 2 to 4 years old and 12 to 16 years old. Recent studies by the IRS have shown that the average age is 5 years (0 to 20 years), 66% of patients are less than 10 years old, 6% are younger than 1 year, and the male to female ratio is 3:2. The most common sites of onset are the head and neck (35%), the genitourinary system (26%), and the extremities (19%).

1. Clinical features

Different parts of rhabdomyosarcoma have their clinical features:

(1) Head and neck: Head and neck tumors can be divided into three types according to the location of the eyelids, around the meninges and around the meninges. Rhabdomyosarcoma in the orbit can cause ocular bulging, conjunctival edema, or eyelid and conjunctival lumps. Late stage may be blind, eye muscle paralysis, or both. Tumors around the meninges often erode the skull, causing cerebral palsy and meningeal irritation. Nasopharyngeal tumors can cause changes in sound, airway obstruction, asphyxia, and nosebleeds. Paranasal sinus tumors have pain, increased nasal secretions, and nosebleeds. Tumors in the middle ear and mastoids can be polypoids protruding from the ear, and can have otitis media and facial nerve spasms. Depending on the location of the original site, 5% to 20% of cases have cervical lymph node metastasis. The prognosis of orbital tumors is the best, while the peri-membrane tumors have the worst prognosis. The tissue types of head and neck rhabdomyosarcoma are mostly embryonic. The incidence of nasopharyngeal carcinoma and rhabdomyosarcoma of the nasopharynx is very similar, but nasopharyngeal carcinoma is more common in older children, with higher rate of cervical lymph node metastasis and poor prognosis.

(2) genitourinary system: genitourinary tumors can be manifested as urinary tract obstruction, hematuria or both, and pelvic mass can cause abdominal pain or intestinal obstruction. Vaginal, cervical, and uterine tumors may have vaginal secretions. Para-testicular tumors are usually unilateral, painless scrotal masses, occasionally with retroperitoneal masses, and more secondary to lymphatic spread, accounting for 27%.

(3) Limbs and trunks: Tumors in the limbs and trunk are characterized by masses, and in some patients lymph node metastases (12%). Chest tumors can compress breathing. Paraspinal tumors can have spinal cord compression and neurological symptoms.

(4) Other parts: retroperitoneal rhabdomyosarcoma can be very large, leading to abdominal pain, digestive tract or urinary tract obstruction. Gastrointestinal and biliary tumors are rare, but if they occur, they appear as digestive or biliary obstruction. Cardiac tumors generally have congestive heart failure or arrhythmia. Another rare site of the disease is the trachea and lungs.

2. Tumor subtypes

The National Cancer Institute (NCI) has proposed the use of all available diagnostic methods to determine tumor subtypes in combination with clinical conditions.

(1) Embryonic type: The most common type of rhabdomyosarcoma tissue is embryonic, consisting of fusiform striated muscle cells, small round cells with eosinophils and longitudinal stripes. The age of good hair is under 8 years old. 80% of urinary rhabdomyosarcoma, 60% of head and neck, and 50% of other parts (excluding limbs and trunk) belong to this type. The embryonic form of the spindle cell is mainly found in the lateral testicular rhabdomyosarcoma, occasionally seen in the superficial part of the head and neck, and its prognosis is very good.

(2) grape cluster-like sarcoma: another type of embryonic rhabdomyosarcoma, good in the internal organs of the internal organs, such as the vagina, nasopharynx and biliary tract. The polypoid-like structure consists of a mucus matrix centered on round and fusiform cells and surrounding small round cells. The age of the predile is less than 4 years old and the prognosis is best.

(3) acinar type: is the second common rhabdomyosarcoma, second only to embryonic type. Most commonly found in the limbs and trunk, composed of large round cells with eosinophils. Substantial subtypes have the same cellular structure but lack a vesicular shape. The prognosis is poor.

(4) Polymorphic or adult type: polymorphic or adult rhabdomyosarcoma is the least common in children. It is characterized by large pleomorphic cells and multinucleated large cells, most commonly seen in the limbs and trunk.

(5) Sarcoma: Undifferentiated sarcoma is most common in the limbs, head and neck, and the prognosis is very poor. There is also a soft tissue type of rhabdomyosarcoma that can also be found in children, which cannot be classified by conventional methods, collectively referred to as sarcoma, and the type is to be determined.

Examination of pediatric rhabdomyosarcoma

Do blood routine, liver, kidney function, urine analysis, bone marrow puncture and other laboratory tests, head and neck lesions to do cerebrospinal fluid test, children with rhabdomyosarcoma have no specific plasma or urine markers.

Immunohistochemistry can use antibodies against skeletal muscle and myogenic protein to display striated muscle components in the tumor, antidesmin, multispecific actin, and myoglobin D (MyoD) are the most sensitive markers. , vimentin, myoglobin, dystrophin, cytokeratin, creatine kinase M and B, S100 and neuron specific enolase are used for further differential diagnosis, myoglobin D expression in myogenic The conversion of precursors into muscle cells is important, and in rhabdomyosarcoma this process is inhibited.

Through reverse transcriptase polymerase chain reaction (PCR) and fluorescence in situ hybridization, the diagnosis of rhabdomyosarcoma can reach molecular genetic level and is of guiding significance for the treatment. 2,13q35-q14 gene is found in acinar rhabdomyosarcoma. The site was interrupted, and a tumor growth inhibitory gene was found on chromosome 11 in embryonic rhabdomyosarcoma.

Deoxyribonucleic acid (DNA) content (or ploidy) also has a certain diagnostic value. Shapiro studies have shown that the embryonic type is high-ploid, the acinar type is mainly tetraploid, 37 unresectable rhabdomyosarcoma, 8 All of the diploid children died, while 10 of the 12 high-ploid tumors survived (P < 0.0001), but the results lacked further proof.

Because of the above-mentioned biological, immunological, and cytological diagnostic methods that play an important role in prognostic judgment and treatment, surgeons must obtain enough tumors to ensure that the diagnosis is correct.

CT, MRI can locate the tumor and its invasion to the surrounding area, bone scan can find bone lesions, CT can see liver, brain, heart and lung metastasis or not, head and neck lesions should be CT or MRI, and cerebrospinal fluid test Spinal infiltration of the paraspinal tumor can be observed by MRI.

Diagnosis and diagnosis of rhabdomyosarcoma in children

diagnosis

Diagnosis should be carefully examined for the primary site of the disease and surrounding lymphoid tissue, to do a variety of laboratory tests and auxiliary examinations, CT, MRI can locate the tumor and its invasion to the surrounding. Bone scan can detect bone lesions, CT can see liver, brain, heart and lung metastasis or not, CT or MRI examination of head and neck lesions, and cerebrospinal fluid test. Spinal infiltration can be observed by MRI.

Rhabdomyosarcoma is a tumor lesion that differentiates into striated muscle and can occur in any part of the mesenchymal tissue, including those without striated muscle components. In 1958, Horn and Enterline first proposed the diagnostic criteria for rhabdomyosarcoma. With the development of biotechnology, such as the application of immunophenotyping, cellular and molecular genetics, it has been modified in some aspects, and the content is even more Detailed, more prognostic value.

The 5-year survival rate is closely related to the type of tissue: grape type 95%, polymorphic type 75%, embryo type 66%, acinar type 54%, undifferentiated type 40%.

Differential diagnosis

It occurs in different parts and is differentiated from the tumors in the corresponding parts. It is mainly diagnosed by pathological examination.

1. Embryonic rhabdomyosarcoma Histopathology There are round or fusiform cells in the mucus matrix. The nucleus is round or oval, the chromatin is loose and the nucleolus is unclear, and the cytoplasm is abundant. When the nucleus is on the side of the cell, it is often sputum-like. Vertical or horizontal stripes can sometimes be seen in spindle cells.

2. Acinar rhabdomyosarcoma Histopathologically narrow connective tissue trabeculae divide the tumor cells into acinar-like cells, one or several layers of tumor cells attached to the trabeculae, and a few tumor cells floating in the central cavity. Large multinucleated cells can be seen with horizontal or vertical lines visible. The previous description focuses on the acinar-like structure that emphasizes the megakaryocyte, polymorphism, and coarse chromatin of tumor cells. Cytogenetic ectopic t(2;13)(q35;q14) is present, and the analysis of its fracture region can be distinguished from Ewing's sarcoma.

3. Polymorphic rhabdomyosarcoma Histopathology: basically a spindle-shaped tumor cell with pleomorphism. Long-shaped ribbon cells can be seen, and the cytoplasm is rich, and the horizontal stripes, that is, the muscle fibers, can be seen in the bright red cytoplasm. In addition, it can be seen that atypical stellate cells are more common in nuclear division; round cells, cytoplasmic strong eosinophilic, sometimes nuclear deviation; tubular cells, myofibrils located in the central area under the capsule, lightly stained nuclear single or Multiple, visible nuclear pericy; fusiform cells are more common, the length of the cells are different, the cytoplasm is rich, pale acidophilic staining, often contains myofibrils and can be seen in various forms of multinucleated cells.

4. Grape-like rhabdomyosarcoma Histopathology, there is a cell infiltration band under the mucosa, the cells are short spindle-shaped cytoplasm, and parallel with the mucosa. Rhabdomyosarcoma is poorly differentiated, and it is often necessary to use immunostaining to show that fibrin-binding protein and myosin-positive characteristics are used for the diagnosis of ultrastructure to show the presence of Z-band muscle fibers.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.