Causes of rhabdoid tumor in children

As human living standards improve, humans have a deeper understanding of health. It should be said that with the rapid development of medicine today, human beings are gradually uncovering the truth about various diseases, thereby minimizing the impact of diseases on the quality of human life. Childhood rhabdoid tumor is a common disease in children. The incidence of this disease is very high and shows an increasing trend year by year. So what factors are related to the incidence of childhood rhabdoid tumor?

(I) Cause of the disease: This disease is a malignant tumor of soft tissue composed of rhabdomyoblasts of various degrees of differentiation. The cause of the tumor is unknown, but genetic factors cannot be ruled out.

(II) Pathogenesis 1. Staging The IRS grading of rhabdomyosarcoma is mainly based on clinical conditions, especially preoperative and intraoperative conditions, but the biological characteristics of the tumor are not reflected. Therefore, it is not an exaggeration to call it surgical pathological staging. However, the clinical classification of IRS is still widely recognized (Table 1).

In IRS, 20% of patients were in grade I, 21% in grade II, 45% in grade III, and 14% in grade IV. Compared with IRSⅡ, the number of patients with grade Ⅲ increased, which was mainly due to the decrease in the complete resection rate. For some tumors, such as those located in the pelvic area, the goal of surgery is not to completely remove them.

Among grade I patients, 42% occurred in the urogenital system excluding bladder and prostate, and 31% occurred in the limbs. 39% of grade II patients had head and neck tumors other than meninges. Among grade III tumors, 46% were head and neck tumors. Among grade IV tumors, 31% were limb tumors, 14% were perimeningeal tumors, and 41% were other types.

Lawrence, Gehan and others analyzed the IRSⅡ data and determined that the tumor location, size, range of invasion and presence or absence of local lymph node metastasis are important for the survival of children without distant metastasis. They improved the clinical classification and divided it into 4 stages (Table 2), which has now been adopted by IRS IV. This staging is mainly based on the biological characteristics of the tumor rather than the extent of surgical resection and can better predict prognosis (Table 3). In general, the primary tumor site and distant metastasis are the most valuable indicators for determining prognosis.

2. Pathological changes (1) Macroscopically: Except for embryonal rhabdomyosarcoma which is myxoid and those growing in the cavity which are polypoid, other types are fungoid, lobed or nodular. The borders are clear, there is no true capsule, the cross-section is soft, grayish white or grayish red fish meat-like, and may be accompanied by bleeding and necrosis.

(2) Under the microscope:

① Embryonic type: also called child type. It is composed of early immature developing striated myoblasts and primitive mesenchymal cells. The cells are spindle-shaped, star-shaped, oval or elliptical, sparsely arranged, with abundant mucus matrix and frequent nuclear divisions. Longitudinal myofibrils or transverse striations may be seen. This type accounts for about 2/3 of rhabdomyosarcoma.

② Alveolar type: more common in young people. It is mainly composed of small, round and oval undifferentiated myoblasts. The tumor cells are arranged in alveolar, tubular or slit-like shapes, and their morphology resembles embryonic myotubes.

(3) Polymorphic type: also called adult type. It is mainly composed of larger ribbon-shaped, tennis racket-shaped polymorphic cells, megakaryocytes and multinucleated tumor giant cells. The cell nuclei are irregular, darkly stained, and have frequent nuclear divisions.

If diagnosis is difficult, immunohistochemistry examination can be performed. The positive rates of myoglobin, desmin, and vimentin were 72.2%, 55.5%, and 88%, respectively. Myosin can reach 100%.