Infantile hemangioma is the most common benign tumor in infants and children, and the incidence varies among reports. Hemangiomas can be distributed throughout the body, but are relatively more common in the face and neck. The incidence ratio of male to female is very different, about 1:3-5. Pathogenesis The pathogenesis of hemangioma is still unclear, and the proliferation and regression phenomena are still not well understood. There are various theories about hemangiogenesis: the theory of angiogenic cells, the theory of placental origin, the theory of imbalance in angiogenesis, the theory of mutations in cytokine regulatory pathways, the theory of defects in developmental regions, the theory of non-endothelial cells in hemangioma formation, and the theory of immunity and inflammation. In contrast, the regression of hemangiomas is thought to be related to the following factors: altered cellular composition, altered expression of cytokines, and apoptosis. With the accumulation of epidemiological, basic biological and cytological information characteristic of hemangiomas, there have been significant advances in the study of the mechanisms of their growth and regression. The lack of ideal animal models has hindered the depth of research. The current research hotspots are still focused on angiogenic cells, placental implantation, dysregulated angiogenesis and developmental defects, but little research has been done on the mechanism of hemangioma regression. Future research should focus on this, which will provide new ideas for early prevention of hemangioma, specific intervention therapy, and open new horizons for the study of vascular developmental biology. Clinical manifestations The natural course of hemangioma can be divided into: the proliferative phase, the stable phase and the receding phase. Some of them grow very slowly, while others can invade large areas of normal tissues and organs within a few weeks, and in severe cases, almost the entire face can be involved, causing serious deformities and dysfunction. The typical appearance of the lesion is a bright red elevated tough mass with clear boundaries, which does not recede when pressed. If the lesion is located entirely in the subcutaneous tissue, it appears as a subcutaneous bluish-purple mass without bright red lesions. When two or more lesions appear in different parts of the body, they are called multiple hemangiomas. After about one year of proliferation, the lesions stagnate in growth and enter a stable phase. The regression phase is indicated when the central part of the lesion starts to gradually turn white and fuse and expand, and the mass starts to become soft. After regression, pigmentation, scar formation, capillary dilatation, and fibrous and fatty deposits may remain. Treatment Principles: Treatment should be safe, fast-acting, non-invasive (or minimally invasive), and free of secondary deformities. Traditional treatment: 1. Hormonal therapy: Corticosteroids can be taken orally or injected intra-tumorally to treat hemangiomas. Oral medication is mainly used for larger or rapidly proliferating lesions, while local injection is an option for very limited and small lesions. Early efficacy is demonstrated by the cessation of tumor growth rather than immediate regression. Treatment leads to early stabilization and regression of the hemangioma, as evidenced by the softening of the tumor, the beginning of surface whitening, the appearance of skin folds, and the cessation of growth. The effective rate is about 85%. However, it is easy to appear complications such as obesity, especially affecting the use of vaccine. 2.Local treatment with anti-tumor drugs: Local injection of anti-tumor drugs is also widely used in clinical application, among which the most reported is Pingyangmycin, which also has obvious therapeutic effect on hemangioma in proliferation stage. However, if the concentration is too high, it may lead to fibrosis or necrosis of normal tissues at the injection site, especially for superficial lesions. Therefore, treatment should not be aimed at rapid “cure”, but rather at inhibiting proliferation and ensuring that the treatment does not cause a variety of adverse reactions affecting the final appearance, including pigmentation changes and scar growth, the most serious complications being allergy and death! 3.Radiotherapy (including radionuclide dressing treatment): The vascular endothelial cells of proliferating hemangioma are in a childish proliferative state and have high sensitivity to radiotherapy. After treatment, angiogenesis stops, capillaries become degenerative and occluded and appear similar to fading performance, so the effect is more reliable and objective. However, complications such as local skin pigmentation changes, especially hypopigmentation, scar formation and capillary dilatation, may occur, leading to an impact on the final effect of the skin after regression. Excessive doses of radiation therapy can even lead to complications such as blockage of bone growth centers, deep tissue damage and chronic radiation dermatitis. At present, the application has been less. 4, laser treatment: the principle is mainly dependent on the selective photothermal effect of the laser. Selective photothermal action refers to the use of capillary hemoglobin in the vicinity of 580nm wavelength absorption peak and the surrounding tissue absorption of less heat, as well as the use of the principle of inter-pulse heat dissipation, to achieve a higher selective thermal coagulation of hemoglobin, ultimately leading to vascular occlusion. The pulsed dye laser (585 nm) is preferred for treatment, and secondary scar formation and pigment changes are generally less likely to occur. However, because the actual penetration capacity of visible light in this wavelength range is weak, often less than 1.5 mm, it cannot act on the whole lesion of most strawberry hemangiomas, and thus cannot be used as the main treatment method, and is only used for superficial, small and slow-growing or stopped partial strawberry It can only be used for superficial, small, slow-growing, or partially stopped strawberry hemangiomas, and is based on the premise that no scar or permanent pigmentation changes will be formed, so this requirement can only be met by experienced personnel in suitable cases at present. In addition, treatments performed by non-selective photothermal action such as Nd:YAG and CO2 laser should tend to be eliminated, because when the lesion subsides, depressed scarring may be seen after the treatment. Some new treatments that have emerged in recent years: 1. Oral propranolol (beta-blocker): Oral propranolol for infantile hemangioma was first used by a French doctor in 2008, and then became popular worldwide. For severe infantile hemangioma oral administration of this drug can make the proliferating hemangioma appear obvious receding in a short period of time, and it has gradually become the first-line treatment drug for this disease, but its adverse reactions and so on need to be confirmed by large samples and multi-center clinical studies, and neither the FDA in China nor the FDA in the United States has approved the legality of its treatment at present, but the treatment effect is indeed remarkable. 2.For superficial infantile hemangioma: Recently, topical imiquimod cream (a new type of immunomodulator) is used to inhibit the proliferation of small and superficial lesions and accelerate the regression, but to prevent the skin of the tumor surface from ulcerating and leaving a scar. For the same case, some people use topical application of timolol maleate eye drops to achieve better therapeutic effect and less side effects. 3.Surgical treatment: It is mainly used in the following two cases: (1) When the hemangioma is located in more special parts, such as upper and lower lids, external nose or lips, which may cause obvious functional disorders, such as amblyopia, strabismus, poor breathing or difficulty in eating, surgery can be considered to remove all or part of it to improve the function. (2) Skin laxity, fibrofatty deposits and tissue and organ displacement left after the hemangioma subsides can be rectified surgically. Observation . Follow-up: For hemangiomas with very insignificant proliferation or those that have entered the stable or receding stage, do not be too aggressive in treatment. Because natural regression leaves an essentially normal skin structure that is sometimes even difficult to detect after regression, even if there is residual loose surface skin, it is easily corrected by later plastic surgery. In contrast, if non-specific and more damaging treatments are chosen, they may not only be ineffective in reducing the lesion, but also cause adverse consequences such as scarring or pigmentation changes. Therefore, follow-up is an ideal option for fading lesions that are inconvenient to surgery or have a poor postoperative appearance, as well as for hyperplastic hemangiomas that are expected to grow more slowly or even have become nearly quiescent. However, families of children are generally anxious and not easy to accept, so careful explanation of the course of the disease and prognosis is needed to gain understanding. To sum up, the most important point in the treatment of infant hemangioma is accurate diagnosis, and only accurate diagnosis can lead to reasonable and appropriate treatment.