Hemangiomas are composed of a large number of proliferating blood vessels. In the early embryonic period, the primitive vasculature is a tube composed solely of endothelial cells, which form a dense network in the middle of the mesenchyme. Later, with the development of the organs, the primitive vascular network gradually differentiates into many vascular and lymphatic plexuses associated with the organs. There are three stages in the embryonic development of blood vessels: the plexiform stage, the reticular stage and the trunk stage. If a disorder or abnormality occurs during the normal development of a particular stage, a malformation of the normal developmental pattern of that stage may occur. In the plexiform stage, some capillaries will produce capillary hemangioma if they stop developing; in the reticular stage, cavernous hemangioma can be manifested if the enlarged blood vessels gather into clusters and tend to merge together. Zhou Hammer, Department of Hand and Microsurgery, Shenzhen Hospital, Peking University Under the microscope, hemangiomas are of various morphologies, but the basic structure is similar, i.e., there are well-developed vascular-like tissues, such as the outer layer, middle layer and endothelium, with lumen diameters ranging from 1 to 10 mm, and there is connective tissue as the stroma between the blood vessels. 1.Capillary hemangioma tumor is composed of a large number of intertwined and dilated capillaries. It is characterized by bright red or purplish-red plaques. It is flush with the skin surface or slightly elevated, with clear boundary, irregular shape and different sizes. When the tumor is pressed by finger, the color recedes; after the pressure is lifted, the color is restored. 2.Cavernous hemangioma consists of enlarged blood vessel cavity and blood sinus lined with endothelial cells. The blood sinus is of different sizes, like spongy structure, and the cavity of sinus is full of venous blood, which traffic with each other. It appears as a soft, slow-growing mass with no conscious symptoms. When the head is in a low position, the tumor expands due to blood congestion, and the mass returns to its original shape when the normal position is restored. In superficial tumors, the surface skin or mucous membrane is greenish purple. In the deep part, the skin color is normal. On palpation, the mass is soft, with unclear boundary and no pressure pain. When squeezed, the mass shrinks and returns to its original size after the pressure is lifted. Trapezoidal hemangioma is mainly formed by the anastomosis of dilated artery and vein. The tumor is high up in the form of rosary or earthworm. There are sensation of movement and tremor when looking at it, and there is wind-like murmur on auscultation. If the blood-supplying arteries are completely pressed, the above motility and murmur will disappear. There are many treatment methods for hemangioma, which should depend on the type, location, depth of the tumor and age of the patient. Commonly used methods include surgical resection, radiotherapy, cryosurgery, sclerotherapy and laser irradiation.