The tumors are of tufts of capillary-sized vessels in lobules that are scattered in the skin, and that sometimes reach into the subcutaneous tissue, and have lymph vessels on the periphery. Their growth is slow to begin with, and progresses to a stable size. They show a high rate of spontaneous regression, particularly in congenital and early-onset cases. They typically have a deep nodular component sometimes extending into the subcutaneous tissue, fascia, and muscle, and can sometimes be painful. Tufted angiomas are associated with arteriovenous malformations.The origin of tufted angiomas is not clear but markers on the cells suggest a possible derivation from the endothelial cells of lymph vessels. They are also associated with the local secretion of growth factors that affect angiogenesis and promote the development of vascular lobules. Borderline
Kaposiform hemangioendotheliomas (KHEs) are borderline, locally destructive vascular tumors. They are named after their resemblance to the lesions of Kaposis sarcoma. KHEs are described as locally destructive because they can infiltrate underlying muscle and fat. They are often seen to overlap with tufted angiomas (TAs) but TAs may be a milder, benign counterpart.KHEs show as a red or purple expanding mass of soft tissue, found mostly in infants. Under the microscope KHE is characterised by nodules of tumor-like spindled endothelial cells. Unlike infantile hemangiomas, KHEs have a high mortality rate. Both KHEs and TAs are unique in that they carry the risk of the development of Kasabach–Merritt syndrome. Malignant
Malignant vascular tumors are rare, and include angiosarcomas, and epithelioid hemangioendotheliomas. Other types are  hemangiopericytomas, and lymphangiosarcomas.
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