Vascular lesions of bone constitute a spectrum of pathologic entities. These range from congenital vascular malformations, that is, errors of morphogenesis with nonproliferative capacity, which growth is parallel with growth of the patient (such as angiomatosis), to benign neoplasms that may be present at birth, and to highly malignant tumors that widely metastasize and have a low survival rate (such as angiosarcoma). In the past decade, immunohistochemistry studies have been conducted in attempts to discriminate between malformations and true tumors. The formers have been found to be negative for WT1 (a transcription factor initially isolated from a hereditary Wilms tumor encoded by the so-called Wilms tumor 1 [WT1] gene) and GLUT1 (an erythrocyte-type glucose transporter protein not present in normal vasculature and vascular malformations but found at sites of blood-tissue barriers and in vascular tumors). Furthermore, some investigators found somatic mutations in genes coding for the receptors VEGFR2 and VEGFR3 of the vascular endothelial growth factors, which play an important role in angiogenesis and vascular formation.

Benign vascular lesions are of either endothelial or pericytic origin. The first group includes hemangiomas, cystic angiomatosis, Gorham disease of bone, lymphangiomas, and lymphangiomatosis. The second group includes glomus tumor and its variants, glomangioma and glomangiomyoma. Hemangiomas are classified according to the type of vessels in the lesion as capillary, cavernous, venous, and mixed. Diffuse involvement of bones by hemangiomatous lesions is defined as hemangiomatosis or angiomatosis. When bone is extensively involved, particularly if there is formation of intramedullary cystic lesions, the term cystic angiomatosis is applied. Gorham disease of bone, also known as massive osteolysis, phantom bone disease, or disappearing bone disease, is characterized by progressive, localized bone resorption, probably caused by multiple or diffuse cavernous hemangiomas or lymphangiomas of bone or both. Lymphangioma is a rare disorder consisting of the lesion composed of sequestered, noncommunicating lymphoid tissue lined by lymphatic endothelium. Glomus tumor and its variants are rare lesions composed of rounded uniform cells often arranged in a brickwork-like pattern.

The locally aggressive and malignant tumors are quite uncommon and are mostly of endothelial origin, such as hemangioendothelioma and angiosarcoma. The existence of hemangiopericytoma as a distinct tumor is still a matter of debate. World Health Organization (WHO) classifies this lesion in the category of fibrous tumors changing its name to “myopericytoma.”