A variety of vascular disorders may affect the lymph nodes, resulting in ischemic infarction, benign vascular prolife-rations, or malignant vascular neoplasms.

Lymph nodes are well vascularized, and therefore ischemic infarction is uncommon. Occasional obstruction of blood flow may occur in the case of compression by tumor, vascular embolization and thrombosis, or surgical intervention in the region (see Chapter 47).

Non-neoplastic angiomatosis in lymph nodes arising in the high endothelial venules of the paracortex is a characteristic feature of angioimmunoblastic lymphadenopathy (see Chapter 75), Castleman lymphadenopathy (see Chapter 42), Kimura lymphadenopathy (see Chapter 35), HIV lymphadenitis, type C (see Chapter 15), and others. Bacillary angiomatosis, a tumor-like proliferation of capillaries and arterioles, is caused by a microorganism named Bartonella henselae (see Chapter 18). A peculiar process of lymph node angiomatosis is the vascular transformation of sinuses in which the vasoproliferative process selectively involves the nodal sinuses, expanding through subcapsular, intermediate, and medullary sinuses without involvement of the lymphoid parenchyma or the lymph node capsule (see Chapter 48). Some of these conditions may be related to the release of angiogenesis factors by activated lymphoid cells. The importance of vascular lymphadenopathies is that they can be confused with the vascular neoplasms of lymph nodes (see Chapters 85 and 86).