<unk>  (IVL) are rare cancers in which malignant lymphocytes proliferate and accumulate within blood vessels. Almost all other tyes of<unk> involve the proliferation and accumulation of malignant lymphocytes in lymph nodes, other parts of the lymphatic system (e.g. the spleen), and various non-lymphatic organs (e.g. bone marrow and liver) but not in blood vessels. IVL fall into three different forms based on the type of lymphocyte causing the disease.<unk>  large B-cell<unk> (IVBCL), which constitutes ~90% of all IVL, is a<unk> of malignant B-cell lymphocytes as classified by the World Health Organization, 2016. The remaining IVL types, which have not yet been formally classified by the World Health Organization, are defined based mainly on case reports; these IVL are 1)<unk>  NK-cell<unk> (IVNKL) in which the malignant cells are a type of T cell lymphocyte termed natural killer cells (NK-cells) and 2)<unk>  T-cell<unk> (IVTL) in which the neoplastic cells are primarily, if not exclusively, a type of t-cell termed cytotoxic T-cells. Because of their similarities and extreme rarities, IVL<unk>  caused by NK-cells and cytotoxic T-cells are often grouped together under the term<unk>  NK/T cell<unk>  (IVNK/TL). The malignant cells in IVNK/TL are typically infected with the Epstein-Barr virus suggesting that these<unk>  are examples of the Epstein-Barr virus-associated lymphoproliferative diseases. Since infection with this virus is rarely seen in IVBCL, this form of IVL is not typically regarded as one of the Epstein-Barr virus-associated lymphoproliferative diseases.<unk>  large B-cell and<unk>  NK/T cell IVL are typically very aggressive<unk>  that afflict middle-aged and elderly adults. At the time of diagnosis, they accumulate within small-sized and medium-sized but not large-sized blood vessels of the skin, central nervous system, and, less frequently. virtually any other organ system. Unlike most<unk> , however, they generally do not accumulate or infiltrate lymph nodes. All of the IVL are frequently associated with systemic B symptoms such as fever and weight loss, as well as symptoms related to the other organs in which they accumulate in blood vessels, constrict blood flow, and thereby cause severe damage due to infarction, i.e. damage due to the loss of blood flow. Historically, most cases of the<unk>  responded very poorly to standard chemotherapy regimens that were used to treat other types of the B-cell<unk> . With few exceptions, these<unk>  progressed very rapidly. More recently, however, the addition to these chemotherapy regimens of the immunotherapy agents, Rituximab, which acts to kill B-cells, has greatly improved their effectiveness and thereby the prognosis of the most common form of these diseases, the<unk>  B-cell<unk> . Unfortunately, no such agent that is directed against NK-cells or cytotoxic T-cells has yet been reported to be useful in treating these two types of the<unk>  B-cell<unk> .
Intravascular lymphomas
Meningioangiomatosis
Capillary aneurysms
Mycotic aneurysm
Systemic vasculitides
Microvasculitis
Nodular vasculitis
Systemic vasculitis