Intravascular large B-cell lymphoma (ILBCL), also referred to as angiotropic large-cell lymphoma,:376 angiotropic large-cell lymphoma, intralymphatic lymphomatosis,:376 intravascular lymphomatosis, and, less specifically, intravascular lymphoma and malignant angioendotheliomatosis:376 is a rare form of lymphoma.aggressive: Sézary disease Intravascular large B-cell lymphoma (ILBCL), also referred to as angiotropic large-cell lymphoma,:376 angiotropic large-cell lymphoma, intralymphatic lymphomatosis,:376 intravascular lymphomatosis, and, less specifically, intravascular lymphoma and malignant angioendotheliomatosis:376 is a rare form of lymphoma. ILBCL presents with variable non-specific symptoms, the most common of which are rash, neurologic symptoms, and B symptoms, such as fever, weight loss, and night sweats.:376:742 It may be difficult to diagnose in a timely manner. The disease is rare, with a prevalence of 1 person per million. There are two forms of the disease; a Western form that has a cutaneous variant, and a form that is more common in east Asia. The diagnosis is established by the examination of tissue under the microscope (i.e. biopsy or autopsy) and immunohistochemical stains. Intravascular lymphomas have a large cell morphology, i.e. the malignant cells are two or more times the size of a normal lymphocyte, and typically have a prominent nucleolus. Most intravascular lymphomas are of the B-cell lineage. Most cases of intravascular lymphoma are caused by the infiltration of B-cells into the lumens of small blood vessels. Intravascular lymphoma is an aggressive cancer that is rapidly fatal without treatment, but which can respond well to combination chemotherapy, usually some combination of Rituximab, Cyclophosphamide, Adriamycin, Oncovin, and prednisone (R-CHOP). It used to be known as malignant angioendotheliomatosis, as it was once thought to arise from the endothelium.