Myeloperoxidase-positive intravascular large B-cell lymphoma

Intravascular large B-cell lymphoma (IVLBL) is an uncommon form of non-Hodg kin lymphoma that is also known as malignant angioendotheliosis, intravascu lar lymphomatosis, and angiotropic large-cell lymphoma. The disease is char acterized by a bizarre population of neoplastic cells, which are found syst emically within vascular lumina. Although originally thought to be a neopla stic process of the endothelial cells, it has since been demonstrated, by m olecular techniques and immunohistochemistry, that the neoplastic cells are of lymphoid origin. The differential diagnosis of these lesions includes g ranulocytic sarcomas that can be distinguished from IVLBL or other lymphoma s by the presence of immunohistochemical positivity for myeloperoxidase. We describe a patient with a history of a myelodysplastic syndrome who subseq uently developed IVLBL, which demonstrated immunohistochemical positivity f or myeloperoxidase. To our knowledge, this represents the first case of a m alignant lymphoma to demonstrate such findings.