Angiocentric lymphomas (lymphomatous vasculitis).

Angiocentric lymphomas are a heterogeneous spectrum of hematolymphoid malignancies that share a particular histologic characteristic, namely, an angiocentric or perivascular growth pattern. They include a variety of T-, B-, and natural killer-cell derived lymphomas that digress in many clinicopathologic features, immunophenotype, and prognosis. The term angiocentric lymphomas was initially used to refer to natural killer and natural killer-like T-cell lymphomas that show a prominent angiocentric growth pattern. With better immunophenotypic and molecular characterization together with evolving knowledge regarding their biology and pathogenesis, these lymphomas have now been reclassified. Apart from morphology, many features pertinent to the diagnosis of natural killer and natural killer-like T-cell lymphomas are shared by other peripheral T-cell and B-cell lymphomas, and by a subset of leukemias. The salient clinicopathologic features of natural killer and natural killer-like T-cell lymphomas together with the inherent difficulty of their identification and an integrated approach to their diagnosis are outlined in this article.