Peripheral T-cell and NK-cell neoplasms: an integrated approach to diagnosis.

Peripheral T-cell and NK-cell neoplasms account for only 10% of all non-Hodgkin's lymphomas, but they commonly pose great difficulties in diagnosis and classification. This article addresses the distinction between peripheral T-cell or NK-cell lymphoma and reactive lymphoid hyperplasia, the importance of recognition of the T-cell or NK-cell lineage for a lymphoma; and the importance of classification of a peripheral T- or NK-cell lymphoma. To solve these problems, it is imperative to adopt an integrated approach, taking the clinical features, morphologic findings, immunohistochemical profile, and/or genetic data into consideration.