Major Subtypes of Mature T- and NK-Cell Neoplasms

This chapter is focused on answering frequently asked questions in the workup of the most common T-cell and NK-cell neoplasms. Since cutaneous T-cell lymphomas and T-cell lymphomas of the intestine are expanded upon elsewhere, this text primarily involves the morphologic, immunophenotypic, and molecular evaluation of nodal, leukemic, and a few extranodal entities. While T- and NK-cell lymphomas are relatively rare, within this umbrella, angioimmunoblastic T-cell lymphoma, anaplastic large cell lymphoma, and peripheral T-cell lymphoma, not otherwise specified, are still encountered and regularly suspected in a general surgical pathologist’s busy practice. These are also areas in which some alterations to the classification have occurred over the last few years. We summarize the key points here and how they apply to the clinical workup of these neoplasms.