Anaplastic Large Cell Lymphoma

A Critical Reappraisal

Abstract

A revised concept of anaplastic large cell lymphoma (ALCL) on both historical and practical grounds is presented. The main histological findings are illustrated with special reference to the cytological spectrum that is characteristic of the tumor. The phenotype is described in detail. The expression of the ALK protein as well as the chromosomal abnormalities that sustain it, are discussed along with potential pathogenetic implications. The clinical features of ALCL are presented by underlying the dramatic difference in terms of response to therapy and survival between ALK-positive and ALK-negative forms. The possibility of limiting the term ALCL to systemic ALK⁺ anaplastic tumors with T/null phenotype is considered.