Anaplastic large cell lymphoma: A clinicopathologic analysis

The clinicopathologic features of anaplastic large cell lymphoma (ALCL) are reviewed. ALCL is a heterogeneous group of tumours, and histologic examina tion alone is not adequate in providing useful prognostic information. Howe ver, using a combination of clinical, phenotypic, and genotypic features, s everal distinct clinicopathologic entities have been identified. A subset o f ALCL as presently defined is characterized by a balanced translocation, t (2;5)(p23;q35), resulting in a novel fusion protein (NPM-ALK) that can be r eadily detected by immunohistochemical methods using antibodies against the ALK protein. Detection of ALK protein, along with other methods for demons trating the t(2;5), has assisted in identifying a distinct biologic entity within the heterogeneous group of ALCL with significant prognostic implicat ions. It is important to separate these from cases of ALK-negative ALCL, wh ich have a poorer prognosis, and cases of primary cutaneous ALCL, which hav e an excellent prognosis. Copyright (C) 1999 John Wiley & Sons, Ltd.