Anaplastic Large Cell Lymphoma: a Review

Overview

Anaplastic large cell lymphomas (ALCLs) represent a heterogeneous group of malignant lymphoproliferativediseases. Most of the cases are of T-cell line with a loss of cell surface receptors butwith a production of cytotoxic cytoplasmatic granules – immunohistochemically (IHC) positiveperforin, granzyme B, and TIA-1. The diagnostics of ALCL is based on morphological findings andresults of IHC, which further stratify ALCLs to basic immunophenotypes according to ALK (anaplasticlymphoma kinase) protein expression – ALCL CD30+ ALK+ and ALCL CD30+ ALK-. Themorphological investigations are supplemented by karyotyping and/or by a demonstration of breakpointat 2p23 harboring ALK gene (FISH), and by molecular detection of chimeric genes characteristicof ALK+ lymphomas (NPM-ALK, ATIC-ALK, TPM3-ALK, TFG-ALK, and some even rarerrearrangements). Molecular diagnostics is important in monitoring minimal residual disease. Assome of the characteristic molecular changes were demonstrated in healthy individuals and inHodgkin’s disease by quantitative PCR, the validation of these findings demands further studies.ALK protein positive ALCLs affect patients in age categories up to the third decade, whereas ALKprotein negative cases occur in older patients with an average age of 60 years. Both subgroups oflymphomas are aggressive but ALK+ lymphomas react well to systemic treatment, and havea more favorable prognosis. Primary skin ALCLs belong to a group of T-cell lymphoproliferativediseases of the skin and have, in the majority of cases, a favorable course without generalization.

Key words:
anaplastic large cell lymphoma – ALCL – ALK protein – chromosomal translocations –diagnostics