USEFULNESS OF FLOW CYTOMETRIC IMMUNOPHENOTYPING IN THE CLASSIFICATION OF CD5-POSITIVE MATURE B-CELL NEOPLASMS

Abstract

Mature B-cell neoplasms are characterized by the presence of cells that are clonally derived from a transformed B-cell precursor arrested at distinct stages of differentiation. Any site of the lymphatic system can be the primary site of origin of the disorder, including LNs, gut-associated lymphatic tissue, skin, or spleen. The diagnosis and classification of lymphoid malignancies are extremely complex and have undergone successive changes over the past few years. Recognition of various disease entities is mandatory because of major implications for prognosis and patient management. According to WHO classification of the hematological malignancies, the diagnosis of lymphoid neoplasms relies on a multifaceted approach, and many subtypes require a combination of clinical, morphological, immunophenotypic and genetic features for a definitive diagnosis. However, the overlapping morphological and immunophenotypic features of various mature B-cell neoplasms can make diagnosis difficult. The immunophenotypic similarities to a given stage of B-cell differentiation is a relevant feature in the classification of mature B-cell neoplasms, highlighting the essential role of flow cytometry in the diagnosis and classification of these diseases. In this context, identifying CD5 on the surface of tumor cells allow to restrict the diagnostic possibilities among the several subtypes of mature B-cell neoplasms, assisting in the selection of the subsequent diagnostic methods required for a definitive diagnosis. Therefore, the aim of our study was to evaluate the usefulness of flow cytometric IPT in the classification of CD5+ mature B-cell neoplasms and to evaluate whether the inclusion of CD43, CD200, CD1d and CD160 in a conventional immunophenotypic panel could be useful to improve the diagnostic accuracy of B-cell lymphomas by flowcytometric analysis or not. This study was conducted on 62 adult patients newly diagnosed as having CD5+ mature B-cell neoplasms. They were recruited from the Hematology/Oncology unit of Ain Shams University hospitals, during the period from August 2013 till November 2015. Diagnosis was based on careful history taking and thorough clinical examination together with laboratory investigations including persistent lymphocytosis >5x109/L and BM aspirate smear morphological examination. Differentiation between various types of CD5+ mature B-cell neoplasms was attempted through multidisciplinary approach using extended flow cytometric IPT of PB and /or BM samples. Trephine and/ or LN biopsy together with FISH analysis for t(11;14) were also performed in selected cases to confirm or exclude diagnosis of various subtypes. For every case, samples assigned for flowcytometric studies were assessed with a large panel of antibodies together with CD43, CD200, CD1d and CD160 and were performed on either PB or BM samples. According to the WHO classification of B-cell neoplasms, the 62 patients were classified into: CLL group: 31 patients, 21 males (67.7%) and 10 females (32.3%) with a mean age of 60.35 ± 9.01 years, aCLL group: 5 patients, 2 males (40%) and 3 females (60%) with a mean age of 59.80± 5.59 years, B-PLL group: 9 patients, 6 males (66.7%) and 3 females (33.3%) with a mean age of 64.89 ± 6.21 years, MCL group: 10 patients, 7 males (70%) and 3 females (30%) with a mean age of 66.2 ± 9.39 years, SMZL group: 5 patients, 3 males (60%) and 2 females (40%) with a mean age of 50.4 ± 8.17 years, DLBCL group: 2 patients including one male patient at the age of 70 and one female at the age of 43.