Immunophenotyping of lymphoproliferative disorders: state of the art

Value of multi-parameter flow cytometry immunophenotyping in T/NK-cell neoplasms in cytology specimens: A retrospective study in Chinese patients

BACKGROUND

Innate limitations of morphological diagnosis of T/NK-cell neoplasms mean that they can be misdiagnosed or missed, especially when mixed with a variety of benign and reactive conditions. The aim of this study was to investigate the application value of multiparameter flow cytometry immunophenotyping (MFCI) in screening and diagnosing T/NK-cell neoplasms with cytology specimens.

MATERIAL AND METHODS

The clinical and pathological characteristics of 1028 newly diagnosed cases from Fudan University Shanghai Cancer Center who provided a cytology specimen between June 2010 and January 2016 with correlated histology diagnosis and clinical confirmation were retrospectively reviewed. MFCI was used for screening, diagnosis and typing. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in diagnosis of T/NK-cell neoplasms were calculated.

RESULTS

There were 606 males and 422 females in 1028cases, with a mean age of 47.5 years (range 9-86 years). Specimens used for cytologic diagnosis included 996 FNAs, 2 US-FNAs, 13 EUS-FNAs and 17 effusions. Screening for types of lymphoma of MFCI, 139 (13.52 %) cases were T/NK cell lymphoma, 3 (0.29 %) cases were B cell lymphoma T-NHL and B-NHL coexist. A total of 146 suspected T/NK-cell neoplasms were screened out (sensitivity = 94.64 %, specificity = 95.63 % PPV = 72.60 %, NPV = 99.32 %) by MFCI, with 112 (76.71 %) histologically confirmed cases and 6 (4.11 %) false-negative cases identified (3 cases diagnosed as B-cell neoplasms and 1 case as T-cell neoplasm with B-cell neoplasm, which also were confirmed by gene rearrangement. 2 cases were suspicious T-cell-immunophenotypic abnormalities). When used at the diagnostic level, a total of 88 T/NK-cell neoplasms were identified (sensitivity = 68.75 %, specificity = 98.80 %, PPV = 87.50 %, NPV = 96.28 %) with 11 false-positive cases recognized, 9 of which showed typical immunophenotypic T-cell neoplasms features, and 2 exhibited aberrant T immunophenotype.

CONCLUSIONS

MFCI has high sensitivity and specificity in the screening and diagnosis of T/NK-cell neoplasms and may be useful as an alternative diagnosis method in cytology specimens.

Developments in the immunophenotypic analysis of haematological malignancies

Immunophenotyping is the method by which antibodies are used to detect cellular antigens in clinical samples. Although the major role is in the diagnosis and classification of haematological malignancies, applications have expanded over the past decade. Immunophenotyping is now used extensively for disease staging and monitoring, to detect surrogate markers of genetic aberrations, to identify potential immuno-therapeutic targets and to aid prognostic prediction. This expansion in applications has resulted from developments in antibodies, methodology, automation and data handling. In this review we describe recent advances in both the technology and applications for the analysis of haematological malignancies. We highlight the importance of the expanding repertoire of testing capability for diagnostic, prognostic and therapeutic applications. The impact and significance of immunophenotyping in the assessment of haematological neoplasms are evident.

Immunophenotyping of chronic B-cell neoplasms: flow cytometry versus immunohistochemistry

Morphological differentiation between benign and malignant lymphoproliferative disorders (LPDs) can be challenging. Immunophenotyping (IPT) by either technique, flow cytometry or immunohistochemistry (IHC), is an important step in solving such difficulty. Thirty-five newly diagnosed patients with chronic B-cell neoplasms (11 chronic lymphocytic leukemia, 22 non Hodgkin lymphoma and 2 hairy cell leukemia) were included in this study with age range from 20 to 70 years. Monoclonal antibodies surface expression using lymphoproliferative disorders panel (CD45, CD19, CD5, CD10, CD11c, CD20, CD22, CD23, CD38, CD79b, FMC7, CD103, CD25, kappa and lambda light chains) by flow cytometry was done on bone marrow samples. CD20, CD5, CD23, Bcl-2, Bcl-6, kappa and lambda light chain immunostaining were performed on fixed bone marrow trephine biopsy specimen. The sensitivity of IHC was 81.8% in chronic lymphocytic leukemia (CLL) and 100% in non Hodgkin lymphoma (NHL) as regards CD20, 100% in both groups as regards CD5, 46% in CLL and 66.7% in NHL as regards CD23, 33.3% in CLL and 50% in NHL as regards kappa chain, 20% in CLL and 33.3% in NHL as regards lambda chain. We found that IHC and flow cytometry are equally effective in diagnosing CLL; however, IHC might be slightly more sensitive than flow cytometry in detecting bone marrow infiltration in NHL and hairy cell leukemia (HCL).

Polychromatic flow cytometry in the clinical laboratory

Technological advances in flow cytometry include increasingly sophisticated instruments and an expanding range of fluorochromes. These advances are making it possible to detect an increasing number of markers on a single cell. The term polychromatic flow cytometry applies to such systems that detect five or more markers simultaneously. This review provides an overview of the current and future impact of polychromatic flow cytometry in the clinical laboratory. The use of multiple markers has several advantages in the diagnosis and monitoring of haematological malignancies. Cell populations can be analysed more comprehensively and efficiently, and abnormal populations can be distinguished more readily when normal counterparts are present. Polychromatic flow cytometry is particularly useful in the evaluation of plasma cells, and the role of flow cytometry in the assessment of plasma cell disorders is reviewed in depth. There is improved sensitivity in the assessment of small populations, which is critical in the evaluation of minimal residual disease. Flow cytometry can also play a role in assessment of circulating tumour cells in carcinoma. Introduction of polychromatic flow cytometry is a complex process with many challenges including design of antibody panels and instrument compensation. Developments in data analysis are required to realise the full benefits of the other technical advances. Standardisation of protocols may reduce inter-laboratory variation. While the complexity of polychromatic flow cytometry creates challenges, it has substantial potential to improve clinical analysis.

Molecular genetic analysis of haematological malignancies II: mature lymphoid neoplasms

Molecular genetic techniques have become an integral part of the diagnostic assessment for many lymphomas and other chronic lymphoid neoplasms. The demonstration of a clonal immunoglobulin or T cell receptor gene rearrangement offers a useful diagnostic tool in cases where the diagnosis is equivocal. Molecular genetic detection of other genomic rearrangements may not only assist with the diagnosis but can also provide important prognostic information. Many of these rearrangements can act as molecular markers for the detection of low levels of residual disease. In this review, we discuss the applications of molecular genetic analysis to the chronic lymphoid malignancies. The review concentrates on those disorders for which molecular genetic analysis can offer diagnostic and/or prognostic information.