Diagnosis of Non-Hodgkin’s Lymphoma

Summary

Diagnosis of Non-Hodgkin’s Lymphoma (NHL) is usually done using traditional methods such as clinical laboratory testing, lymph node biopsy, bone marrow aspiration, immunophenotyping and imaging methods. However, in recent times molecular methods such as polymerase chain reaction, microarrays, and fluorescent in situ hybridization methods are more efficient in monitoring and treatment outcomes.

Introduction

Non-Hodgkin’s lymphoma (NHL) is a haematological malignancy with a variety of clinical and molecular features that doctors also use to help diagnose it. Traditional methods used such as lymph node biopsy with fine-needle aspiration or bone marrow aspiration using cytogenetics and immunophenotyping to identify malignant cells if any.

Traditional Methods

Clinical laboratory testing

Clinical laboratory tests in the diagnosis of NHL includes tests performed in haematology, chemistry, and also biochemistry. However, it is not limited. Complete blood count (CBC) often reports various blood parameters within normal limits at the onset of the disease and as the disease progresses, CBC may also denote anaemia symptoms that are secondary to bone marrow infiltration, leukopenia, thrombocytopenia, or pancytopenia^​1​.

Lymph node biopsy/fine-needle aspiration

Fine needle aspiration (FNA) cytology besides being rapid, accurate and economical; is reliable, and minimally invasive procedure widely used to assess the initial detection of tumours in different organs such as the salivary glands, thyroid, lymph, and breast. However, aspiration of lymph nodes with a fine needle is a successful diagnostic method for lymphadenopathy. Furthermore, Resection biopsy and histopathological examination remain the gold standard for primary diagnosis and classification of NHL. Besides this, one can use fine needle aspiration to distinguish between reactive and neoplastic lymphoid cells, which can help in lymphoma classification^​2​.

Bone marrow aspiration

Bone marrow aspiration is performed primarily for cytological evaluation. However, it is also performed for other specialised studies such as immunophenotypic, molecular genetics, cytogenetic^​3​. A trephine biopsy performed with the same procedure can diagnose NHL, especially low-grade lymphoma, which often infiltrates the bone marrow.

Immunophenotyping

Besides Flow cytometric (FC) Immunophenotyping analysis, cytogenetic analysis is yet another method which is important methods for diagnosing and classifying many haematological disorders^​4​. But in recent years, flow cytometry has also been shown to be useful in assessing lymphoproliferative disorders, primarily lymph nodes from surgical specimens or fine needle cytometry. However, several reports have highlighted the high sensitivity of NHL detection by combining flow cytometry and fine-needle cytology^​5​.

Imaging

One of the most difficult aspects of lymphoma imaging is the evaluation of response to treatment. However, the distinction between tumour and fibrosis in radiographs poses problems in the interpretation of Hodgkin’s lymphoma and non-Hodgkin’s lymphoma. Besides, Positron emission tomography (PET) scanning has become an advanced diagnostic method to detect and monitor the response to treatment in NHL^​6​.

Molecular Methods

The primary goal of molecular diagnosis of lymphoma is to detect translocation, genetic abnormalities, or clonality which can be achieved essentially, using flow cytometry, immunocytochemistry, and polymerase chain reaction (PCR).

Polymerase chain reaction (PCR)

PCR is the most commonly used method of molecular diagnosis^​7​ and can also be used to identify monoclonal rearrangements of T cell receptors or IgH genes and translocations associated with the BCL-1 and BCL-2 genes.

Fluorescent in situ hybridization (FISH)

Fluorescent in situ hybridization is based on the principle that complex karyotype changes characterize multiple lymphomas^​8​. However, specific FISH probes are useful for identifying traits or marker chromosomes. Moreover, FISH offers significant advantages over conventional cytogenetics in chromosome translocation, deletion, and gene amplification studies^​7​.

DNA microarrays

Gene expression profiling can be performed using DNA microarrays which holds great promise for the future of molecular diagnostics. Moreover, a gene expression database can be created by analyzing and comparing hundreds of tumour samples, and specific expression patterns can be linked to prognosis and treatment outcomes.

References