23rd July 2024

Overview of lymphoma

Lymphomas are a heterogenous group of malignancies resulting from clonal proliferation of lymphocytes in lymphoid tissue. They are the most common haematological malignancy.

Lymphomas are subdivided into two broad groups:

1. Hodgkin lymphoma (HL): around 10% of lymphomas are characterised by the presence of Reed-Sternberg cells on blood film. This is a B-cell lymphoma.
2. Non-Hodgkin lymphoma (NHL): around 90% of lymphomas, no Reed-Sternberg cells on blood film. Around 85% originate from B-cells and 15% from T-cells/NK cells.

Diagnosis and staging of lymphoma

There are three main aspects to definitive diagnosis of HL and NHL:

1. Tissue biopsy: excisional biopsy of a peripheral lymph node (LN). Fine needle aspiration does not provide sufficient material for a histological diagnosis and classification.
2. Imaging: chest X-ray, CT of neck, chest, abdomen and pelvis with contrast and FDG-PET scan. Used to stage disease and guide tissue biopsy.
3. Immunohistochemistry

Staging of HL and NHL is via the Lugano classification, a modification of the classic Ann Arbor staging system. This takes into account the number and site of LNs and/or extra-lymphatic organs affected, as well as the presence or absence of ‘B’ symptoms, defined as:

• Unexplained fever >38°C in the last month
• Recurrent drenching night sweats in the last month
• Weight loss >10% within six months of diagnosis

A sub-classification of ‘A’ denotes the absence of ‘B’ symptoms, whereas ‘B’ denotes their presence, e.g. IIA or IIIB.