Diagnosis

NHL can be diagnosed from a sample of bone marrow or lymph node, or from any other part of the body which is affected. Doctors will often also perform a computed tomography (CT) scan of the head, chest, abdomen and pelvis, although a brain scan will not necessarily tell the difference between NHL and other brain problems such as toxoplasmosis. A sample of the cerebrospinal fluid (CSF) may be taken by lumbar puncture to check for malignant lymphoma cells. The presence of EBV in the CSF increases the likelihood that a brain mass is lymphoma. If there are gastro-intestinal symptoms, the gut may be examined used a fibre-optic endoscope. Some blood tests can also be useful. These look for unusually high levels of lactase dehydrogenase (LDH) or uric acid.

If lymphoma is found, it is graded as low, intermediate or high grade, based on how rapidly the cancerous cells are growing. It is also staged (stages I to IV) based on the extent of tissue involvement, as assessed by body scans and CSF tests. A further classification takes account of the shape and size of the B-cells that make up the lymphoma.

An experimental assay using free light chains - a measure of B-lymphocyte antibody production, elevated in cases of lymphoma - has been found to predict the risk of devloping NHL in people living with HIV.¹