You might have a number of tests to investigate your symptoms and confirm a diagnosis of lymphoma, including: 

• medical history and physical examination 
• blood tests for blood cell counts and other laboratory tests (blood tests may not be able to diagnose lymphoma, but they can check if your bone marrow, kidneys and liver are working – if they are not working properly, it could be a sign that lymphoma is present^[16])  
• removal of a small piece of tissue (biopsy) from the lymph nodes, skin or bone marrow^[17] to be examined under a microscope 
• imaging tests, such as X-ray of the chest, computerised tomography (CT) scan, magnetic resonance imaging (MRI) scan, positron emission tomography (PET) scan or ultrasound – these tests may include getting a dye injected into a vein to help the imaging detect possible cancers 
• removal of fluid from the spinal cord using a needle (known as a lumbar puncture or spinal tap) – this test is not common, but it may be used to see if the lymphoma has spread to the central nervous system, or to deliver chemotherapy^[18]. 

Staging

If you are diagnosed with lymphoma, you might have more tests to determine the stage of the disease and whether the cancer has spread to other parts of the body. These tests may include imaging tests, blood tests, biopsies or tests of heart and lung function. Knowing the stage of the disease helps your medical team plan the best treatment for you.  

In most cases, lymphoma (both Hodgkin and non-Hodgkin) is divided into 4 stages, depending on how far the cancer has spread: 

• Stage I – 
  • lymphoma is in only 1 lymph node area (it may be in more than one lymph node within the same area); OR 
  • lymphoma is in only 1 organ in the lymphatic system (lymphoid organ) such as the thymus; OR 
  • lymphoma is in only 1 part of a single organ outside the lymphatic system. 
• Stage II – 
  • lymphoma is in 2 or more lymph node areas on the same side of the diaphragm (either above or below); OR 
  • lymphoma is in 1 lymph node area and extends into a nearby organ. 
• Stage III – 
  • lymphoma is in at least 1 lymph node area above and at least 1 lymph node areas below the diaphragm; OR 
  • lymphoma is in lymph node areas both above and below the diaphragm, and has spread to the spleen or a nearby organ, or both.  
• Stage IV – 
  • lymphoma has spread widely through 1 or more organs outside the lymphatic system, and may be in nearby lymph nodes; OR 
  • lymphoma is in 2 organs in distant parts of the body (and not in nearby lymph nodes); OR 
  • lymphoma is in the liver, bone marrow, lungs or cerebrospinal fluid. 

Sometimes other descriptions are added to these stages to describe specific characteristics of the disease. 

Non-Hodgkin lymphoma is also categorised by grade: 

• Lowgrade (also called indolent lymphoma) refers to slowgrowing lymphoma.^[19] 
• Intermediategrade and highgrade (also called aggressive lymphoma) refers to fastgrowing lymphoma, which needs to be treated as soon as possible for the best chance of destroying the cancer.^[20] 

Lymphoma of the skin, is categorised by: 

• how much of the skin surface is affected 
• how far the lymphoma has spread to the lymph nodes and other organs  
• the number of lymphoma cells in the blood (this is not always used). 

A different staging system is also used for non-Hodgkin lymphoma in children.