Lymphoma is a cancer originating in the lymphatic system, part of the body’s immune system, primarily affecting lymphocytes (a type of white blood cell). When symptoms suggest lymphoma, blood tests are often among the first investigations. However, they typically serve as indicators rather than providing a definitive diagnosis.
How Blood Tests Provide Clues
Blood tests are important for initial health assessment when lymphoma is suspected. They reveal general abnormalities prompting further investigation, such as inflammation or infection, which sometimes mimic lymphoma symptoms.
Blood tests also provide insights into body system functioning, like bone marrow’s ability to produce blood cells. Abnormalities in blood cell types can suggest an underlying problem. These changes are not exclusive to lymphoma and can be caused by many other medical conditions. Thus, blood tests function as screening tools, offering initial hints for more specific diagnostic procedures.
Common Blood Markers Associated With Lymphoma
Several blood tests are employed when lymphoma is suspected or to monitor diagnosed individuals:
- Complete Blood Count (CBC): Measures blood components (white blood cells, red blood cells, platelets). In lymphoma, a CBC might reveal elevated or low white blood cell counts if the bone marrow is affected. Anemia (low red blood cell count) and low platelet count can also be observed.
- Lactate Dehydrogenase (LDH): An enzyme found in many tissues; its blood levels increase when cells are damaged or rapidly dividing. Elevated LDH indicates tissue damage or high cellular turnover, common in aggressive lymphomas.
- Inflammatory Markers (ESR, CRP): Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) measure general inflammation. While not specific to lymphoma, elevated levels can suggest an underlying inflammatory process or malignancy.
- Blood Protein Tests: Such as serum protein electrophoresis, examine blood protein types and amounts. Abnormal proteins can be detected in some lymphomas, particularly those involving plasma cells.
- Flow Cytometry: On blood samples, identifies and counts specific cell types based on surface markers. While more commonly used on tissue biopsies or bone marrow, it can sometimes detect abnormal lymphocyte populations in the blood, though this is not sufficient for a definitive diagnosis.
Why Blood Tests Are Not Definitive
Despite valuable clues, blood tests alone cannot definitively diagnose lymphoma. Many conditions can cause similar changes in blood cell counts or marker levels, including infections, other cancers, autoimmune diseases, and certain medications.
Lymphoma is characterized by uncontrolled growth of abnormal lymphocytes, which accumulate in lymph nodes or other lymphatic tissues. Identifying these cancerous cells requires direct examination of affected tissue. Blood tests indicate a potential issue but do not reveal the architectural distortion or cellular characteristics defining lymphoma. While blood test results may raise suspicion, they cannot confirm lymphoma cells in their primary sites or distinguish them from other conditions with similar systemic effects.
The Path to a Lymphoma Diagnosis
When blood tests or other symptoms suggest lymphoma, a comprehensive diagnostic process begins. This starts with a physical examination, where a doctor checks for swollen lymph nodes (neck, armpits, groin) and an enlarged spleen or liver. These findings, combined with blood test results, guide the next steps.
Imaging tests visualize internal structures and identify enlarged lymph nodes or affected organs. Common techniques include computed tomography (CT) scans for detailed cross-sectional images, and positron emission tomography (PET) scans to highlight areas of increased metabolic activity, characteristic of cancer cells. Magnetic resonance imaging (MRI) may also evaluate specific areas like the brain or spinal cord.
Definitive lymphoma diagnosis relies on a biopsy, involving surgical removal of a suspicious lymph node or affected tissue. A pathologist then examines this tissue sample under a microscope to identify cancerous cells, determine their type, and assess other characteristics. A bone marrow biopsy may also be performed to determine if lymphoma has spread to the bone marrow, important for disease staging. This multi-step approach ensures accurate diagnosis and informs treatment decisions.