A complete blood count (CBC) is a common blood test that provides valuable information about the kinds and numbers of cells in the blood, including red blood cells, white blood cells and platelets. Doctors frequently order CBC tests as part of regular health screenings or to help diagnose a variety of conditions. But can a CBC blood test also detect lymphoma?
Lymphoma is a type of blood cancer that originates in the lymphatic system. It occurs when lymphocytes, a type of white blood cell, grow abnormally and accumulate in the lymph nodes or other tissues. There are two main categories of lymphoma – Hodgkin lymphoma and non-Hodgkin lymphoma.
While a CBC blood test alone cannot definitively diagnose lymphoma, it can sometimes provide clues that cancer may be present. Certain patterns in the CBC results may prompt a doctor to order additional testing to investigate further.
CBC Test Overview
A complete blood count test measures the following components in a blood sample:
- Red blood cells – The number, size, shape and hemoglobin levels of red cells.
- White blood cells – The total number and types of white cells, including lymphocytes, monocytes, neutrophils, eosinophils and basophils.
- Platelets – The number and size of platelets, disk-shaped cells that help blood clot.
The CBC provides important information about the cells circulating in the blood. Doctors can use it to screen for anemia, infection, inflammatory conditions and other disorders.
Normal CBC Ranges
Reference ranges for CBC results in adults:
| Test | Normal Range |
|---|---|
| Red blood cells | 4.5-6 million cells/microliter |
| Hemoglobin | 13.5-17.5 g/dL (male), 12-15.5 g/dL (female) |
| Hematocrit | 40-54% (male), 36-48% (female) |
| MCV | 80-100 fL |
| White blood cells | 4,500-11,000 cells/microliter |
| Neutrophils | 1,800-7,700 cells/microliter |
| Lymphocytes | 1,000-4,800 cells/microliter |
| Monocytes | 200-1,000 cells/microliter |
| Eosinophils | 15-500 cells/microliter |
| Basophils | 0-200 cells/microliter |
| Platelets | 150,000-400,000 cells/microliter |
These ranges may vary slightly between laboratories. Abnormal results outside of the expected ranges may indicate an underlying problem.
CBC Test Abnormalities Associated with Lymphoma
While some common types of cancer can produce distinctive cell changes on a CBC blood test, the abnormalities seen with lymphoma tend to be more general. However, certain patterns may raise suspicion for lymphoma:
Lymphocytosis
Lymphocytosis refers to an increased level of lymphocytes, a type of white blood cell involved in immune response. In lymphoma, cancerous lymphocytes proliferate uncontrollably, raising the lymphocyte count.
– The normal range for lymphocytes is 1,000-4,800 cells/microliter.
– Lymphocyte levels above 4,000 cells/microliter are considered lymphocytosis.
– In lymphoma, lymphocyte counts may reach tens of thousands of cells/microliter.
However, mildly elevated lymphocyte counts can also occur due to other benign conditions like infection, inflammation or stress. Significant lymphocytosis is more suggestive of a lymphoma diagnosis.
Abnormal Lymphocyte Morphology
In some lymphoma cases, examination of the blood sample under a microscope reveals abnormal structure or appearance of the lymphocytes themselves. The cells may be larger than normal, unusually shaped or immature looking.
Cytopenias
Cytopenias refer to low numbers of one or more types of blood cells. In lymphoma, replacement of normal bone marrow with cancerous cells can lead to deficient production of blood cells.
– Anemia – Low red blood cells or hemoglobin
– Leukopenia – Low white blood cells
– Thrombocytopenia – Low platelets
Elevated Erythrocyte Sedimentation Rate (ESR)
The erythrocyte sedimentation rate is a non-specific marker of inflammation. It reflects how quickly red blood cells settle when a blood sample is allowed to sit.
– Normal ESR is <30 mm/hr in men and <20 mm/hr in women. - Lymphoma may raise ESR levels due to inflammation and abnormal protein levels. - Elevated ESR alone does not confirm a lymphoma diagnosis.
Abnormal Blood Chemistry Findings
While not part of the CBC, other blood chemistry tests are often checked along with it. Findings like:
– High lactate dehydrogenase (LDH)
– High uric acid
– Low albumin
– High globulins
May support suspicion of lymphoma. However, these are general, nonspecific abnormalities.
Limitations of Detecting Lymphoma with CBC
Despite sometimes showing irregular results, a CBC blood test alone cannot definitively diagnose lymphoma for several reasons:
Lack of Specificity
The cell count changes and other findings associated with lymphoma are not unique to that condition. Many other diseases, like infection and autoimmune disorders, can produce similar CBC abnormalities.
Normal CBC in Early Stages
In early stage lymphoma, the CBC may still fall within normal ranges if there has not yet been extensive infiltration and disruption of the bone marrow. Detectable abnormalities tend to correlate with more advanced disease.
Inability to Identify Lymphoma Subtype
There are over 60 subtypes of lymphoma with different characteristics. A CBC cannot provide information to distinguish between different subtypes. Additional diagnostic testing is required for accurate classification.
Does Not Assess Lymph Nodes or Other Tissues
Since lymphoma originates in the lymphatic system, examining involved lymph nodes and organs through scans or biopsies is necessary for diagnosis. CBC assesses circulating blood only.
For these reasons, an abnormal CBC is considered a clue that lymphoma may be present, rather than a definitive test.
Next Steps If Lymphoma is Suspected from CBC
When lymphoma is included on the differential diagnosis based on CBC results, doctors typically pursue the following additional evaluations:
Peripheral Blood Smear
A blood smear allows microscopic examination of blood cell morphology. Lymphoma cells may have distinctive appearances. Flow cytometry can also be performed on blood to assess cells’ surface proteins.
Imaging Tests
CT, PET or MRI scans of the chest, abdomen, pelvis or other areas can reveal swollen lymph nodes or organ involvement. Lymph node biopsy will usually follow.
Lymph Node Biopsy
Examination of lymph node tissue under the microscope is necessary for definitive lymphoma diagnosis and subtyping. Immunohistochemical stains and other special tests are performed.
Bone Marrow Biopsy
Lymphoma often spreads to the bone marrow. Examining a bone marrow sample provides additional information to develop an accurate diagnosis and stage.
So in summary, a CBC blood test may provide hints that lymphoma is present through abnormal cell counts, morphology or associated findings. However, doctors must pursue further testing like scans, lymph node biopsy and bone marrow evaluation to confirm a lymphoma diagnosis and guide appropriate treatment. While not diagnostic on its own, the CBC remains a useful initial screening test that can identify the need for additional procedures when lymphoma is suspected.
Conclusion
A CBC (complete blood count) is a commonly performed blood test that provides an overview of the number and appearance of cells circulating in the bloodstream. In some cases, CBC results can raise suspicion that lymphoma may be present.
Key findings associated with lymphoma include:
– Lymphocytosis – High lymphocyte count
– Abnormal lymphocyte morphology
– Cytopenias – Low levels of red cells, white cells or platelets
– High erythrocyte sedimentation rate
– Abnormal LDH, uric acid, albumin or globulin
However, the CBC has significant limitations in directly diagnosing lymphoma. Non-specific findings, normal results in early disease, inability to classify lymphoma type, and lack of tissue analysis mean a CBC alone cannot definitively diagnose or exclude lymphoma.
When lymphoma is suspected from CBC results, doctors pursue additional testing like blood smear examination, imaging scans, lymph node biopsy, and bone marrow biopsy. Examination of involved nodes and organs is necessary for accurate lymphoma diagnosis and subtyping.
In summary, while the CBC cannot conclusively diagnose lymphoma, it can provide an early clue leading to further investigation when results are suggestive of a lymphoproliferative disorder. It remains a useful initial screening test that warrants follow up when concerning findings are present. However, tissue biopsies are ultimately required to confirm a lymphoma diagnosis.