Follicular lymphoma is a slow-growing non-Hodgkin lymphoma originating from B-lymphocytes, immune cells that grow abnormally and primarily accumulate in lymph nodes. This article details the evaluations and tests involved in its diagnosis.
Recognizing Potential Signs
Initial indicators of follicular lymphoma are often subtle. Many individuals first notice painless swelling in lymph nodes, commonly in the neck, armpit, or groin. These enlarged nodes may fluctuate in size or remain persistently swollen. Some people are diagnosed incidentally during medical evaluations for other conditions, without experiencing symptoms.
Beyond localized swelling, systemic symptoms, known as “B symptoms,” can occur, though less frequently than in more aggressive lymphomas. These include unexplained fevers, drenching night sweats, and significant unexplained weight loss (typically 10% or more of body weight within six months). General fatigue is another common, non-specific symptom. These symptoms are not unique to follicular lymphoma and require thorough medical evaluation.
First Steps in Diagnosis
The diagnostic process begins with a healthcare provider visit. The doctor gathers a detailed medical history, including symptom onset and family history. A thorough physical examination follows, checking for swollen lymph nodes in the neck, armpits, and groin. The examination also includes checking for enlargement of the spleen or liver, as these organs can be involved.
Initial laboratory tests, such as a Complete Blood Count (CBC), are common. A CBC measures red blood cells, white blood cells, and platelets. Abnormal counts might suggest bone marrow involvement or other issues. While these steps guide further investigation, blood tests alone cannot definitively diagnose follicular lymphoma.
Confirming the Diagnosis
The definitive diagnosis of follicular lymphoma relies on a biopsy, where tissue is removed and examined. An excisional biopsy, which involves surgically removing an entire lymph node, is often preferred as it provides sufficient tissue for comprehensive analysis. Alternatively, a core needle biopsy (small sample) or an incisional biopsy (part of a larger affected area) may be performed. A bone marrow biopsy may also determine if lymphoma cells have spread to the bone marrow.
Imaging tests play a significant role in identifying affected areas and assessing disease extent. Computed tomography (CT) scans provide detailed images of lymph nodes and organs. Positron emission tomography (PET) scans are highly sensitive for detecting lymphoma cells and can help differentiate active disease from non-cancerous changes. Magnetic resonance imaging (MRI) may evaluate specific areas, such as bone or central nervous system involvement, though it is less commonly used than CT for initial diagnosis.
Certain blood tests offer additional information, though they are not diagnostic on their own. Elevated Lactate dehydrogenase (LDH) levels can indicate a higher tumor burden or aggressive disease transformation. Beta-2 microglobulin levels may suggest increased disease activity. These tests complement biopsy and imaging findings.
What Happens After Confirmation
Once a biopsy confirms lymphoma cells, a specialized pathologist reviews the sample. The pathologist confirms the specific type of lymphoma and determines its grade (typically 1 to 3). This analysis involves techniques like immunohistochemistry and flow cytometry, which identify specific protein markers on the lymphoma cells. These markers help differentiate follicular lymphoma from other conditions.
Genetic testing, particularly Fluorescence In Situ Hybridization (FISH), is also performed. This test looks for specific chromosomal rearrangements, notably the translocation t(14;18). This translocation, present in 70% to 95% of cases, involves the immunoglobulin heavy chain gene (IGH) and the BCL2 gene. Its presence leads to BCL2 protein overexpression, which hinders cell death and contributes to lymphoma cell accumulation.
Following diagnosis confirmation, staging determines how widespread the lymphoma is. The Ann Arbor staging system is widely used, often with modifications. Staging integrates findings from imaging tests and bone marrow biopsy results. Stages range from I to IV, indicating the number and location of involved lymph nodes and spread to organs outside the lymphatic system. Accurate staging is fundamental for prognosis and guiding treatment strategies.