Why Is an Excisional Biopsy Often Needed to Diagnose DLBCL?

If your doctor suspects you have Diffuse Large B-Cell Lymphoma (DLBCL), they will likely recommend an excisional biopsy—a surgical procedure to remove an entire enlarged lymph node. It is natural to wonder why a surgeon needs to remove a whole lymph node when simple needle biopsies are commonly used to diagnose other cancers. The short answer is that diagnosing DLBCL often requires a pathologist to examine the intact “architecture” of the lymph node, which a needle biopsy usually cannot provide ^[1].

However, an excisional biopsy is not universally required for every patient. It is considered the ideal standard when it can be performed safely, but if the lymph node is deep or surgery carries too much risk, your care team may rely on other sampling methods ^[2].

The Limits of Needle Biopsies

A Fine-Needle Aspiration (FNA) uses a thin needle to pull a small sample of fluid and cells from a tumor. While this is less invasive, it only captures a limited scattering of cells and does not preserve the tissue’s natural structure ^[3]. Imagine trying to understand the plot of a movie by looking at three random screenshots; you might see the characters, but you will not know the context of what is happening.

Additionally, if a lymph node contains areas of dead tissue (necrosis), a needle biopsy might accidentally draw from these dead zones ^[4][5]. This can result in a sample that cannot be tested properly. FNA can sometimes help with preliminary screening or a test called flow cytometry (which looks at cells suspended in fluid), but it often cannot establish the full lymphoma classification by itself ^[6].

A Core Needle Biopsy (CNB) uses a slightly larger needle to remove a small cylinder of tissue. A CNB provides more information than an FNA and is commonly used if an excisional surgery is unsafe or the lymph node is difficult to reach ^[2][7]. If a core biopsy does not provide a definitive diagnosis, your doctor may then recommend a repeat biopsy or an excision ^[1].

The Importance of Lymph Node Architecture

To definitively diagnose DLBCL, a pathologist must look at the lymph node’s architecture—the physical arrangement and growth pattern of the cells within the node ^[1].

Many types of large B-cell lymphomas share overlapping features, making them very difficult to tell apart by just looking at individual cells ^[8]. For example, DLBCL must be carefully distinguished from conditions like marginal-zone lymphoma or a fast-growing version of mantle-cell lymphoma ^[9]. Some lymphomas also start as slow-growing diseases and later transform into DLBCL. By examining the whole lymph node, the pathologist can see the physical boundaries of the cells and how they interact with their environment. This big-picture view is essential for an accurate diagnosis ^[10][11].

Getting Enough Tissue for Specialized Tests

Modern medicine relies on advanced molecular and genetic tests to understand exactly how the cancer behaves. While an excisional biopsy does not guarantee a perfect sample, it provides the best chance of gathering enough high-quality tissue for a complete diagnostic workup ^[1][10]:

• Immunohistochemistry (IHC): This test uses special dyes to detect specific proteins in or on the lymphoma cells. IHC helps determine your “cell-of-origin” subtype of DLBCL, such as Germinal-Center B-cell-like (GCB) or Activated B-cell-like (ABC) ^[12][13].
• FISH Testing: Fluorescence In Situ Hybridization (FISH) is a genetic test that looks for specific gene rearrangements in the MYC, BCL2, and BCL6 genes ^[14]. Identifying these rearrangements is critical for identifying specific high-grade lymphomas (sometimes referred to as “double-hit” lymphomas), which can directly influence your classification and treatment decisions ^[15][16].

While it is technically possible to perform FISH testing on a core needle biopsy, having a full lymph node gives the laboratory more tissue to allocate across morphology, flow cytometry, IHC, and genetic testing ^[4][17]. Note that the results for these different tests often arrive in stages over several days to weeks, rather than all at once.

Surgical Risks and Recovery

While an excisional biopsy for a superficial node (like in the neck or armpit) might be done as an outpatient procedure under local anesthesia, nodes located deep in the chest or abdomen require more involved surgery and general anesthesia. The risks—which can include bleeding, infection, pain, scarring, or nerve damage—depend entirely on the lymph node’s location. Your surgeon should explain the specific risks, the type of anesthesia required, and the expected recovery time before you decide on the procedure.