Understanding a DLBCL report: pathology, FISH, IPI and PET findings

A DLBCL report can contain several different languages at once: a diagnostic name, positive stains, gene results, percentages, a stage and a PET score. These do not all measure severity. Pathology identifies the lymphoma, selected laboratory methods refine its classification, imaging maps disease and response, and clinical scores summarize risk. Reading each result according to its purpose is more useful than treating the largest number as the most important finding. [S1,S3]

Key takeaways

These excerpts come from the original article. Read the full sections below for context.

Diffuse large B-cell lymphoma, not otherwise specified is a defined diagnostic category. Wording such as suspicious for, favors or pending further testing indicates that the conclusion is not yet complete. A report may instead describe transformation from an indolent lymphoma, primary mediastinal large B-cell lymphoma or a particular high-grade B-cell entity. These distinctions should not disappear when the diagnosis is shortened in a referral letter. [S2]
Stage describes where the lymphoma is distributed. Stage IV DLBCL can still be treated with curative intent, so statements about stage IV in other cancers should not be transferred directly to lymphoma. The clinician also considers the affected organs, mass size, symptoms and functional status. These details can change how urgently treatment must begin and what support is needed. [S1]
A concise summary can list the complete diagnosis, date, rearrangement results, baseline stage and IPI, main disease sites, treatment regimen and most recent response. Mark unresolved items as pending or requiring review rather than deleting them to make the summary appear tidy. The original reports must remain available behind this page because another clinician may need detail not included in the summary.

Quick answer

Full guide

Keep the full report, including comments and supplementary pages. A screenshot containing only the words high grade or increased uptake can omit the limitations that explain them. This guide is for preparing a clinical discussion. Severe breathlessness, bleeding, confusion or rapidly worsening pain calls for medical assessment before further report interpretation.

Start with the complete diagnostic line

Diffuse large B-cell lymphoma, not otherwise specified is a defined diagnostic category. Wording such as suspicious for, favors or pending further testing indicates that the conclusion is not yet complete. A report may instead describe transformation from an indolent lymphoma, primary mediastinal large B-cell lymphoma or a particular high-grade B-cell entity. These distinctions should not disappear when the diagnosis is shortened in a referral letter. [S2]

Check the specimen site, date and sampling method. An excised node, a core biopsy and a fine-needle aspirate do not provide identical material. Ask whether the sample was obtained before treatment. If a pathology review changes the name, the doctor should explain what new evidence led to the change and whether the regimen needs reconsideration. An unusual lesion at another site may occasionally require separate sampling.

Interpret CD20 in the context of the tissue

CD20 is a B-cell-associated marker and is relevant to therapies such as rituximab. Positivity alone does not establish DLBCL, because normal B cells can also express it. The pathologist considers which cells stain, their appearance and the accompanying markers. A negative stain often helps exclude another diagnosis rather than simply removing a treatment option. [S3]

For a relapse biopsy, the team may need to confirm the current diagnosis and relevant antigen expression after previous targeted treatment. Preserve the method and full wording, not just a handwritten CD20-positive label. If a result seems different from an earlier report, ask whether this reflects a true biological change, sample differences or interpretation. The distinction can matter when selecting an antibody or cell-based treatment.

Do not treat cell of origin as a ready-made prescription

GCB, non-GCB and ABC refer to aspects of cell-of-origin classification. An immunohistochemical algorithm is not identical to gene-expression profiling, and the labels are not always interchangeable. A non-GCB result does not mean cure is impossible. It also does not, by itself, justify adding a drug advertised for a molecular subgroup. [S3]

Ask which method was used and whether the result changes this treatment decision. Sometimes it mainly refines biological understanding or provides a reason to discuss a study. That is still useful information, but it should be described accurately. The patient should know whether a test selects an established treatment, informs risk or investigates an unresolved question.

Separate double expression from rearrangements

MYC and BCL2 immunohistochemistry measures protein expression. FISH can identify gene rearrangements. Double expression therefore does not establish a rearrangement-defined double-hit lymphoma, and a high proliferation index cannot substitute for the genetic test. Ask whether FISH was performed, is pending or could not be completed because there was insufficient tissue. Those are three different situations. [S2,S3]

Terminology has also evolved. Older material may group MYC/BCL6 and MYC/BCL2 rearrangements differently from newer classifications. Keep the individual gene conclusions and let a hematopathologist explain the current diagnostic wording. A shorthand term from an online group should not override the actual laboratory result. If uncertainty could change the regimen, ask how the team will resolve it without unnecessary delay.

Put Ki-67 in proportion

Ki-67 estimates the proportion of cells showing a proliferation-associated signal. DLBCL is an aggressive lymphoma, so a high percentage is not unexpected. That value is interpreted with morphology, genetics and the clinical presentation. It does not alone define every high-grade subtype or mandate the most intensive available regimen.

Sampling and interpretation can affect the percentage. Comparing your value with another patient's value is therefore a poor way to estimate an individual outcome. A better question is whether this result materially changes your treatment. If the tissue description and the clinical behavior do not fit, expert review or additional sampling may be more useful than repeated discussion of the percentage. [S3]

Understand lymphoma stage on its own terms

Stage describes where the lymphoma is distributed. Stage IV DLBCL can still be treated with curative intent, so statements about stage IV in other cancers should not be transferred directly to lymphoma. The clinician also considers the affected organs, mass size, symptoms and functional status. These details can change how urgently treatment must begin and what support is needed. [S1]

Bowel involvement, for example, raises different immediate concerns from an uncomplicated bone lesion. Counting the number of spots on a report does not tell the patient how many drugs or cycles are necessary. Ask for the integrated stage and risk assessment, and ask which individual finding influenced the plan. This turns a frightening label into a more specific discussion.

Distinguish LDH from the IPI

LDH is a blood chemistry measurement that can rise with lymphoma activity but also with other tissue injury or illness. Read it alongside the laboratory's upper reference limit and the collection date. A mildly abnormal value is not proof of relapse. Trends may be useful, but they still need symptoms, other tests and sometimes imaging for interpretation.

The International Prognostic Index combines clinical variables such as age, LDH, performance status, stage and extranodal involvement. It describes risk across groups rather than a fixed life expectancy for one person. Some treatment indications also use an IPI threshold. The US polatuzumab-R-CHP approval is one example, but its criteria do not establish a Chinese hospital's prescribing or reimbursement rules. Ask whether the score is being used for risk communication, treatment selection or both. [S4]

Read SUV and Deauville as imaging tools

An SUV describes radiotracer uptake; it is not tumor diameter and does not independently diagnose a lymphoma subtype. Blood glucose, timing and scanner methods can influence measurements. Infection and inflammation can also be active on PET. Comparing isolated decimal values across reports is less reliable than an expert review of the complete images and clinical setting. [S1]

Deauville scoring compares uptake with reference tissues and helps describe metabolic response. Timing matters: an interim scan and an end-of-treatment scan answer different questions. The treatment protocol matters too. A residual mass may remain after metabolic activity has resolved, while uncertain uptake after therapy may require reassessment or biopsy before a major treatment change. Ask what evidence would justify that next step rather than changing treatment after reading a score online. [S3]

Relate blood counts and organ tests to the cycle date

Low neutrophils, platelets or hemoglobin during treatment can have several explanations, including medication effects, infection and the lymphoma itself. The date relative to treatment is essential. A normal result before cycle one does not guarantee safety later, and one low count does not prove marrow progression. Ask when to repeat testing and which findings would alter the next cycle. [S20]

Kidney, liver and cardiac abnormalities may affect doses, fluid plans and drug choices. Keep the individual hepatitis B test results rather than a general statement that the test was fine. Fever of 38°C or above, shaking chills or breathlessness warrants prompt contact even if a new blood count has not yet been obtained. Waiting for an online interpretation should not delay assessment of a possible infection. [S8]

Make a second opinion useful

Arrange records by date in separate pathology, imaging, laboratory and treatment sections. Retain units, reference intervals and test methods. Translation should preserve uncertainty: negative, not tested and insufficient sample must not be converted into the same phrase. Before sending slides, blocks or DICOM files to China, confirm what the receiving department requires. [S2]

Ask the center to quote separately in Chinese yuan for slide review, additional stains or FISH, image review and any new procedure. Turnaround depends on whether new material or external testing is needed. This article has no verified patient-specific price, and a universal review package cannot be assumed to cover every problem. The useful purpose of a second opinion is to resolve a question that affects care. Avoid paying twice for a test whose answer is already reliable and sufficient. [S10]

Keep a one-page interpretation with the originals

A concise summary can list the complete diagnosis, date, rearrangement results, baseline stage and IPI, main disease sites, treatment regimen and most recent response. Mark unresolved items as pending or requiring review rather than deleting them to make the summary appear tidy. The original reports must remain available behind this page because another clinician may need detail not included in the summary.

After treatment, actual doses, major toxicities and the final imaging assessment become part of the follow-up record. [S12] A CAR T-cell center or trial team may need to recheck the diagnosis and every previous treatment line; a referral saying relapsed DLBCL is insufficient for all eligibility decisions. Research-only investigations require an explanation and informed consent. A clear record lets the next team spend the consultation on the current decision instead of rebuilding the history. [S11,S16]