Three days before a woman arrived at a Brooklyn hospital with a firm, tender mass limiting the movement of her right arm, a radiologist had read her mammogram and assigned it BI-RADS 3: probably benign. The biopsy that followed found diffuse large B-cell lymphoma.
That case, published in Cureus, came with a detail that changes how it should be read. The patient had AIDS, and immunosuppression is a recognized driver of aggressive extranodal lymphoma. Her pre-test probability was never that of an average screening patient. What the case still demonstrates is a specific and under-appreciated problem: a small group of breast cancers that are not carcinomas at all, that imaging cannot reliably distinguish from anything else, and that require the opposite treatment from the one a breast surgeon would normally reach for.
A case report published this month in Frontiers in Oncology makes the same point from the other direction. A 39-year-old woman presented with two palpable right breast masses, graded BI-RADS 4A. Prominent vascularity and intermediate-to-hard stiffness on elastography raised suspicion of malignancy. What the imaging could not do, the authors write, was reliably tell primary breast lymphoma from primary breast carcinoma. She underwent surgical excision, and the pathology came back as lymphoma.
The Gap Between a Reassuring Read and a Wrong One
BI-RADS is the standardized scale radiologists use to communicate how suspicious a breast finding looks, running from 0 to 6. Category 3, probably benign, is not a dismissal. It is defined as having a malignancy risk of 2 percent or less, and it includes a specific instruction: repeat imaging in six months, based on the reasoning that a cancerous mass changes over time, whereas a benign one usually does not.
That system works well because it is calibrated to the overwhelming majority of breast lesions, which are either ordinary benign changes or carcinomas that announce themselves with irregular shapes, infiltrative margins, and marked stiffness. It is not calibrated to a tumor that grows without producing any of those features.
A Category That Is Both Rare and Treated Completely Differently
Primary breast lymphoma accounts for less than 1 percent of non-Hodgkin lymphomas and roughly 0.5 percent of breast malignancies. A 2026 review in Radiology Case Reports puts B-cell lymphomas at over 90 percent of cases, with diffuse large B-cell lymphoma accounting for more than half.
Burkitt lymphoma of the breast sits at the rarest end of that already rare category. It is among the fastest-proliferating human tumors known. StatPearls lists the breast among the sites Burkitt lymphoma only rarely reaches, alongside the thyroid, skin, and testes.
The imaging features that push radiologists toward reassurance are often the ones lymphoma has. Because these tumors do not provoke the dense fibrous reaction that carcinomas do, they tend to produce lobulated masses with indistinct margins and intermediate stiffness rather than the spiculated, rigid lesions clinicians are trained to fear.
Why the Surgery Question Matters So Much Here
For most breast malignancies, surgery is central. For primary breast lymphoma, it is not, and this is where a misread scan can cost a patient something irreversible.
Research has not shown that mastectomy improves survival or recurrence rates in primary breast lymphoma, a point made in teaching material from UCLA Health and repeated across the case literature. The disease is treated systemically. R-CHOP chemoimmunotherapy is standard for the diffuse large B-cell form. Burkitt lymphoma is treated with intensive regimens such as CODOX-M/IVAC, along with aggressive management of tumor lysis.
In a Ugandan case, a 16-year-old girl with primary breast Burkitt lymphoma had already been advised toward surgery at a peripheral health center. Her team performed a touch imprint specifically to reach a diagnosis fast enough to avoid it. The tumor shrank to roughly half its size after one cycle of chemotherapy, and at the time of publication, she was still on treatment and doing well.
Outcomes for Burkitt lymphoma are often good when it is caught and treated correctly. A review in the New England Journal of Medicine notes that most patients are cured with chemotherapy and prevention of tumor lysis, with relapse and central nervous system involvement carrying a poor prognosis.
What Should Actually Prompt a Biopsy
None of this means that a reassuring mammogram should be distrusted. The 2 percent ceiling on BI-RADS 3 is why the standard response is a repeat scan in six months rather than a needle.
The signal that matters in these cases is not the imaging category. It is the discrepancy between the imaging and everything else. A mass that is growing quickly, that is large, that is changing the shape or skin of the breast, or that is accompanied by fever, night sweats or weight loss does not fit a probably-benign reading, and the mismatch itself is the finding.
Rapid growth is the recurring thread through the published lymphoma cases. So is the resolution: in each of them, the answer came from tissue, not from a scan.
Anyone with a new or enlarging breast lump should have it evaluated regardless of when their last mammogram was and regardless of what it showed. Anyone told a lesion is probably benign but who watches it grow should say so, because the interval change is clinically meaningful information. These are conversations for a clinician, not decisions to make from case reports about a cancer most physicians will never see.
Key Questions Answered
What is primary breast lymphoma?
A lymphoma that begins in breast tissue rather than spreading there from elsewhere. It makes up less than 1 percent of non-Hodgkin lymphomas and about 0.5 percent of breast malignancies.
Why can imaging miss it?
Because lymphoma often produces smoother, less rigid masses without the spiculated margins that flag carcinoma. Those features can read as reassuring.
Does this mean probably-benign results cannot be trusted?
No. BI-RADS 3 is defined as carrying a malignancy risk of 2 percent or less. The concern is a mismatch between a reassuring scan and a large or rapidly growing mass.
Why does the distinction change treatment?
Primary breast lymphoma is treated with chemotherapy. Published research has not shown that mastectomy improves survival or recurrence in this disease.
How rare is Burkitt lymphoma of the breast?
Extremely. It is among the rarest presentations of an already rare category, and the published literature consists largely of individual case reports.
What should someone do about a growing lump?
Have it evaluated promptly, and mention any change since a previous scan. Interval growth is meaningful information for the clinician deciding whether to biopsy.
