Breast lymphoma is a rare malignant tumor of the breast, divided into primary and secondary (systemic). Primary breast lymphoma constitutes less than 0.5% of all breast malignancies and is most commonly diffuse large B-cell lymphoma (DLBCL) type. Secondary involvement (breast spread in systemic lymphoma) is much more common than primary. On imaging, it generally appears as a well-defined, round/oval, homogeneously hypoechoic (US) or homogeneously dense (mammography) mass — spiculated margins, calcification, and architectural distortion are typically absent. Bilateral involvement is seen in 10-20% of patients and is an important diagnostic clue. Axillary lymphadenopathy may be present. Breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) is a separate clinicopathological entity originating from the implant capsule. Treatment is chemotherapy-focused (not surgical) — therefore accurate diagnosis is critical.
Age Range
50-80
Peak Age
65
Gender
Female predominant
Prevalence
Rare
Primary breast lymphoma originates from mucosa-associated lymphoid tissue (MALT) or perilobular/periductal lymphoid cells within breast tissue. In DLBCL, the most common type, monoclonal proliferation of B-lymphocytes creates a rapidly growing mass. The well-defined appearance on imaging results from lymphoma's expansile (pushing) growth pattern — unlike epithelial carcinomas, it does not create desmoplastic stromal reaction, infiltrative spiculated margins, or architectural distortion. Homogeneous hypoechoic (US) and homogeneous dense (mammography) appearance results from the uniform cellular composition — lymphoma consists largely of the same type of lymphoid cells, necrosis, cystic change, or calcification is rare. Prominent posterior acoustic enhancement on US is related to low ultrasound attenuation of high cellular density — tightly packed small round cells absorb ultrasound waves minimally. Bilateral involvement reflects lymphoma's capacity for hematogenous/lymphatic spread — bilateral involvement is rare in carcinoma. Absence of calcification results from lymphoma lacking mechanisms that produce necrotic or dystrophic calcification (not associated with ductal structures, no secretory calcification).
The most important diagnostic feature of breast lymphoma is that despite being a malignant mass, it does not show the typical triad of epithelial carcinoma (spiculated margins, calcification, architectural distortion). Well-defined, homogeneous, hypoechoic mass — shows 'benign-like morphology' unlike carcinoma. This discordance (malignant behavior + benign morphology) is a pathognomonic clue for lymphoma.
Well-defined, round or oval, homogeneous hypoechoic mass — internal echoes are uniform and low intensity. Prominent posterior acoustic enhancement is seen behind the lesion (cyst-like transmission increase but solid structure). Margins may be smooth or mildly lobulated. Spiculated margins are typically absent. No calcification. Parallel orientation (wider than tall) is expected but some aggressive cases may show non-parallel orientation.
Report Sentence
On US, a ___ x ___ mm well-defined, homogeneous hypoechoic solid mass with prominent posterior acoustic enhancement is seen in the ___ quadrant of the right/left breast; lymphoma should be considered in the differential.
Well-defined or partially defined, round/oval, homogeneously dense mass on mammography. Calcification is typically absent — this is an important negative finding. No architectural distortion or spiculated margins. Halo sign (thin radiolucent rim) may be seen (pushing growth). May be occult in dense breast tissue. If bilateral masses are present, lymphoma is a strong possibility.
Report Sentence
On mammography, a ___ x ___ mm well-defined, homogeneously dense mass is seen in the ___ quadrant of the right/left breast without calcification or architectural distortion; lymphoma should be considered in the differential.
Well-defined mass with homogeneous intermediate-to-hyperintense signal on T2W MRI. Signal intensity is mildly increased compared to normal breast parenchyma. Internal heterogeneity is minimal — necrosis or cystic change is rare. Perilesional edema (halo) may be present. Skin thickening may be seen (especially in inflammatory lymphoma type).
Report Sentence
On T2W MRI, a ___ x ___ mm well-defined, homogeneous intermediate-to-hyperintense solid mass is seen in the ___ quadrant of the right/left breast.
Homogeneous, intense enhancement on contrast-enhanced MRI. Kinetic curve analysis may show Type II (plateau) or Type III (washout) pattern. Homogeneous enhancement reflects uniform vascularity of the lesion — different from heterogeneous enhancement in carcinomas. Significant diffusion restriction and low ADC values (<1.0 x 10^-3 mm²/s) are expected on DWI — high cellular density.
Report Sentence
The mass shows homogeneous intense enhancement on contrast-enhanced MRI with significant diffusion restriction and low ADC values on DWI; findings consistent with lymphoma.
Avid FDG uptake on PET-CT — SUVmax is generally high (>5-10). PET-CT is critically important for assessment of systemic spread — bilateral breast involvement, axillary, mediastinal, retroperitoneal lymphadenopathy, and extranodal involvement areas are assessed in a single session. Mandatory for Ann Arbor staging and treatment planning. Also used for treatment response monitoring.
Report Sentence
The mass in the ___ quadrant of the right/left breast shows avid FDG uptake on PET-CT (SUVmax: ___); axillary/mediastinal lymphadenopathy is present/absent; findings consistent with systemic lymphoma.
Criteria
Most common type (50-80%). Aggressive lymphoma. Rapidly growing mass, avid FDG uptake.
Distinct Features
Rapid growth, usually solitary large mass, good response to R-CHOP chemotherapy. Axillary LAP frequent. Very low ADC values on DWI.
Criteria
Indolent (low-grade) lymphoma. Slow growth, localized disease, good prognosis.
Distinct Features
Smaller size, slower growth. FDG uptake may be lower than DLBCL. Bilateral involvement is rarer. Local treatment (radiotherapy) may be sufficient.
Criteria
Highly aggressive B-cell lymphoma. Very rapid growth (doubling time <24 hours), high Ki-67 index (>95%).
Distinct Features
Dramatic growth rate, tumor lysis syndrome risk, urgent chemotherapy requirement. In young patients and immunosuppressed individuals. Highest FDG uptake.
Criteria
Anaplastic large cell lymphoma originating from breast implant capsule. Associated with textured surface implants. CD30+, ALK-.
Distinct Features
Late periprosthetic effusion (fluid collection around implant) is the most common presentation. Mass form is rarer but more aggressive. Implant removal + capsulectomy is the basis of treatment. Anechoic fluid around implant on US.
Distinguishing Feature
Invasive ductal carcinoma typically shows spiculated margins, architectural distortion, and calcification. These are typically absent in lymphoma. Lymphoma may be bilateral — bilateral primary IDC is very rare.
Distinguishing Feature
Metastasis can also appear as well-defined mass but typically has a known extra-mammary primary (melanoma, lung, etc.). Axillary LAP is more prominent in lymphoma. Metastasis is usually superficial and smaller.
Distinguishing Feature
Fibroadenoma can also be a well-defined, hypoechoic mass but occurs in younger age, grows slowly, and posterior enhancement is not as prominent as in lymphoma. Fibroadenoma is usually not bilateral and does not have accompanying axillary LAP.
Urgency
urgentManagement
medicalBiopsy
NeededFollow-up
specialist-referralBreast lymphoma must be correctly diagnosed because treatment is fundamentally different from carcinoma — chemotherapy (R-CHOP for DLBCL) is the primary treatment, surgery is not indicated. Core biopsy may be diagnostic but excisional/incisional biopsy or thick-needle (14G) biopsy is preferred for evaluation of tissue architecture. Immunohistochemistry (CD20, CD3, Ki-67) is mandatory. PET-CT staging and Ann Arbor classification are required. Hematology/oncology consultation is mandatory. In suspected BIA-ALCL, cytology from fluid around the implant should be sent and CD30 staining should be requested.
Breast lymphoma treatment is chemotherapy and/or radiotherapy (not surgery). Systemic disease must be excluded for primary breast lymphoma diagnosis. Diagnosis is made by core biopsy, flow cytometry and immunohistochemistry are required. Prognosis depends on histological subtype and stage.