MRI features of breast lymphoma: preliminary experience in seven cases

PURPOSE

We aimed to evaluate the imaging features of breast lymphoma using magnetic resonance imaging (MRI).

METHODS

This retrospective study consisted of seven patients with pathologically confirmed breast lymphoma. The breast lymphomas were primary in six patients and secondary in one patient. All patients underwent preoperative dynamic contrast-enhanced MRI and one underwent additional diffusion-weighted imaging (DWI) with a b value of 600 s/mm². Morphologic characteristics, enhancement features, and apparent diffusion coefficient (ADC) values were reviewed.

RESULTS

On MRI, three patients presented with a single mass, one with two masses, two with multiple masses, and one with a single mass and a contralateral focal enhancement. The MRI features of the eight biopsied masses in seven patients were analyzed. On MRI, the margins were irregular in six masses (75%) and spiculated in two (25%). Seven masses (87.5%) displayed homogeneous internal enhancement, while one (12.5%) showed rim enhancement. Seven masses (87.5%) showed a washout pattern and one (12.5%) showed a plateau pattern. The penetrating vessel sign was found in two masses (25%). One patient with two masses underwent DWI. Both masses showed hyperintense signal on DWI with ADC values of 0.867×10⁻³ mm²/s and 0.732×10⁻³ mm²/s, respectively.

CONCLUSION

Breast lymphoma commonly presents as a homogeneously enhancing mass with irregular margins and displays a washout curve pattern on dynamic MRI. A low ADC value may also indicate a possible diagnosis of breast lymphoma.Breast lymphoma, which constitutes only 0.04%–0.5% of all breast malignancies (1), can be divided into primary or secondary breast lymphoma (2). The majority of breast lymphomas are diffuse large B-cell lymphoma (3). The spontaneous regression of a breast lymphoma is rare and the five-year overall survival rate is 53% (1, 4). Early-stage identification and the use of radiotherapy are favorable prognostic factors, while mastectomy is associated with a poorer survival (1, 5). Therefore, a preoperative diagnosis of breast lymphoma would mean an earlier diagnosis and likely avoid unnecessary aggressive procedures.Previous studies demonstrated mammographic and ultrasonographic findings of breast lymphoma (6–8). Most lesions were high-density masses without spiculated margins and calcifications on mammography and noncircumscribed hypoechoic masses on ultrasonography (6–8). However, none were pathognomonic.Data on the magnetic resonance imaging (MRI) of breast lymphoma are limited to some single case reports (4, 7, 9–19) and small sample size case series (8, 20–23). The morphology and time-signal intensity curve (TIC) of breast lymphoma on MRI are variable. Diffusion-weighted imaging (DWI) is a functional imaging technique that is useful for distinguishing lymphoma from other malignant tumors in other systems (24, 25). However, to the best of our knowledge, the value of DWI in differentiating breast lymphoma from other malignant breast lesions has not been discussed. Therefore, the purpose of this study is to assess the MRI and DWI features of breast lymphoma.