Breast Lymphoma: An unusual case of breast lumps in a young adult woman

A 31-year-old woman presents with a 2-month history of bilateral, palpable, painless, hard consistency, breast lumps. Four years earlier, she had a non-Hodgkin peripheral T-cell lymphoma not otherwise specified (NOS), treated with chemotherapy followed by an autologous bone marrow transplant, with no evidence of disease afterwards.

Radiotherapy was not performed.

Mediolateral oblique and craniocaudal (Fig. 1) mammograms showed two high-density irregular masses with indistinct margins, without calcifications or other associated findings, located in the upper-outer quadrant  (UOQ) of the left breast and in the upper-inner quadrant (UIQ) of the right breast. 

Breast ultrasound (US) revealed two corresponding irregular masses with microlobulated margins (Fig. 2). Both lesions showed posterior enhancement and internal vascularization in Doppler-US assessment (Fig. 3). Neither additional lesions nor axillary or internal mammary lymphadenopathies were found.

Magnetic resonance imaging showed two irregular T2-hyperintense masses (Fig. 4), with irregular margins, located in the left breast UOQ and in the right breast UIQ. These had diffusion restriction demonstrated by a very high signal on high b-value images (b=800 s/mm2) and a very low signal on ADC-map (Fig. 5) , and heterogeneous contrast enhancement with a relatively fast initial uptake followed by a plateau towards the delayed phase of the study (Fig. 6). No associated features such as nipple retraction, sking changes or adenopathies were found.

A core biopsy was performed using a 12-gauge needle (Fig. 7), retrieving three fragments from each lesion. Pathologic examination (Fig. 8 and 9) established the diagnosis of non-Hodgkin peripheral T-cell lymphoma NOS.

At baseline computed tomography (CT), no signs of extramammary disease were present.

After the final diagnosis, the patient began chemotherapy according to DHAP protocol, including dexamethasone, cytarabine and cisplatin. Reevaluation after three cycles of DHAP-chemotherapy, with positron emission tomography (PET)-CT, showed no signs of metabolically active disease. By the time of this publication, allogenic bone marrow is being considered as the next step in the patient´s management.

Background

Breast lymphoma comprises primary and secondary breast lymphoma (PBL and SBL). PBL refers to lymphoma arising in the breast without previously diagnosed extramammary lymphoma or simultaneous widespread disease. The original criteria for PBL, suggested by Wiseman and Liao [1], encompasses: the availability of adequate pathology material; both mammary tissue and lymphomatous infiltrate are present; absence of widespread disease or preceding extramammary lymphoma; ipsilateral axillary node involvement is considered acceptable. Updated additional criteria include ipsilateral supraclavicular lymph nodes equating to regional disease [2]. PBL typically manifests as a palpable abnormality and a solitary imaging finding. In contrast, SBL is more often clinically occult and manifests as multiple masses at imaging.

Although SBL is slightly more common than PBL, both are exceedingly rare entities, probably due to the scarcity of lymphoid tissue in the breast [2]. 

Clinical Perspective

The most typical symptom of breast lymphoma is a painless, palpable mass [2]. Inflammatory changes can be found in high-grade lymphomas. Enlarged axillary lymph nodes are clinically evident in 30%–50% of patients [4]. Nipple retraction or nipple discharge is unusual [3].

The median age of presentation of breast lymphoma is between 60-65 years for SBL and 60-70 for PBL [2].  It is unusual at younger ages, as in our case.

Imaging Perspective

Breast lymphoma, either PBL or SBL, does not present with any pathognomonic imaging features at mammography, US, or MRI.

Mammography usually shows a solitary, oval or round, noncalcified mass [3,4]. Less than 10% of cases have multiple masses, and about 10% have bilateral involvement, both more common with SBL [3]. Calcifications, spiculations, or architectural distortions, are extremely rare with lymphoma [2]. US usually shows irregular, hypoechoic, and hypervascular masses with indistinct margins or an echogenic boundary [3]. These masses are generally parallel in axis [3].

MRI generally shows a round or oval mass hypointense or isointense in T1-weighted imaging and with areas of hyperintensity at T2-weighted imaging [3]. Dynamic contrast-enhanced MR imaging typically exhibits rapid initial enhancement and plateau or a washout delayed phase enhancement [2,4].

PET-CT is the only modality that secures this diagnosis showing avid homogeneous hypermetabolism [4]. It is a highly sensitive and specific method in evaluating treatment response, tumour staging, and assessing additional sites of involvement [2].

Imaging-guided core needle biopsy or excisional biopsy is mandatory for definitive diagnosis. Most breast lymphomas (94%) are of the B-cell type, and only 6% are of the T-cell type [5], as in our case.

Outcome

Breast lymphoma prognosis is related to clinical stage and histological subtype. Radiation and systemic therapies achieve good control of the disease, and surgery is usually not required [6]. Therefore to avoid unnecessary aggressive treatments, it is crucial to distinguish lymphoma from other, more common, mammary neoplasms.