Teaching Case

A 78-year-old female patient underwent mammography and ultrasonography for characterisation of a painless lump on right breast retroareolar area. Her past clinical history included a low-risk B-cell chronic lymphocytic leukemia (Rai stage 0) and hypertension. Her past surgical history included left breast tumorectomy for benign pathology.

Mammography revealed a global asymmetry on the right breast (Fig. 1). A central architectural distortion on the left breast was also noted in concordance with past history of left breast surgery.
A complementary tomosynthesis in MLO projection highlighted the presence of the asymmetry described above (Fig. 2).
Ultrasonography showed multiple irregular hypoechoic nodules with indistinct margins in the lateral and upper quadrants of the right breast, as a correlate for mammography findings (Fig. 3). Multiple small bilateral axillary lymph nodes were noted, showing uniform cortex thicker than 3 mm and minor surface lobulations – type 3 in Bedi classification (Fig.4).
The contrast-enhanced breast magnetic resonance revealed a non-mass heterogeneous enhancement in the referred quadrants, with an infiltrative pattern rather than a mass effect (Figs. 5, 6 and 7).  The enhancement areas showed a type II kinetics curve and restricted diffusion (Fig.8). A BIRADS 4c was attributed.

An ultrasound-guided core biopsy was performed and the pathological analysis revealed a periductal infiltration of a monotonous lymphoid population, constituted by small lymphocytes CD20+, CD3-, CD5+, CD23+, CD10-, BCL2+, BCL6+ e CCND1- compatible with lymphocytic lymphoma/lymphocytic B-cell chronic leukemia.
Background
Lymphoproliferative diseases, melanoma, lung cancer and gynecological malignancies are the most frequent non-primary malignant tumours affecting breasts [1, 2]. Of these, lymphomas account for 17%, making them the most common [3].
The true prevalence of breast lymphoma is difficult to determine.  In a relatively recent study, the prevalence of breast lymphoma was 1.6% of all identified cases with non-Hodgkin lymphoma [4]. The most frequent types of lymphoma affecting breasts are follicular lymphoma and diffuse large B-cell lymphoma [5]. B-cell chronic lymphocytic leukemia/lymphocytic lymphoma rarely involves the breast [5].
Clinical Perspective
The most common presentation of breast lymphoma is a painless lesion in the breast [6]. Nipple retraction, skin thickening, and nipple discharge are rare [7]. Lymph node involvement has been variably documented and is often bilateral [8].
Imaging Perspective
Mammographic findings are unspecific [9] and can be unilateral as in this case.
Ultrasonography of lymphoma is also not specific, the most common finding being homogeneous hypoechoic or heterogeneous mixed hypo-to hyperechoic masses [9]. MRI features of breast lymphoma are variable. After intravenous administration of gadolinium, a marked inhomogeneous enhancement may be seen [9].
Despite unilateral breast findings in this case, the presence of uniformly enlarged bilateral lymph nodes, together with history of haematologic malignancy, constituted major diagnostic clues in this case. Breast biopsy confirmed the diagnosis.
Outcome
Because lymphocytic lymphoma/lymphocytic chronic B-cell leukemia is a slow growing disease and in absence of symptoms, ‘watchful waiting’ was the choice for this patient. If symptoms develop, treatment may be started.
Take Home Message /Teaching Points
Breast lymphoma diagnosis should be kept in mind and requires histological confirmation from biopsy, in order to distinguish it from breast carcinoma. Accurate diagnosis is crucial for implementing correct treatment and prevent unnecessary surgery [10].

Written informed patient consent for publication has been obtained.