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Lymphoma is a rare neoplasm in the breast. In this location, it may be primary or secondary, depending on whether there is lymphoma elsewhere in the body. The most common presentation of breast lymphoma is a painless palpable mass, indistinguishable from that of breast carcinoma, although the treatment regimens for these two neoplasms differ vastly. Knowledge of the varied mammographic and sonographic presentations of breast lymphoma should prompt more frequent recognition of this unusual malignant entity. Proper diagnosis of this neoplasm is of the utmost importance to guide appropriate treatment planning and prevent unnecessary and potentially harmful surgery. We describe secondary breast lymphoma in a woman who had been diagnosed and treated for non-Hodgkin's lymphoma several years earlier.
A 49-year-old white woman presented for a bilateral diagnostic mammogram in February 2009 with complaints of a painless, palpable lump in the medial right breast. She had non-Hodgkin's lymphoma of unknown histologic subtype diagnosed and treated into remission at age 40 (2003). Approximately 1 month before presentation, a computed tomography (CT) scan demonstrated a mass within the right breast.
Routine craniocaudal and mediolateral oblique views of both breasts demonstrated scattered fibroglandular densities within the breast parenchyma (Figure (Figure11). An additional spot tangential view of the right breast over the patient's palpable area of concern (Figure (Figure22a) demonstrated a 5 cm gently lobulated, ovoid mass at the 3 o'clock position, located approximately 7 cm from the nipple (yellow circles, Figure Figure1).1). A right breast sonogram (Figure (Figure22b) demonstrated a 4 × 2 × 1 cm well-circumscribed, hypoechoic ovoid mass at the 3 o'clock position, 8 cm from the nipple, corresponding to the patient's palpable area of concern. An 0.8 cm ovoid mass at the 11 o'clock position, 8 cm from the nipple, corresponded to an intramammary lymph node (blue circle, Figure Figure1).1). In addition, sonographic evaluation of the right axilla demonstrated a 2.7 cm lymph node with a thickened cortex.
A percutaneous, ultrasound-guided core needle biopsy of the ovoid mass within the right breast was consistent with a grade I (low-grade) follicular B-cell lymphoma (Figure (Figure33). The B lymphoid cells stained positive for CD20 and CD79a, and follicular structures demonstrated a 10% positive reaction for BCL-2. A positron emission tomography (PET) scan 2 months later for restaging purposes demonstrated a hypermetabolic ovoid mass within the medial right breast, corresponding to the biopsied lesion at the patient's palpable area of concern (red circles, Figures Figures44 and and55). Additional hypermetabolic foci identified at various locations above and below the diaphragm were compatible with recurrent or residual lymphoma (Figure (Figure44). The enlarged right axillary node previously identified on the right breast sonogram showed intense hypermetabolic activity on PET scan.
The patient was treated with cyclophosphamide, vincristine, prednisone, and rituximab, and a follow-up PET scan (not shown) performed 1 month following the patient's last round of chemotherapy demonstrated interval resolution of all hypermetabolic foci previously identified, compatible with a complete therapeutic response to chemotherapy.
Breast involvement by lymphoma constitutes ≤0.5% of all mammary malignancies (1–5). The rarity of lymphoma in the breast may be attributed to its relative paucity of lymphoid tissue. Lymphomas demonstrate a bimodal age distribution, with peaks in the fourth and seventh decades of life (4, 5). Most breast lymphomas are of the non-Hodgkin's B-cell type, with diffuse large B-cell lymphoma constituting the most prevalent subtype (6).
Intramammary masses, most of which are round or oval in shape with circumscribed or gently lobulated margins, are the most common mammographic finding. Calcific deposits and spiculated margins are uniformly absent, and architectural distortion is rare (1, 4). High-grade lymphomas have been reported to manifest more frequently as diffuse breast enlargement, whereas low- to intermediate-grade neoplasms preferentially display a more nodular pattern (4, 7). Sonographically, breast lymphoma appears as a hypoechoic to almost anechoic round or oval-shaped mass with relatively well-defined margins with or without posterior acoustic enhancement (4, 6). In addition, a pseudocystic serpentine mass appearance has been documented on sonographic evaluation of two breast lymphoma cases in a study by Gal-Gombos et al (8).
Although few studies have described the magnetic resonance imaging (MRI) characteristics of breast lymphoma, certain features have been elucidated to date. Surov et al (4) and Yang et al (5) characterized these lesions as hyperintense compared with surrounding breast parenchyma on T2-weighted images and isointense on T1-weighted images. Global intense heterogeneous or homogeneous contrast enhancement was identified after the administration of intravenous gadolinium. Kinetic analysis of contrast enhancement demonstrated rapid initial signal increase, which plateaued or rapidly washed out (type 2 or type 3 kinetic curves), the findings of which are characteristic for malignancy.
In an attempt to differentiate between primary and secondary breast lymphoma, a few distinguishing characteristics may be helpful, though they are not pathognomonic in and of themselves. In contrast to primary disease, masses in secondary breast lymphoma often demonstrate smaller diameters upon initial presentation. Sabaté et al (7) indicated that the average diameter of a mass in secondary breast lymphoma measured 2.8 cm compared with an average of 4.6 cm for primary breast lymphoma. This finding may be partially explained by the fact that the duration of symptoms prior to clinical and radiologic examination may be shorter in patients in whom lymphomatous disease is known. Likewise, the number of intramammary masses has been reported to be higher in secondary than in primary breast lymphoma (4), in keeping with the overall extent of primary versus secondary lymphomatous disease. Parenchymal breast involvement in association with bilateral axillary lymph node enlargement may be suggestive of lymphoma, particularly secondary breast lymphoma, although widespread metastatic breast carcinoma could also have a similar presentation (7).
Treatment of breast lymphoma remains somewhat controversial; however, certain guidelines have been elucidated. In a study by Fruchart et al (1), all patients undergoing mastectomy, either alone or in association with chemotherapy, died of their lymphoma. It has been postulated that this may have resulted from delay of appropriate systemic treatment. Correct diagnosis with tissue sampling is therefore of the utmost importance to prevent the morbidity and mortality associated with unnecessary surgery. Alternatively, multiple studies (1, 7) have suggested a treatment regimen consisting of combination chemotherapy with or without concurrent radiotherapy.