Primary Breast Lymphoma

Abstract

The term “primary breast lymphoma” (PBL) is used to define a malignant lymphoma primarily occurring in the breast in the absence of previously detected lymphoma localizations [1].

PBL is a rare disease, accounting for only 0.4-0.5% of all breast malignancies, 0.38-0.7% of all non-Hodgkin lymphomas (NHL), and 1.7-2.2% of extranodal NHL. The median age of patients with diagnosed PBL ranges from 60 to 65 years [1-12]. The disease occurs almost exclusively in women. Bilateral breast involvement accounts for 11% of all breast lymphomas [13] or 5% according to Ryan et al. [11]. This rare situation is especially observed during pregnancy or postpartum, suggesting that tumour growth is influenced by hormonal stimulation.

Breast lymphoid cells probably originate in mucosa-associated lymphoid tissue (MALT) [14]. PBL may also originate from lymphatic tissue present within the breast adjacent to ducts and lobules, or from intramammary lymph nodes [15, 16].

More than 80% of PBL are B-cell lymphomas, mostly CD20+. The most frequent histopathologic types are: diffuse large B-cell lymphoma (DLBCL) which accounts for up to 50% of all PBL, follicular lymphoma (FL) – 15%, MALT lymphoma – 12.2%, Burkitt’s lymphoma (BL) and Burkitt-like lymphoma – 10.3% [17]. Other histological types of PBL include marginal zone lymphoma (MZL), small lymphocytic lymphoma (SLL), and anaplastic large cell lymphoma (ALCL).

Diffuse large B-cell lymphoma (DLBCL) is the most common histological diagnosis. These lymphomas have been shown to be of a non-germinal centre B-cell phenotype with a high proliferation index and are thought to be associated with a poor outcome [18]. There is a close association between ALCL and silicone breast implants [19, 20].

Burkitt’s lymphoma is observed particularly in pregnant or lactating women and HIV-seropositive patients. The clinical presentation of PBL and the radiological features are usually no different from those of carcinoma of the breast. PBL is usually classified according to the Ann Arbor staging system. Other diagnostic criteria for PBL were described by Wiseman and Liao in 1972 [21]. According to the last classification, the clinical site of presentation is the breast. A history of previous lymphoma or evidence of widespread disease are absent at diagnosis. There is present close association of lymphoma to breast tissue in the pathologic specimen. Ipsilateral lymph nodes may be involved. This definition of PBL comprises only tumours being in stage I (lymphoma limited to the breast) and stage II (lymphoma limited to the breast and axillary lymph nodes) and not to tumours originating from non-breast sites.