Primary Extranodal Marginal Zone Lymphoma of the Breast: A Case Report Highlighting the Clinicopathological Paradigm of an Indolent B-Cell Neoplasm

Abstract

Primary or secondary lymphoma of the breast is an uncommon entity, accounting for less than 0.5% of all breast malignancies and approximately 1-2% of extranodal lymphomas. Diffuse Large B-Cell Lymphoma (DLBCL) is the most frequently reported histological subtype. Marginal zone B-cell lymphoma involving the breast is exceedingly rare, particularly in patients with a prior history of DLBCL. The present case describes an unusual occurrence of synchronous second primary lymphoid neoplasm of breast in a patient previously treated for DLBCL, highlighting its diagnostic rarity. The authors report a rare case of a 57-year-old female with a past history of DLBCL, diagnosed two years ago on histopathological examination of excised lymph node over left neck region. Patient received chemoradiotherapy post-diagnosis and had recovered completely. She now presented with bilateral breast lumps and an additional lump in the left axillary region. An initial histopathological diagnosis of Non-Hodgkin’s Lymphoma of breast was made which needed further immunophenotypic characterisation. Immunohistochemistry (IHC) was done which showed strong positivity for CD45, CD19, CD20, PAX5, Bcl2, Ki-67 which confirmed the diagnosis of Marginal Zone B-cell Lymphoma, emphasising diagnostic challenges. Post histopathological diagnosis and immunohistochemistry, patient received targeted therapy along with chemotherapy to which she responded well. The present case is noteworthy because of the uncommon involvement of both breasts and the axillary region in a patient with a prior diagnosis of DLBCL, suggesting potential disease recurrence or extranodal extension.