[Clinicopathologic features of breast lymphoma in core needle biopsy]

Objective: To investigate the clinicopathologic features and differential diagnosis of breast lymphoma in core needle biopsy. Methods: Seventy-two cases of breast lymphoma in core needle biopsy between 2011 and 2016 were extracted from the pathology database of Fudan University Shanghai Cancer Center. The clinicopathologic features were analyzed. The histological diagnosis of the tumors was based on the WHO classifications of tumors of hematopoietic and lymphoid tissues. Immunohistochemistry and molecular methods were performed to detect related antigens and genes. Results: Seventy-one patients were female and one was male. The median age was 54 years. The tumors were located in the right breast in 32 (44.4%) patients and in the left breast in 40 (55.6%) patients. Seven patients had a previous history of lymphoma. Most of the cases presented as a single and painless breast mass. Sixty-three patients received systemic treatment, and nine patients received systemic therapy after excision. The common morphological feature was that single tumor cells infiltrated the stroma, without cohesiveness between tumor cells, and lacking glandular or nested epithelioid structures. The normal ductal and lobular structures of the mammary gland were typically preserved. The tumor cells in some cases were distributed in single rows, and should be differentiated from invasive carcinoma. All cases were positive for LCA, negative for CK. Sixty-eight cases were classified as B-cell lymphoma, including 63 cases (87.5%) of diffuse large B-cell lymphoma (DLBCL; including 3 cases of EBV-positive DLBCL and 60 cases of DLBCL, NOS), two cases of Burkitt lymphoma, one case of mantle cell lymphoma, one case of extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue and one case of precursor B lymphoblastic leukemia/lymphoma. The remaining cases included two peripheral T-cell lymphoma (NOS), one extranodal NK/T cell lymphoma, nasal type and one myeloid sarcoma. In 63 cases of DLBCL, 22 cases (34.9%) expressed germinal center B-cell-like (GCB) phenotype and 41 cases (65.1%) showed non-germinal center B-cell-like (non-GCB) phenotype. Conclusions: Core needle biopsy could be the preferred method for diagnosis of breast lymphoma. Diffuse large B-cell lymphoma is the most common histologic type of breast lymphoma, and non-GCB subtype is more frequent than GCB subtype.