Primary breast lymphoma (PBL) is rare, constituting 0.04–0.53% of malignant breast neoplasms and 1.6% of extranodal lymphoma [1, 2]. However, PBL incidence has recently increased, especially in young women, i.e., those aged younger than 50 . Criteria for the histological diagnosis of PBL were suggested by Wiseman et al , and it requires a close association between mammary tissue and lymphomatous infiltration. There should be no evidence of concurrent systemic lymphoma or leukemia, while ipsilateral axillary node involvement does not rule out a PBL diagnosis. It is widely recognized that radiologic findings are generally nonspecific for breast lymphoma [5, 6], probably reflecting a variety of histological patterns with various degrees in infiltration into breast tissue, nodule formation, and/or stromal sclerosis.
PBL is generally B-type, with diffuse large B cell lymphoma (DLBCL) being the most common . Lymphoblastic lymphoma (LBL) is relatively rare, accounting for approximately 2% in non-Hodgkin’s disease cases . The frequency of B cell-LBL (B-LBL) is considered to be around 10–15% in LBL, making the B-LBL in our case extremely rare. Histologically, differentiation between B-LBL and T cell-LBL (T-LBL) is difficult. Tumor cells are frequently arranged in a linear pattern, resembling infiltrating lobular breast carcinoma. The starry-sky pattern is also known to be common in this type of lymphoma. Moreover, tumor cells are reactive for TdT and PAX5, markers of lymphoblastic lymphoma on immunohistochemistry. Meanwhile, the major types of lymphoma in children are Burkitt lymphoma, DLBCL, LBL, and anaplastic large-cell lymphoma, comprising 90% of all non-Hodgkin’s disease cases . Children with LBL are offered the same treatments as patients with acute lymphoblastic leukemia. Usually, combination chemotherapy is effective, and 5-year event-free survival is expected to be more than 90%.
As to malignant breast tumors in children, occurrence rates are reportedly quite low, regardless of tumor types. According to the surveillance, epidemiology and end results (SEER) data, the age-adjusted incidence of breast cancer and sarcoma were 0.03 and 0.06 cases, respectively, per 100,000 females age 19 years and younger . PBL is also extremely rare, and the actual occurrence rate is unknown due to a lack of accumulated data. Furthermore, malignant breast tumors in children might be more likely than breast cancer, sarcoma, or PBL to be metastatic lesions . Rhabdomyosarcoma, neuroblastoma, Ewing sarcoma, melanoma, and renal cell carcinoma are primary tumors reportedly known to be prone to metastasize. Moreover, malignant lymphoma originating from other organs can metastasize to breast tissue and form a mass. Breast lymphomas, representing secondary malignant involvement, are much more frequent than PBL . If a patient has a medical history of these diseases, physicians should take this into account when examining breast tumors.
We herein report a malignant lymphoma of the breast arisen in an adolescent female. To the best of our knowledge, this is the youngest case with primary breast non-Hodgkin’s lymphoma reported to date.