[Primary lymphoma of breast: a clinicopathologic and prognostic study of 40 cases].

Objective: To study the clinicopathologic features and prognosis of primary lymphoma of breast.

Methods: Forty cases of primary breast lymphoma, diagnosed according to the 2008 World Health Organization classification of hematopoietic and lymphoid tumors, were retrospectively studied. Immunohistochemistry was performed by SP method. The follow-up data were analyzed.

Results: (1) All the patients were females and the median age was 47 years. Unilateral and bilateral breast involvement were noted in 36 and 4 patients, respectively. The number of tumor were 31 cases (77.5%, 31/40) less than 3, and 9 cases (22.5%, 9/40) were 3 and more than 3. According to Ann Arbor staging system, 33 cases (82.5%) were in stage I to II and 7 cases (17.5%) in stage III to IV. The level of LDH in 9 cases (24.3%, 9/37) went up. For ECOG scores, 34 cases (85.0%) were 0 to 1 score and 6 cases (15.0%) were more than 2 scores. With respect to international prognostic index, 83.8% (31/37) were of score 0 to 2 and 16.2% (6/37) were of score 3 and more than 3. The axillary lymph nodes of 21 patients (53.8%, 21/39) were involved by the malignancy. (2) Histologically, 38 cases (95.0%, 38/40) were classified as B-cell lymphoma [including 27 cases (67.5%) of diffuse large B-cell lymphoma, 8 cases (20.0%) of mucosa-associated lymphoid tissue lymphoma, 2 cases of follicular lymphoma and 1 case of lymphoplasmacytic lymphoma]. The remaining cases included one case of peripheral T-cell lymphoma and one case of lymphoblastic lymphoma. Immunohistochemically, expression of CD20+/- CD79a were demonstrated in the 38 cases (95.0%) of B-cell lymphoma. The staining for CK was negative in all cases. In 33 cases, the positive rates of MUM-1, bcl-6 and bcl-2 were 57.6% (19/33), 30.3% (10/33) and 72.7% (24/33), respectively. Three cases were germinal center B cell phenotype and 21 cases were non-germinal center B cell phenotype. (3) Follow-up information was available in 37 patients (92.5%, 37/40). Twenty-three patients (62.2%, 23/37) were still alive and fourteen ones (37.8%, 14/37) died. For the 27 cases with diffuse large B-cell lymphoma, the five-year and disease-free survival rates were 48.0% and 36.0%, respectively.

Conclusions: Primary breast lymphoma is a rare disease entity. Diffuse large B-cell lymphoma is the commonest histologic type and the majority show a non-germinal center B cell phenotype. The level of LDH, number of tumor and international prognostic index are of prognostic significance.