Hematolymphoid Neoplasms Involving the Breast: A Single Institution Clinicopathologic Study of 59 Patients

Background: Breast hematopoietic neoplasms (BHN) are rare and may be either primarily (PBHN) or secondarily (SBHN) involving breast tissue. Due to the widespread use of needle biopsy for initial diagnosis of breast lesions, knowledge of their presentation, radiologic aspects, histomorphology, and outcomes are critical for seeking appropriate hematopathology consultation. Herein, we present our clinical experience as an academic institution and referral center of BHN in the past 20 years. Methods/Design: We identified 59 patients diagnosed at the University of Chicago Medical Center between 2002-2021. Demographic, pathologic, radiologic, therapy, relapse data, and vital status were abstracted. Data were examined using univariable statistics with event-free and overall survival (EFS, OS) as primary outcomes examined with the lymphoma subgroup using Cox PH regression adjusted for age. Results: The cases included 27 (46%) PBHN and 32 (54%) SBHN in a cohort comprising 93% females, mostly white (56%) (Table 1). The mean age at diagnosis was 58.8 years. Lymphomas were the most frequent BHN (Figure 1). Examining the lymphoma cohort (86.4% of all cases), patients with primary breast lymphomas (PBL) were significantly older than those with secondary breast lymphomas (SBL) (61.2 vs. 49.8 yrs, p<0.02). The most frequent lymphomas were extranodal marginal zone lymphoma (MZL) (32.2%) and diffuse large B-cell lymphoma/high grade B-cell lymphoma, not otherwise specified (DLBCL/HGBCL, NOS) (33.9%). Over half of MZLs and DLBCLs were primary in the breast. 5 of 59 patients presented with concurrent breast carcinoma (Table 2). Although 2 patients had breast implants, no cases of implant-associated anaplastic large cell lymphoma (ALCL) were diagnosed. Within B-cell lymphomas, 20 (37%) were high grade with inferior 10-yr overall survival (OS) (age-adjusted HR 5.47, 95% CI 1.38, 21.64) compared to low-grade without any impact on event free survival (EFS) (Figure 2). Conclusion: This is one of the largest cohorts so far describing HNs in the breast. DLBCL and MZL remain the most common lymphomas involving this site. The majority of patients were diagnosed via core needle biopsy (CNB) and did not have a prior diagnosis of a BHN. Radiographically, the presentation may closely mimic breast carcinoma.