Background: Lymphatic mapping of axillary breast cancer metastases in the presence of concomitant lymphoproliferative disease is still a controversial topic. Previous reports have postulated that tumor collision in the lymph nodes could lead to false-negative results of sentinel lymph node biopsy, leading to erroneous staging.
Case Report: We present the case of a 66-year-old woman with infiltrating ductal breast carcinoma and small lymphocytic lymphoma in whom we performed a lumpectomy and sentinel lymph node biopsy with Technetium-99 and 1% methylene blue, followed by axillary lymph node dissection regardless of the intraoperative status, which was negative. Final pathology confirmed the absence of lymph node metastases.
Conclusions: Previously published cases reported correct assessment of SLNB in patients with concomitant small lymphocytic lymphoma and breast carcinoma. We postulate a possible pathological explanation for this: lymphoid cell clusters with pseudofollicles or proliferative centers of small lymphocytic lymphoma are localized outside the nodal sinuses of the lymph node, maintaining its capability of draining, and thus, the feasibility of SLNB in these patients, as in the presented case.

Keywords: Sentinel Lymph Node Biopsy, lymphoid malignancies