Background
Monoclonal B cell lymphocytosis (MBL) is defined as presence of clonal b cell population that is fewer than 5 × 10(9)/L B-cells in peripheral blood and no other signs of a lymphoproliferative disorder. Patients with MBL are usually monitored with periodic history, physical exam and blood counts. Here we presented a case of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) in breast in a patient with a history of MBL.
Case Presentation
68-year-old male with history of MBL underwent mammogram for breast mass. It showed suspicious 4.4 x 1.6 cm solid and cystic lesion containing a 1.7 x 0.9 x 1.8 cm solid hypervascular mass. Patient underwent left breast mass excision. Histologic sections focus of ADH involving papilloma with uninvolved margins. Lymphoid infiltrates noted had CLL/SLL immunophenotype and that it consists mostly of small B cells positive for CD5, CD20, CD23, CD43, Bcl-2, LEF1. CT CAP and PET/CT were negative for lymphadenopathy. Bone marrow biopsy showed marrow involvement by mature B-cell lymphoproliferative process, immunophenotypically consistent with CLL/SLL. As intra-ductal papilloma completely excised and hemogram was normal tumor board recommended surveillance only for CLL/SLL.
Discussion
MBL can progress to CLL, but it can rarely be presented as an extra-nodal mass in solid organs. We described a case of MBL that progressed to CLL/ SLL in breast mass in a male patient. This is the first reported case in literature where MBL progressed to CLL/ SLL of breast without lymphadenopathy. Upon literature review 8 case reports were found where CLL/SLL were described in breast tissue. 7 of them were in females and 1 one was in male. Two patients had CLL before breast mass but none of them had a history of MBL. 3 described cases in females had CLL/SLL infiltration of breast along with invasive ductal carcinoma. So, a patient with MBL can progress to involve solid organs despite no absolute lymphocytosis and should be considered in differentials of a new mass. Although more common in females, but it can occur in males as well. It’s important to consider the possibility of both CLL/SLL and breast cancer existing simultaneously.