Primary Hairy Cell Leukemia/Lymphoma of the Breast: A Case Report and Review of the Literature

Abstract

Hairy cell leukemia/lymphoma (HCL) is a rare B-cell neoplasm primarily involving spleen, bone marrow, and blood. However, other sites of primary involvement do occur and can present a diagnostic and therapeutic challenge. We present an unusual case of HCL involving predominantly the breast that was diagnosed as an incidental finding during an elective reduction mammoplasty in an otherwise healthy asymptomatic woman. Bone marrow performed for staging revealed limited involvement by HCL. Notably, there was no splenomegaly and/or involvement of other extramedullary sites. The peripheral blood revealed minimal involvement detected by flow cytometry. Extensive immunohistochemical studies supported by positive BRAF V600E mutational status confirmed the diagnosis of HCL. The patient remains asymptomatic without treatment one year following the diagnosis. This is the first case of a well-documented HCL presenting primarily in the breast in an asymptomatic patient. We review the literature on extramedullary, extrasplenic involvement by HCL and discuss the diagnostic challenges as well as the utility of immunohistochemistry and molecular studies in the diagnosis of atypical presentations of HCL.

Morphological and immunophenotypical features of hairy cell leukaemia involving lymph nodes and extranodal tissues

“…This is particularly true in the evaluation of nodal/extranodal biopsies from patients without a preceding diagnosis or clinical features of HCL. Indeed, in several reports, patients with nodal/extranodal presentations of HCL exhibited normal peripheral counts and lacked splenomegaly and, in some cases, no marrow infiltration was detected by standard iliac crest sampling . Therefore, the goal of this study was to provide a comprehensive morphological, immunophenotypical and molecular analysis of HCL involving nodal and extranodal tissues in order to facilitate pathological recognition of a rarely sampled and probably underappreciated manifestation of HCL.…”

Hairy Cell Lymphoma: A Potentially Under-Recognized Entity

“…However, a variant form of HCL (HCL-v), accounting for approximately 10% of all cases, with similar morphologic features but a different IHC staining pattern and a negative BRAFV600E mutation status has also been well described. This disease variant does not respond to cladribine therapy like HCL-c. 4,5 Other unusual presentations of HCL-c involving non-lymphoid, non-reticuloendothelial tissue, 6 including bones, 7 soft tissues, 8 and the brain, 9 have also been reported; however, these have been in the setting of other classic clinical features of HCL. Occasionally, usually at advanced stages, HCL-c may involve lymph nodes, most often in the abdomen or retroperitoneum.…”

Hairy Cell Leukemia Presenting with a Lytic Bone Lesion

“…Th e disease has distinct morphologic, immunohistochemical, fl ow cytometric, and molecular fi ndings (1). HCL is characterized by expression of B-cell markers (CD19, CD20, CD22) as well as CD11c, CD25, CD103, DBA44, and annexin A1 (2). HCL has a male predominance and usually occurs in patients over 50 years old (3).…”

“…Second, the patient did not present with pancytopenia, which is common at presentation and reported in 50% to 70% of patients with HCL (1, 2). Th ird, HCL presenting as a lytic bone lesion is very unusual (2,8). Skeletal complications can occur as a consequence of HCL, with a reported incidence of 3% and presentation about 20 months after initial diagnosis, but to present with skeletal abnormalities is very rare (9).…”