Role of fine-needle aspiration cytology in breast lymphoma

Lymphomas of the breast are rare and may mimic carcinoma clinically. We investigated the ability of fine-needle aspiration (FNA) biopsy combined with adjunctive flow cytometry (FC), immunofluorescence microscopy (IFM), and immunocytochemistry (ICH) to diagnose and eventually subclassify lymphomas of the breast according to the Revised European American Lymphoma/World Health Organization classification. We retrieved 21 breast aspirates from 19 patients with a cytologic diagnosis of lymphoma or plasmacytoma over a 10-year period (1992-2002), excluding 98 benign intramammary lymph nodes and 1 atypical lymphohistiocytic proliferation (Rosai Dorfman disease). FC was performed in 15/21 aspirates, IFM in 1/21, ICH in 3/21. Histologic follow-up (HF) was obtained for 10 patients, most of them with primary lymphoma. For the remaining nine patients without HF, flow cytometric analysis, comparative morphology, or remission after chemotherapy regimens supported the cytologic diagnosis. Of 19 patients, 11 patients had a secondary lymphoma (SL) and 8 patients had a primary lymphoma (PL). FNA and FC/IFM/ICH classified 7/8 PLs as B-cell lymphomas and 1/8 PLs as plasmacytoma. However, FNA could only subclassify 3 of 8 PLs. FNA and/or FC subclassified accurately 10/11 SLs. All cases were accurately immunophenotyped as B-, T-cell non-Hodgkin's lymphomas or plasmacytoma. World Health Organization classification was achieved in 3/8 PLs (42%) and 10/11 SLs (91%; P = 0.04). Subclassification (which has an impact on long-term management and prognosis) was significantly better in SL, when a previous histologic diagnosis had already been made, when compared to PL, of which 5/8 cases (62.5%) could not be accurately classified.