694 Arch Pathol Lab Med—Vol 129, May 2005 Primary Breast Lymphoma Cytologic Diagnosis—Vardar et al Primary Breast Lymphoma Cytologic Diagnosis Enver Vardar, MD; Guliz Ozkok, MD; Mehtap Cetinel, MD; Hakan Postaci, MD ● Primary non-Hodgkin lymphoma of the breast is a rare pathology, and bilateral involvement is exceptional.We re- port a case of bilateral primary non-Hodgkin lymphoma of the breast in a 40-year-old woman. Predominantly atypical lymphocytes and rare plasma cells were found in the mi- croscopic evaluation of the fine-needle aspiration biopsy of the right and left breasts. Microscopic findings of the incisional biopsy of the left breast were in accordance with non-Hodgkin diffuse large B-cell lymphoma. The patient received systemic chemotherapy and is alive with no evi- dence of recurrence for 2 years. (Arch Pathol Lab Med. 2005;129:694–696) P rimary breast lymphoma (PBL) is a rare disease, which comprises 0.04% to 0.53% of all primary malignant tu- mors of the breast and 2.2% of extranodal lymphomas. 1–4 Most breast lymphomas are of diffuse B-cell type. 1,3 The prognosis in PBLs is related to the cell type and clinical stage, as in lymphomas located elsewhere. 3 Differentiation of PBLs from other breast tumors is difficult preoperatively, especially with limited materials such as fine-needle aspi- ration biopsy (FNAB), in which they can resemble breast carcinoma. 5,6 We report a case that was diagnosed as ma- lignant on FNAB and that was assigned the diagnosis of breast lymphoma on microscopic evaluation of the incision- al biopsy material. REPORT OF A CASE A 40-year-old woman presented with the complaint of a pal- pable mass in her left breast. Increased density in both breasts was found during her mammographic evaluation. This investi- gation was followed by bilateral breast ultrasonography, in which hypoechoic masses were detected; the dimensions of the masses were 5.7  5.1 cm in the left breast and 2.1  2.1 cm in the right. An FNAB was performed on both breasts. In evaluating the he- matoxylin-eosin–stained cytologic samples, a highly cellular ap- pearance was observed in a background rich in erythrocytes (Fig- ure 1). The tumor cells were dispersed mostly as single cells and less often as groups consisting of a few cells. Groups consisting of numerous cells also were observed. Nuclei of the tumor cells showed hyperchromasia, and they were pleomorphic and larger than the lymphocytes in the background (Figure 2). When the diagnosis of the FNAB was reported as malignant cytology pos- sibly consistent with lobular neoplasm, an incisional biopsy was performed on both breasts. Accepted for publication November 8, 2004. From the Department of Pathology, SSK IzmirTeaching Hospital, Iz- mir, Turkey. The authors have no relevant financial interest in the products or companies described in this article. Reprints: Enver Vardar, MD, 915 Sok. No. 172Yesil Evler Sitesi, Os- mangazi–Bornova–Izmir, Turkey (e-mail: envervardar@ttnet.net.tr). PATHOLOGIC FINDINGS The tissue samples had an unremarkable appearance macroscopically, demonstrating ‘‘lobulitis.’’ A month after the biopsy, the incisional biopsy of the left breast was re- peated because progression of the localized masses in both breasts continued. The macroscopic appearance of the biopsy material measured 3.5  2.5  1 cm, including mature adipose tissue in some parts, and mixed gray- white areas were also observed. Microscopic examination of the tissue sections revealed tumor cells arranged in cir- cular contoured groups in all areas, partly infiltrating the lobular structures (Figure 3). The tumor cells, which were present at the surgical margins, showed scant cytoplasm, nuclear hyperchromasia, and pleomorphism. Mitotic fig- ures were also remarkable. The lobular architecture was preserved in some parts of the lobular infiltration areas; however, these lobular structures were infiltrated with tu- mor cells. Most of the acinar structures were effaced, while only a few were preserved. Most of the tumor cells were larger than the nuclei of the active histiocytes that were observed in some parts and/or larger than the nuclei of the capillary endothelial cells. Immunohistochemically, the tumor cells showed abun- dant positivity with leukocyte common antigen (Dako- Cytomation, Glostrup, Denmark) and CD20 (Dako- Cytomation) (Figure 4). The few mature lymphocytes were stained with CD45RO (DakoCytomation). No staining oc- curred with pancytokeratin, epithelial membrane antigen, S100, neuron-specific enolase, vimentin, or HMB-45 in tu- mor cells. With these histologic and immunohistochemical findings, the case was accepted as diffuse large B-cell lym- phoma, according to the Revised European-American Classification of Lymphoid Neoplasms (REAL). Nasophar- ynx, head and neck, thorax, and abdominal computed to- mographic scans were performed on the basis of the ob- served lymphoma morphology. No pathologic findings, such as lymphadenopathy, were detected in the axilla or any other site, except for increased density in the breasts. Results of endoscopic evaluation of the upper gastrointes- tinal system and nasopharynx were normal. Examination of peripheral blood samples and bone marrow aspiration and biopsy showed normal morphologic findings. The cri- teria needed to accept the case as PBL according to Wise- man and Liao 7 are (a) technically sufficient tissue, (b) close interaction between lymphoma infiltration and breast tis- sue, (c) no evidence of widespread disease at the time of diagnosis, and (d) no prior diagnosis of a nonbreast lym- phoma. Since the case complied with these criteria, it was accepted as PBL. Following the histologic diagnosis, 6 courses of CHOP (cyclophosphamide, hydroxydaunomycin, vincristine, and