Journal of Breast Cancer C A S E R E P O R T Microglandular Adenosis J Breast Cancer 2011 March; 14(1): 72-75 DOI: 10.4048/jbc.2011.14.1.72 Dong-Ju Kim, Woo-Young Sun, Dong-Hee Ryu, Jin-Woo Park, Hyo-Young Yun, Jae-Woon Choi, Young-Jin Song Department of Surgery, Chungbuk National University, College of Medicine and Medical Research Institute, Cheongju, Korea Microglandular adenosis (MGA) of the breast is a very rare and benign proliferative lesion. Most patients complain of a palpable breast mass that may arouse a clinical suspicion of breast can- cer. Histopathologically, it is hard to distinguish MGA from breast cancer because of the lack of a myoepithelial layer and infiltra- tive proliferation. Several studies have reported a strong relation- ship between MGA and carcinoma arising in MGA, so the mass should be excised completely in cases of MGA determined from a core needle biopsy rather than observation. A 72-years-old woman presented with a palpable breast mass. On physical ex- amination, a mass was palpable in the right upper outer quadrant area and somewhat fixed to the surrounding tissues and pectora- lis major muscle. We could not detect any mass or dense lesion on mammography because of a grade 4 dense breast. Ultraso- nographic findings revealed a low echoic lesion with indistinct margins. The result of a core needle biopsy was MGA, which was confirmed by excision. We report one case of MGA, which was believed to breast cancer clinically. Key Words: Breast, Cancer, Microglandular adenosis INTRODUCTION Microglandular adenosis (MGA) is a very rare disease and has not been reported in Korea. MGA often produces a pal- pable mass that mimics breast cancer on breast examination. Histologically, small round glands lacking a myoepithelial lay- er infiltrates normal stroma making it difficult to distinguish MGA from well-differentiated breast cancer. Despite its char- acteristic infiltrative growth pattern, aggressive local spread or metastasis has not been reported, so it is recognized as a benign lesion. Until now, the treatment choice for MGA is observa- tion, because MGA is known as a benign disease but more re- cent data show that MGA is highly related to cancer. For that reason, a reassessment of the treatment plan is required for cases in which a core needle biopsy reveals MGA. CASE REPORT A 72-years-old woman presented with a palpable breast mass. Correspondence: Young-Jin Song Department of Surgery, Chungbuk National University College of Medicine and Medical Research Institute, 410 Seongbong-ro, Heungdeok-gu, Cheongju 361-763, Korea Tel: +82-43-269-6361, Fax: +82-43-266-6037 E-mail: yjsong@chungbuk.ac.kr This work was supported by the research grant of the Chungbuk National University in 2009. Received: September 8, 2010 Accepted: December 9, 2010 © 2011 Korean Breast Cancer Society On physical examination, about 2 cm of the mass was palpa- ble at 11 o’clock and 2 cm from the right breast nipple. The mass was somewhat fixed to the surrounding tissues and the pectoralis major muscle. No nipple discharge, dimpling, or skin changes were noted. The mammographic finding was a grade 4 dense breast with benign calcifications in both breasts. A 1.2 cm ill-defined low echoic lesion (BIRADS category 5) was shown in the upper outer quadrant of the right breast on an ultrasonogram (Figure 1). We performed a core needle bi- opsy to rule out breast cancer. The result of the core needle bi- opsy was MGA, so we excised the mass completely. The excised mass was about 3 × 2 cm and 1.2 × 1 cm of the main mass was shown. The lesion was firm, nodular, and had irregular mar- gins (Figure 2). Microscopic findings revealed many small glands infiltrating the fibrous stroma. The glands were regular, small, and lined by a single epithelial cell layer (Figure 3). Im- munohistochemical staining was positive for S-100 protein (Figure 4), and the epithelial cells were negative for estrogen receptor. No evidence of recurrence during a breast examina- tion and ultrasonogram was found at the 6-month follow-up. DISCUSSION MGA of the breast is known as a benign proliferative glan- dular lesion and was first described in 1968 by McDivitt et al. [1]. MGA can mimic well differentiated breast cancer both clini- cally and pathologically [2]. All reported patients with MGA http://ejbc.kr | pISSN 1738-6756 eISSN 2092-9900