Microglandular Adenosis margins positive for AMGA; however, the assessment of sur- gical margins in carcinomas remains controversial. S-100 stain- ing is helpful to obtain a tumor-free resection margin. The prognosis for MGACA varies [8,13], but most cases of carci- noma arising in MGA have a relatively favorable prognosis despite being ER and PR negative. Adjuvant chemotherapy is recommended for patients with axillary lymph node metasta- sis [2]. MGA, AMGA, and MGACA display similar pathological and immunohistochemical features, but their prognoses are much different. To mistake MGA for sclerosing adenosis or a tubular adenoma results in undertreatment, whereas misdiag- nosing MGA as MGACA results in overtreatment. Therefore, distinguishing MGA from AMGA or MGACA and appropri- ate management is very important. In conclusion, MGA of the breast is a very rare benign dis- ease that can mimic breast cancer clinically and pathologically. An MGA mass should be completely excised based on a core needle biopsy result because of its strong relationship with breast cancer. REFERENCES 1. McDivittRW, Stewart FW, Berg JW. Tumors of the breast. In: Armed Forces Institute of Pathology (U.S.), Universities Associated for Research and Education in Pathology. Atlas of Tumor Pathology, Second Serise, Fascicle 2. Wathington, D.C.: Armed Forces Institute of Pathology; 1968. p.91. 2. RosenPP. Rosen’s Breast Pathology. 3rd ed. Philadelphia: Wolters Kluw- er/Lippincott Williams & Wilkins; 2009. p.175-86. 3. RosenPP. Microglandular adenosis. A benign lesion simulating inva- sive mammary carcinoma. Am J Surg Pathol 1983;7:137-44. 4. GeyerFC, Kushner YB, Lambros MB, Natrajan R, Mackay A, Tamber N, 75 et al. Microglandular adenosis or microglandular adenoma? A molecu- lar genetic analysis of a case associated with atypia and invasive carcino- ma. Histopathology 2009;55:732-43. 5. EusebiV, Foschini MP, Betts CM, Gherardi G, Millis RR, Bussolati G, et al. Microglandular adenosis, apocrine adenosis, and tubular carcinoma of the breast. An immunohistochemical comparison. Am J Surg Pathol 1993;17:99-109. 6. PopperHH, Gallagher JV, Ralph G, Lenard PD, Tavassoli FA. Breast car- cinoma arising in microglandular adenosis: a tumor expressing S-100 immunoreactivity. Report of five cases. Breast J 1996;2:154-9. 7. TavassoliFA, Bratthauer GL. Immunohistochemical profile and differ- ential diagnosis of microglandular adenosis. Mod Pathol 1993;6:318-22. 8. JamesBA, Cranor ML, Rosen PP. Carcinoma of the breast arising in microglandular adenosis. Am J Clin Pathol 1993;100:507-13. 9. ShinSJ, Simpson PT, Da Silva L, Jayanthan J, Reid L, Lakhani SR, et al. Molecular evidence for progression of microglandular adenosis (MGA) to invasive carcinoma. Am J Surg Pathol 2009;33:496-504. 10. DiazNM, McDivitt RW, Wick MR. Microglandular adenosis of the breast. An immunohistochemical comparison with tubular carcinoma. Arch Pathol Lab Med 1991;115:578-82. 11. KoenigC, Dadmanesh F, Bratthauer GL, Tavassoli FA. Carcinoma aris- ing in microglandular adenosis: an immunohistochemical analysis of 20 intraepithelial and invasive neoplasms. Int J Surg Pathol 2000;8:303-15. 12. AcsG, Simpson JF, Bleiweiss IJ, Hugh J, Reynolds C, Olson S, et al. Mi- croglandular adenosis with transition into adenoid cystic carcinoma of the breast. Am J Surg Pathol 2003;27:1052-60. 13. KhalifehIM, Albarracin C, Diaz LK, Symmans FW, Edgerton ME, Hwang RF, et al. Clinical, histopathologic, and immunohistochemical features of microglandular adenosis and transition into in situ and inva- sive carcinoma. Am J Surg Pathol 2008;32:544-52. 14. ResetkovaE, Flanders DJ, Rosen PP. Ten-year follow-up of mammary carcinoma arising in microglandular adenosis treated with breast con- servation. Arch Pathol Lab Med 2003;127:77-80. 15. SalariehA, Sneige N. Breast carcinoma arising in microglandular ade- nosis: a review of the literature. Arch Pathol Lab Med 2007;131:1397-9. DOI: 10.4048/jbc.2011.14.1.72 http://ejbc.kr