prognosis. Recently, it has been reported that the prog- nosis depends on the stage at the time of diagnosis and that low-stage small cell carcinomas respond to conven- tional treatment without progression of the disease [9]. In summary, the primary small cell carcinoma of the breast in our patient presented with imaging findings sim- ilar to the usual type of ductal carcinoma in early and ad- vanced stages. Although the period of tumor progression depends on variable factors, our case could serve as a val- uable example to assess the biology of this tumor. Immu- nohistochemistry may help to differentiate this rare breast malignancy from the other tumors which have similar gross and microscopic features. CONFLICTS OF INTEREST No potential conflict of interest relevant to this article was reported. REFERENCES 1. Sapino A, Bussolati G. Is detection of endocrine cells in Small cell carcinoma of the breast breast adenocarcinoma of diagnostic and clinical sig- nificance? Histopathology 2002;40:211-4. 2. Modlin IM, Oberg K, Chung DC, Jensen RT, de Herder WW, Thakker RV, et al. Gastroenteropancreatic neuro- endocrine tumours. Lancet Oncol 2008;9:61-72. 3. Wade PM Jr, Mills SE, Read M, Cloud W, Lambert MJ 3rd, Smith RE. Small cell neuroendocrine (oat cell) carcinoma of the breast. Cancer 1983;52:121-5. 4. Shin SJ, DeLellis RA, Ying L, Rosen PP. Small cell carcino- ma of the breast: a clinicopathologic and immunohisto- chemical study of nine patients. Am J Surg Pathol 2000; 24:1231-8. 5. Rosen PP. Mammary carcinoma with endocrine features. In: Rosen PP, editor. Rosen's breast pathology. 2nd ed. Phi- ladelphia: Lippincott Williams & Wilkins; 2001. p. 503-8. 6. Papotti M, Gherardi G, Eusebi V, Pagani A, Bussolati G. Primary oat cell (neuroendocrine) carcinoma of the breast. Report of four cases. Virchows Arch A Pathol Anat Histopathol 1992;420:103-8. 7. Kinoshita S, Hirano A, Komine K, Kobayashi S, Kyoda S, Takeyama H, et al. Primary small-cell neuroendocrine car- cinoma of the breast: report of a case. Surg Today 2008; 38:734-8. 8. Shin SJ, DeLellis RA, Rosen PP. Small cell carcinoma of the breast--additional immunohistochemical studies. Am J Surg Pathol 2001;25:831-2. 9. Kitakata H, Yasumoto K, Sudo Y, Minato H, Takahashi Y. A case of primary small cell carcinoma of the breast. Breast Cancer 2007;14:414-9. 10. Mariscal A, Balliu E, Díaz R, Casas JD, Gallart AM. Primary oat cell carcinoma of the breast: imaging features. AJR Am J Roentgenol 2004;183:1169-71. thesurgery.or.kr 119