500 confined for a long time without local invasion or distant metastases [8]. Unfortunately, it is not easy to distinguish urachal adenocarcinoma from other origins of adeno- carcinoma, but distinction between them is important in determining an appropriate therapy and assessing prog- nosis. Although the normal urachus is most commonly lined by transitional epithelium, urachal carcinomas pre- dominantly manifest as adenocarcinomas, which are lined by mucus-secreting epithelial cells resembling those of the colorectum, probably due to metaplasia of the urachal mu- cosa into columnar epithelium followed by malignant transformation [9]. Therefore, a biologic marker for con- firming the origin of the urachal adenocarcinoma is needed. 　Several studies have differentiated among bladder, ura- chal, and metastatic adenocarcinoma. Torenbeek et al showed that CEA, PSA, OC125, and vimentin can be help- ful in differentiating primary adenocarcinomas of the uri- nary bladder from secondary involvement by adeno- carcinomas originating from surrounding organs [2]. CEA was expressed in all urachal adenocarcinomas, 96% of co- lonic adenocarcinomas, and only 29% of the bladder neo- plasms. The results of CEA expression in urachal and co- lonic carcinomas may represent the fact that the embryo- logic origin of the urachus and colon is the same [1]. Cyto- keratin 7 expression was expressed in 82% of adeno- carcinomas of the bladder, and focally in 40% of urachal and 38% of colonic adenocarcinomas. Cytokeratin 20 was ex- pressed in more than 80% of all kinds of adenocarcinomas; therefore, cytokeratin 20 expression was not organ specific [2]. Suh et al. revealed that lack of CDX24 and villin signals strongly pointed to a primary bladder adenocarcinoma and AMACR is typically negative or weakly positive in ur- othelial carcinoma [3]. In this case, the result of immuno- histochemistry of the tumor was not conclusive in demon- strating urachal adenocarcinoma. However, there was no clinical evidence of secondary involvement of adeno- carcinoma from the bladder or colorectum. 　AMACR is globally used as a reliable marker for prostate adenocarcinoma, but expression has also been demon- strated in various other neoplasms [4-6]. No AMACR ex- pression in a urachal tumor has been reported. In our case, the tumor cells expressed AMACR, but were PSA negative by immunohistochemistry. Moreover, there was no clinical Ha et al evidence of prostate adenocarcinoma. The expression of AMACR in this case may be aberrant, but could be a specific tumor marker for urachal adenocarcinoma. Thus, as far as we aware, this is the first report of urachal adenocarcinoma originating from the abdominal wall with expression of AMACR. Further examinations would be needed to clarify if AMACR expression is specific for urachal adenocarcinoma. Conflicts of Interest The authors have nothing to disclose. REFERENCES 1. Sheldon CA, Clayman RV, Gonzalez R, Williams RD, Fraley EE. Malignant urachal lesions. J Urol 1984;131:1-8. 2. Torenbeek R, Lagendijk JH, Van Diest PJ, Bril H, van de Molengraft FJ, Meijer CJ. Value of a panel of antibodies to identify the primary origin of adenocarcinomas presenting as bladder carcinoma. Histopathology 1998;32:20-7. 3. Suh N, Yang XJ, Tretiakova MS, Humphrey PA, Wang HL. Value of CDX2, villin, and alpha-methylacyl coenzyme A racemase im- munostains in the distinction between primary adenocarcinoma of the bladder and secondary colorectal adenocarcinoma. Mod Pathol 2005;18:1217-22. 4. Leav I, McNeal JE, Ho SM, Jiang Z. Alpha-methylacyl-CoA race- mase (P504S) expression in evolving carcinomas within benign prostatic hyperplasia and in cancers of the transition zone. Hum Pathol 2003;34:228-33. 5. Xu J, Stolk JA, Zhang X, Silva SJ, Houghton RL, Matsumura M, et al. Identification of differentially expressed genes in human prostate cancer using subtraction and microarray. Cancer Res 2000;60:1677-82. 6. Daugherty SE, Platz EA, Shugart YY, Fallin MD, Isaacs WB, Chatterjee N, et al. Variants in the alpha-Methylacyl-CoA race- mase gene and the association with advanced distal colorectal adenoma. Cancer Epidemiol Biomarkers Prev 2007;16:1536-42. 7. Yu JS, Kim KW, Lee HJ, Lee YJ, Yoon CS, Kim MJ. Urachal rem- nant diseases: spectrum of CT and US findings. Radiographics 2001;21:451-61. 8. Dandekar NP, Dalal AV, Tongaonkar HB, Kamat MR. Adenocarcinoma of bladder. Eur J Surg Oncol 1997;23:157-60. 9. Eble JN, Hull MT, Rowland RG, Hostetter M. Villous adenoma of the urachus with mucusuria: a light and electron microscopic study. J Urol 1986;135:1240-4. Korean J Urol 2010;51:498-500