Year : 2006 | Volume
: 22 | Issue : 4 | Page : 376--377
Villous adenoma of female urethra: An investigation of the mechanism of development regarding glandular neoplasms in the urinary tract
Masaki Shiota1, Noriaki Tokuda1, Takehiro Kanou1, Humio Yamasaki2,
1 Department of Urology, Saga Prefectural Hospital, Koseikan, Saga, Japan
2 Department of Pathology, Saga Prefectural Hospital, Koseikan, Saga, Japan
1-12-9, Mizugae, Saga, 840-0054
Villous adenomas are rare in the urinary tract. We herein report the fifth known such case while also making a review of the literature. A 54-year-old woman noticed a mass in her external genitalia and a tumor located on her external urethral orifice. The tumor was excised and pathologically confirmed to be a villous adenoma. Up to now, no sign of recurrence has been observed. However, we should be careful for malignant formation, because villous adenomas in the urinary tract frequently coexist with either adenocarcinoma or urothelial carcinoma.
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Shiota M, Tokuda N, Kanou T, Yamasaki H. Villous adenoma of female urethra: An investigation of the mechanism of development regarding glandular neoplasms in the urinary tract.Indian J Urol 2006;22:376-377
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Shiota M, Tokuda N, Kanou T, Yamasaki H. Villous adenoma of female urethra: An investigation of the mechanism of development regarding glandular neoplasms in the urinary tract. Indian J Urol [serial online] 2006 [cited 2020 Feb 23 ];22:376-377
Available from: http://www.indianjurol.com/text.asp?2006/22/4/376/29132
Although villous adenomas are common in the gastrointestinal tract, they are rare in the urinary tract. A few case series have so far been published, in addition to scattered individual case reports.,,,,,, We herein report a villous adenoma of the urethra in an elderly woman with a review of the literature.
A 54-year-old woman visited a local clinic in December 2005 because she noticed a mass in her external genitalia. In December 2005, she was transferred to our hospital. The mass was a soft, reddish and pedunculated tumor, measuring 5 x 3 cm in size and located in the external urethral orifice (6 o'clock direction) [Figure 1]. Cystoscopy revealed no tumor in either the proximal urethra or the urinary bladder. A tumor resection was performed at the base of the tumor under spinal anesthesia. The pathologic findings were a villous adenoma of the urethra without carcinoma. Immunohistochemical staining for Cytokeratin 7 (CK 7), Cytokeratin 20 (CK 20) and Ki 67 was performed using monoclonal antibody. Prominent positive immunohistochemical staining for CK 20 was thus identified. Immunohistochemical staining for CK 7 and Ki 67 revealed positive cells [Figure 2]. As of 10 months after resection, no signs of recurrence were observed and further follow-up is still going on.
Although villous adenomas are common neoplasms in the gastrointestinal tract, they are rare in the urinary tract. Only a few case series and some isolated case reports have been published. Cheng et al and Seibel et al reported 23 cases and 18 cases, respectively, of villous adenoma in the urinary tract. Villous adenomas have been reported in the entire urinary tract including the renal pelvis, ureter, urinary bladder,,,, urachus, and urethra.,, Although the urinary bladder is the most common site and 18 cases were reported in Cheng et al 's study, nevertheless, the female urethra remains a relatively rare site. In Cheng et al 's study, only two cases of villous adenoma originating from the female urethra have been reported. In Seibel et al 's study, no such cases occurring in the female urethra were reported. In addition, only two case reports have ever been published. Our case report is the fifth case of a villous adenoma occurring in the female urethra.
Histologically, villous adenomas in the urinary tract are similar to colonic villous adenomas. They exhibit rounded projections of a pseudostratified columnar epithelium with goblet-type mucin-producing cells. The immunohistochemical findings of villous adenomas arising in the urinary tract and gastrointestinal tract are also similar. CK 20 and carcinoembryonic antigen staining are positive, while epithelial membrane antigen staining is negative in most cases. However, in contrast to gastrointestinal lesions, CK 7 staining is positive in about 50% of cases of villous adenoma in the urinary tract. Our case is the first case that Ki 67 staining was performed for villous adenomas in the urinary tract. In our case, Ki 67 staining revealed partially positive. This means that villous adenomas in the urinary tract have partially high proliferative activity.
The precise mechanism by which glandular epithelial lesions arise in the urothelial-lined urinary tract is uncertain. One possible mechanism is that glandular neoplasms originate through a process of abnormal differentiation, whereby injured stems cells in the urothelium undergo glandular differentiation, thus resulting in glandular metaplasia and neoplasia. This theory is supported by the findings of Seibel et al. because the pathological variations suggest that these neoplasms arise in a precursor lesion with a broad potential for neoplasia along glandular, urothelial or sarcomatous pathways. Another possible mechanism is that cloacal remnants may remain in the adult bladder, urachus and urethra, with the potential to later give rise to glandular epithelial neoplasms. Embryologically, both the distal colorectum and bladder arise from the partitioning of the cloaca by the urorectal septum. We support this theory, because most of the villous adenomas previously reported in the urinary tract had a tendency to occur in the lower urinary tract such as the bladder, urachus and urethra. The occurrence at other sites, such as the kidney, renal pelvis and ureter is very rare, since only three cases (two in the ureter and one in the renal pelvis) have ever been reported. The difference in the occurrence rate between the upper urinary tract and the lower urinary tract suggests that glandular epithelial neoplasms rise from cloacal remnants. In this case, the tumor located in the lower urinary tract originated from the cloaca.
Although the mechanism of development regarding villous adenoma in the urinary tract is uncertain, the risk of malignant transformation has been suggested. In Cheng et al's study, eight of 23 cases were accompanied with adenocarcinoma. Seibel et al reported 12 of 18 cases with coexistent adenocarcinoma and/or urothelial carcinoma. Pure villous adenoma and well-sampled lesions containing in situ adenocarcinoma tend to indicate a favorable prognosis, even without any radical treatment. However, coexisting infiltrating carcinomas or urothelial carcinomas may lead to a more aggressive course. Therefore, an exact pathological evaluation of specimens for malignancy and a long-term follow-up are required.
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