Case Study by J . Corbin Norton ; Nickolas D . Scherzer , MD ; Jeffrey T . Alliston , MD ; Dennis W . Jacks , MD ; Douglas E . Claybrook , MD ; David A . Lupo , MD
Department of Urology , UAMS , Little Rock , Ark .
Villous Adenoma of the Prostatic Urethra : A Rare Tumor in a Rare Location
Introduction While villous adenomas of the gastrointestinal tract are common place , their location within the urinary tract is exceedingly rare . To date , only a handful of case series and reports have been published . In addition , most reported cases involve either the urinary bladder or urachus , while villous adenoma of the urethra is even less common . As these lesions ’ malignant potential is still not fully understood , we present an additional case of villous adenoma of the prostatic urethra to draw further attention to this scarcely seen lesion .
Case Report The patient that this report will describe is a 75-year-old caucasian male who presented with obstructive lower urinary tract symptoms that had progressively worsened over the course of a year . Urinalysis was negative for hematuria and positive for bacteria , white blood cells , and leukocyte esterase . He was being treated for a urinary tract infection with macrolide antibiotics . He was initially seen a few months earlier for similar symptoms . Cystoscopy at that time showed a papillary tumor in the prostatic urethra at the level of the verumontanum , with an exudative film extending to the bladder neck . Repeat cystoscopy revealed a papillary lesion that occluded the entire prostatic urethra . The patient underwent a transurethral resection of the prostatic urethral tumor extending from the bladder neck to the verumontanum , resulting in an open channel . Direct visualization of the bladder did not reveal any other co-pathologies . The prostatic curettings were evacuated and sent for pathology . Specimens consisted of tan-pink soft tissue measuring 9.5cm x 6.8cm in aggregate . Microscopic examination was consistent for villous adenoma with no evidence of high-grade dysplasia or invasive carcinoma . CT of the chest , abdomen , and pelvis following the procedure showed no evidence of malignancy or metastatic disease . The patient was diagnosed with villous adenoma of the prostatic urethra . At clinical follow-up , patient reports no complications and improved lower urinary tract symptoms . He will be followed with a cystoscopy three months postoperatively to monitor for recurrence .
Discussion Villous adenomas are benign glandular neoplasms more commonly seen in the gastrointestinal tract . While rare , they can also occur anywhere along the urinary tract , with cases most commonly reported in the bladder , followed by the urachus , urethra , and ureter . 1-3 This case illustrates a 75-year-old white male with a villous adenoma of the prostatic urethra . This is a rare location with isolated reported cases and two case series reported within the literature . Since 1981 , there have only been two other cases of villous adenoma of the urinary tract at our institution , with neither being recent enough for records to review .
Villous adenomas are more commonly found in men who range in ages from 53 to 93 , with an average age of 69.6 years 2 . Patients typically present with hematuria , irritative voiding symptoms and sometimes mucosuria 1 , 2 Our patient did not present with hematuria but instead had obstructive urinary tract symptoms with urgency , increased frequency , and difficulty voiding .
There is still debate regarding the exact pathogenesis of villous adenomas within the urinary tract , but generally there are two proposed mechanisms . The first discussed by Atik et al ., describes the shared embryologic origin of the rectum and urinary bladder . They both are derived from the cloaca , which is an endoderm lined portion of the terminal hindgut . During embryogenesis , the urorectal septum divides the cloaca dorsally into the rectum and anal canal , and ventrally into the bladder and urogenital tract . A potential defect in this process may occur , leaving behind cloacal remnants that could later develop into a glandular epithelial neoplasm 4 . The second proposed mechanism suggests a chronic irritation-metaplasia-dysplasia-carcinoma sequence . Irritation in the form of infection , chemical injury , or calculi can damage urothelial stem cells resulting in glandular metaplasia 5 . This theory is supported by the presence of neutral mucins , acidic sulphomucins , and sialomucins within the villous adenomas and in cystitis glandularis 6 as well as similar genetic compositions between villous adenoma and dysplastic regions of flat metaplastic mucosa . 5 .
Villous adenomas of the urinary tract share the same histologic features as their colonic counterparts . They are characterized by papillary projections lined by pseudostratified columnar epithelium with mucin-producing goblet cells . Epithelial cells often display nuclear atypia and mild dysplastic changes . 3 Unsurprisingly , immunohistochemistry between villous adenomas of the colon and urinary tract share similarities in that they are strongly positive for cytokeratin 20 ( CK20 ) and carcinoembryonic antigen ( CEA ) and are most often negative for epithelial membrane antigen ( EMA ). 1 , 3 , 4 , 7 Cytokeratin 7 ( CK7 ) is positive in 50 % -56 % of villous adenomas of the urinary tract , which helps differentiate it from intestinal villous ade-
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