Twenty-five cases of surgically proven urachal carcinomas were retrospectively reviewed. The radiological archives at the Armed Forces Institute of Pathology were searched for cases of surgically proven urachal carcinomas that had a computed tomographic (CT) scan as a part of their radiologic evaluation. CT images from all cases were evaluated to determine tumor morphology, presence and localization of calcification, extent of bladder invasion and metastases. Tumor size at presentation averaged 6cm. Twenty-one of 25 (84%) were mixed cystic solid lesions and 4/25 (16%) were completely solid. Calcifications were present in 18/25 (72%), with 11 peripherally located, 3 central only and 4 both. Bladder wall invasion was present in 23/25 (92%), but was seen as an intraluminal mass in only 13/25 (52%). The bulk of the mass was extravesicular in 22/25 (88%). Metastases were present in 12/25 (48%). Our series supports observations from other smaller series that a midline, calcified, supravesicular mass is highly suspicious, if not pathognomonic, for urachal carcinom

Thali-Schwab, Cornelia

Wagner, Brent

Woodward, Paula

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Received: 3 December 2003Revised: 11 May 2004Accepted: 4 June 2004Published online: 17 July 2004© Springer-Verlag 2004Abstract Twenty-five cases of sur-gically proven urachal carcinomaswere retrospectively reviewed. Theradiological archives at the ArmedForces Institute of Pathology weresearched for cases of surgicallyproven urachal carcinomas that had acomputed tomographic (CT) scan asa part of their radiologic evaluation.CT images from all cases were eval-uated to determine tumor morpholo-gy, presence and localization of cal-cification, extent of bladder invasionand metastases. Tumor size at pre-sentation averaged 6 cm. Twenty-one of 25 (84%) were mixed cysticsolid lesions and 4/25 (16%) werecompletely solid. Calcifications werepresent in 18/25 (72%), with 11 pe-ripherally located, 3 central only and4 both. Bladder wall invasion waspresent in 23/25 (92%), but was seenas an intraluminal mass in only13/25 (52%). The bulk of the masswas extravesicular in 22/25 (88%).Metastases were present in 12/25(48%). Our series supports observa-tions from other smaller series that amidline, calcified, supravesicularmass is highly suspicious, if not pa-thognomonic, for urachal carcinoma.Keywords Urachus · Urachal adenocarcinoma · Allantois · Computed tomography · Bladder development · Bladder neoplasmEur Radiol (2005) 15:79–84DOI 10.1007/s00330-004-2408-z U R O G E N I TA LCornelia M. Thali-SchwabPaula J. WoodwardBrent J. WagnerComputed tomographic appearance of urachaladenocarcinomas: review of 25 casesIntroductionThe urachus is a vestigial remnant of the intraembryonicportion of the allantois, which extends from the bladderdome to the umbilicus. Urachal carcinoma is a rare ma-lignant neoplasm comprising only 0.01% of all adultcancers [1]. They are even rare among bladder tumors,accounting for only 0.34% of all bladder neoplasms;however, up to 39% of bladder adenocarcinomas are ofurachal origin [2, 3]. Most adenocarcinomas of the ura-chus are mucinous. Less common histologic types in-clude transitional cell and squamous cell carcinoma.Several reviews have discussed the clinical aspects ofurachal carcinoma [3–5]. Because of the rarity of this tu-mor, the radiological literature consists primarily of casereports and small series [6–10]. In this paper, we de-scribe the computed tomographic (CT) findings in 25pathologically proven cases, which, to our knowledge, isthe largest series in the radiological literature.Materials and methodsThe radiological archives at the Armed Forces Institute of Pathol-ogy were searched for cases of surgically proven urachal carcino-This paper was in part presented at ECR2002. The opinions and assertions containedherein are the private views of the authorsand are not to be construed as official nor as representing the views of the Departmentof Defense of the United States.C. M. Thali-Schwab · P. J. WoodwardDepartment of Radiologic Pathology,Armed Forces Institute of Pathology,Washington, DC, USAB. J. WagnerReading Hospital,Reading, PA, USAC. M. Thali-Schwab (✉)Insel Hospital,University of Berne,3010 Berne, Switzerlande-mail: cornelia.thali@bluewin.chTel.: +41-31-6322111Fax: +41-31-6324874mas that had a CT scan as a part of their radiologic evaluation.These 25 cases were received between 1981 and 2001. The CTimages were evaluated to determine ] tumor morphology (cyst vs.solid) [1], presence [2] and localization [3] of calcification, extentof bladder invasion [4] and metastases [5]. The pathology and sur-gical reports were reviewed for all patients. The films were com-pared to the gross specimens and, where possible, clinical infor-mation regarding symptoms was obtained.ResultsThere were 13 males and 12 females with an average ageof 48 (range 21–69 years). Tumor size averaged 6 cm inthe largest cross-sectional diameter (range 2–12 cm).Twenty-one cases (84%) appeared as mixed cystic-solidlesions (16 predominantely cystic and 5 predominantelysolid); 4 (16%) were completely solid (Figs. 1, 2, 3). Allwere adenocarcinomas. The CT appearance correlatedwell with gross pathologic findings. Calcifications wereradiologically visible in 18/25 (72%) and varied fromfine punctate deposits to extensive areas of calcification.Eleven cases had purely peripheral calcifications, fourhad both peripheral and central calcification, and threeshowed purely central calcification (Figs. 4, 5, 6).Invasion of the bladder wall was very common and oc-curred in 23/25 (92%). Invasion, however, was not alwaysobvious by CT. In only 13/25 (52%) was there obvious in-vasion into the bladder lumen correlating with mucosal in-vasion by histology (Fig. 7). In 10/25 (40%), there was his-tologic invasion into the muscularis layer of the bladder,but the mucosa was preserved. The bladder wall did notappear abnormal in any of these cases. In 22 cases (88%),the extraluminal portion of the mass was larger than the in-traluminal portion. In the remaining two cases, the masswas totally extrinsic to the bladder without invasion.Sixteen of 25 (64%) had pathologically proven localperivesical fat invasion; in addition, two had lymphaticand two small bowel invasion (Fig. 8). Local invasion was80Fig. 1 a Axial and b sagittalreformatted CT images show a mixed cystic-solid lesion (arrows); B bladderFig. 2 a Axial CT imagedemonstrates a predominantlycystic lesion with a small solidcomponent (arrow). b Photo-graph of the resected tumor(arrow) and bladder (B)81Fig. 3 a Axial CT image of atotally solid lesion (arrows)with the b correspondingpathological specimenFig. 4 a Abdominal radiographand b corresponding axial CTimage shows a mass with pe-ripheral calcifications (arrows)Fig. 5 Axial CT image showing a single punctate central calcifi-cation within the mass (arrow)Fig. 6 Axial CT image with extensive peripheral and central tu-mor calcifications (arrows)suggested by CT when the borders of the mass were irreg-ular. Two cases of local invasion were not radiologicallyevident. At the time of initial diagnosis of the primary lesion, distant metastases were present in 8/25 (32%) andwere noted in the following locations: bone (2), cerebel-lum (1), peritoneal cavity (1), bilateral ovary (1), umbili-cal skin (1), perirectal soft tissues (1) and omentum (1).Clinical information was available in 22/25 patients.In our series 13/22 patients (59%) presented with hema-turia as the first clinical sign, 5/22 (23%) had pain (dif-fuse pain and dysuria 1, suprapubic pain on voiding 1,painful pelvic mass 1, dyspareunia 1, low back pain 1).Only 2/22 (9%) presented with mucinuria. One patient(5%) had no symptoms.82Fig. 7 Bladder invasion byurachal carcinoma. a Sagittalultrasound image shows a solidmass fungating into the bladderlumen (arrow). b Axial CT im-age shows this mass has bothcystic and solid components(arrows). c Photograph of theresected specimen shows a pre-dominately extraluminal mass(curved arrow) with involve-ment of the bladder mucosal(straight arrows). B bladderFig. 8 Urachal carcinoma withinvasion of the small bowel. a Abdominal radiograph afterinstillation of contrast into thebladder shows a vesicoentericfistula (arrow) with filling ofmultiple small bowel loops. b Axial CT image shows bothenteric contrast and gas withinthe tumorDiscussionThe intraembryonic portion of the allantois forms a con-nection from the apex of the bladder to the umbilicus. Asthe bladder enlarges, the allantois involutes and forms a fi-brous cord called the urachus or median umbilical ligament[10]. It is an extraperitoneal midline structure runningwithin the space of Retzius, between the transversalis fas-cia and the parietal peritoneum [1]. It can be quite variablein length (2–15 cm) and appearance (a well-defined liga-ment vs. a fine, fibrous plexus) [2]. Up to 30% of adultshave been shown to have a microscopic lumen at autopsy;however, functionally, the urachus is closed by the third tri-mester of fetal life [10]. Failure of complete urachal clo-sure gives rise to a variety of anomalies, including a patenturachus, urachal cyst, urachal sinus or a vesicourachal di-verticulum [10]. In addition to closure anomalies, benignand malignant neoplasms can arise in the urachus.Although the normal urachus is most commonly linedby transitional epithelium, the majority of urachal carci-nomas are adenocarcinomas [6]. Two theories have beensuggested as possible explanations. The first, and morecommonly accepted theory, proposes there is columnarmetaplasia of the transitional epithelium, which subse-quently undergoes malignant transformation [1, 3]. Analternative, although less likely, explanation is that ade-nocarcinomas could arise from embryonic rests withinislands of mucus-containing hindgut epithelium persist-ing within the urachus [7, 8].In our series, most tumors were complex, mixed, cys-tic and solid masses. The cystic portion was often filledwith mucinous material. A high mucin content con-tributes to the low-density appearance often seen on CT[2]. The minority (16%) were purely solid. In none of thecases was a purely cystic mass seen (a potential confu-sion for a urachal closure abnormality). As with mucino-us tumors elsewhere, urachal carcinoma has a propensityfor psammomatous calcification. Calcification is general-ly extensive enough that it is easily seen by CT. In our se-ries these calcifications occurred more often in the pe-riphery, but were also central or a combination of both.Histologically, urachal carcinoma is often indistin-guishable from a primary bladder adenocarcinoma. In allbut three of our cases, the bulk of the tumor was extralu-minal. This finding can be very helpful in differentiating itfrom a bladder adenocarcinoma, which would be expectedto be primarily intraluminal [9]. Bladder wall invasion iscommon in urachal carcinoma and was present in 92% ofcases in our series. This is not always an obvious CT find-ing, however. In 40% of the cases, invasion was confinedto the muscularis and was not apparent by CT. The area ofthe dome of the bladder is often difficult to evaluate sec-ondary to volume averaging effects. With newer multide-tector CT scanners, thinner sections and better multiplanarreformatting are possible and may improve the evaluationfor invasion. It is important to note that with conventionalaxial imaging, bladder wall invasion may be missed and anormal appearing bladder does not exclude invasion.The most common clinical symptoms described forurachal adenocarcinomas include hematuria, irritativebladder symptoms (frequency, urgency and dysuria) andpain. This was also true in our series. In a review seriesby Sheldon et al. [3], they reported mucinuria (either mi-croscopic or gross) in 25% of the patients. It was lowerin our series, occurring only in 2 of 22 patients (9%) forwhom history was available. This discrepancy may bedue to incomplete data. Three of our cases had no historylisted, and the other histories were written by the casecontributor, which may or may not have been complete.Our data varied further in that this series did not show asignificant male predilection, and the average age wasyounger than reported by others [2, 3].Because the tumor growth occurs in an area that isrelatively clinically silent, patients with urachal carcino-ma generally present late in their course, making theprognosis poor. They do far worse than patients with aprimary bladder adenocarcinoma, which is histologicallysimilar, but typically presents much earlier. In our series,28% had metastases at the time of presentation. Metas-tases have been reported most commonly to involve theregional lymph nodes, omentum, liver, lung and bone[2–5]. We found additional sites, including the cerebel-lum, peritoneal cavity, bilateral ovaries, umbilical skinand perirectal soft tissues.In conclusion, our series supports observations fromother smaller series that a midline, calcified, supravesic-ular mass is highly suspicious, if not pathognomonic, forurachal carcinoma. Bladder wall involvement is commonand cannot be excluded, even in the absence of radiolog-ical findings. In view of the high frequency of bladderinvasion at the time of presentation, the pathologist is of-ten unable to establish if the lesion is a primary tumor ofthe urachus or bladder by histologic examination alone.Therefore, based on the location of an extravesical com-ponent of the lesion, the radiologist may often be of value in suggesting that the neoplasm is urachal in origin.83References1. Hori S (1983) Staging of urinarybladder cancer—evaluation by CT.Nippon Igaku Hoshasen Gakkai Zasshi43:1024–10352. Brick SH, Friedman AC, Pollack HM,Fishman EK, Radecki PD, SiegelbaumMH, Mitchell DG, Lev-Toaff AS, Caroline DF (1988) Urachal carcinoma:CT findings. Radiology 169:377–3813. Sheldon CA, Clayman RV, Gonzalez R,Williams RD, Fraley EE (1984) Malig-nant urachal lesions. J Urol 131:1–84. Kakizoe T, Matsumoto K, Andoh M,Nishio Y, Kishi K (1983) Adenocarci-noma of urachus. Report of 7 cases andreview of literature. Urology21:360–3665. Mattelaer P, Wolff JM, Jung P, IJzerman W, Jakse G (1997) Adenocar-cinoma of the urachus: 3 case reportsand a review of the literature. ActaUrol Belg 65:63–676. Mangiacapra FJ, Scheraga JL, JonesLA (2001) Mucinous colloid adenocar-cinoma of the urachus. Radiographics21:965–9697. Mekras GD, Block NL, Carrion HM,Ishikoff M (1980) Urachal carcinoma:diagnosis by computerized axial tomo-graphy. J Urol 123:275–2778. Mostofi FK, Thomson RV, Dean AL(1954) Mucous adenocarcinomas of theurinary bladder. Cancer 8:7419. Narumi Y, Sato T, Kuriyama K, FujitaM, Saiki S, Kuroda M, Miki T, KotakeT (1988) Vesical dome tumors: signifi-cance of extravesical extension on CT.Radiology 169:383–38510. Yu JS, Kim KW, Lee HJ, Lee YJ, YoonCS, MJ Kim (2001) Urachal remnantdiseases: spectrum of CT and US find-ings. Radiographics 21:451–46184

Computed tomographic appearance of urachal adenocarcinomas: review of 25 cases

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Computed tomographic appearance of urachal adenocarcinomas: review of 25 cases

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