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Benign urachal remnants can be encountered in the adult urinary bladder and it is recognized that these can uncommonly give rise to urachal urothelial carcinoma. However, urachal remnants containing urothelial carcinoma incidentally encountered in cystectomies for bladder cancer has not been previously described. Herein, we present 8 adult bladder cancer cystectomies with incidental urachal remnants containing urothelial carcinoma. All 8 incidental urachal remnants with tumor were located at the dome that varied from small tubular to tubulocystic structures and contained urothelial carcinoma in situ (CIS) (6), noninvasive high-grade papillary urothelial carcinoma (PUC) (1), and coexistent noninvasive high-grade PUC and urothelial CIS (1). Six of the 8 urachal remnants with tumor also showed benign urothelial cells (2), mixed urothelial and glandular cells (2), and cuboidal cells (2). The bladder mucosa directly above the remnant showed urothelial CIS (4), PUC (1), concomitant PUC and urothelial CIS (1), invasive urothelial carcinoma (1), and benign urothelium (1); only 1 remnant intermingled with invasive urothelial carcinoma nests. Two remnants with tumor were at a region away from the main bladder tumor including the one overlaid by benign urothelium. The remnant with tumor extended into the upper half (5) or lower half (3) of muscularis propria (MP) and if misinterpreted as MP invasion, 5 of 8 bladder tumors will be overstaged. In conclusion, urachal remnant can have an early involvement by urothelial CIS or PUC similar in the bladder proper lumen. Urothelial carcinoma involving the urachus can be divided into a: (a) contiguous spread from a bladder urothelial carcinoma, (b) separate (noncontiguous) focus concomitant to bladder urothelial carcinoma, and (c) primary urachal urothelial carcinoma. Caution is warranted not to over interpret urachal remnant involvement by noninvasive urothelial carcinoma as an invasive tumor focus which could lead to overstaging.

Published experience remains limited for glandular neoplasms of the urachus, especially mucinous cystic tumors. We reviewed 55 glandular urachal neoplasms to evaluate their clinical features and histopathologic spectrum and to devise a classification system for the mucinous cystic forms. Within the 55 cases studied, we observed 2 groups with differing clinical, gross, and histopathologic features. The first group, invasive, noncystic adenocarcinomas (n=24), had clinicopathologic features in accord with the known spectrum of urachal adenocarcinoma (mean age 50 y, female:male ratio 1.7, with recurrence or death from disease in 9/16 cases over a 45 mo mean follow-up). The second group, mucinous cystic tumors (n=31), morphologically resembled mucinous cystic tumors of the ovary and appeared classifiable by the same approach (mean age 47 y, female:male ratio 1.4) and included mucinous cystadenoma (n=4), mucinous cystic tumor of low malignant potential (n=22, including 2 cases with intraepithelial carcinoma), and mucinous cystadenocarcinoma with microscopic (n=4) or frank invasion (n=1). Follow-up information was available for 13 patients with mucinous cystic tumors (mean 41 mo); we observed no local recurrence or distant metastasis. This experience suggests that there is a distinct group of glandular, cystic tumors of the urachus that is classifiable in a manner similar to ovarian neoplasms and that has a favorable prognosis after complete excision. As with cystic neoplasms of other organs, rigorous sampling is recommended to identify potentially small foci of carcinoma that could be missed by inadequate sampling. Accordingly, classification based on methods other than complete surgical excision may be hazardous.

Background: Urachal carcinomas occur mostly in the bladder dome, comprising 22% to 35% of vesical adenocarcinomas, and are generally treated by partial cystectomy with en bloc resection of the median umbilical ligament and umbilicus. Detailed pathologic studies with clinical outcome correlation are few., Design: We reviewed histologic material and clinical data from 24 cases selected from a database of 67 dome-based tumors diagnosed and treated at our institution from 1984 to 2005. Follow-up information was available for all 24 patients., Result: The mean age at diagnosis was 52 years (range: 26 to 68 y). Fifteen patients were male and 9 were female. Location was the dome in 23 and dome and anterior wall in 1. Thirteen cases were pure adenocarcinoma, not otherwise specified, 9 were enteric type adenocarcinoma, and 2 were adenocarcinoma with focal components of lymphoepithelioma-like carcinoma and urothelial carcinoma with cytoplasmic clearing. Signet ring cell features were focally seen in 2 cases. Cystitis cystica and cystitis glandularis were seen in 4 and 2 cases, respectively. In all instances but 1, cystitis cystica/glandularis was focal and predominantly in the bladder overlying the urachal neoplasm. Urachal remnants were identified in 15 cases: the urachal epithelium was benign urothelial-type in 6 cases and showed adenomatous changes in 9. The overlying bladder urothelium was colonized by adenocarcinoma in 3 cases. In all 3, urachal remnants were identified and showed transition from benign to adenomatous epithelium. On immunohistochemistry, these tumors were positive for CK20 and variably positive for CK7 and 34BE12. The majority showed a cytoplasmic membranous staining pattern for beta-catenin, although in 1 case, focal nuclear immunoreactivity was identified. The Sheldon pathologic stage was pT1 in 0, pT2 in 2, pT3a in 8, pT3b in 11, pT3c in 1, pT4a in 1, and pT4b in 1 patient. One patient had a positive soft tissue margin. The mean follow-up period was 40 months (range: 0.3 to 157.6 mo). Seven of 24 (29%) cases recurred locally. The incidence of local recurrence was higher in patients who underwent a partial cystectomy alone (37.5%) versus those who had a more radical surgery (27%). Distant metastases occurred in 9 (37.5%) patients, 4 of whom had no prior local recurrence. Seven patients (29%) died of the disease. All cases with locally recurrent and metastatic disease belonged to stage pT3 or higher., Conclusions: Pathologic stage is an important prognostic factor in urachal carcinoma. Surface urothelial involvement by carcinoma and presence of cystitis cystica/glandularis do not necessarily exclude the diagnosis of urachal carcinoma. Immunostains do not unequivocally discriminate a urachal from a colorectal carcinoma, but diffuse positivity for 34BE12 would support, and diffuse nuclear immunoreactivity for beta-catenin would militate against, a diagnosis of urachal carcinoma. Local recurrence may be owing to seeding within the distal urothelial tract, particularly in tumors with a configuration that is polypoid and which open into the bladder cavity. The type of surgery performed may have an effect on local recurrence despite negative margins of resection.