The medical literature was searched using PubMed for publications that reported a urachal adenocarcinoma concomitant with PM. The results of this survey are presented in Table 3.1 [7, 12, 19–28]. Mendeloff and McSwain recognized a direct relationship of mucinous PM and the urachal primary cancer [7]. Loggie et al. was the first to report a definitive treatment plan for the local-regional (LR) component of this disease [20]. In that patient, systemic metastases became evident at 20 months after diagnosis; the large-volume intraperitoneal component of the disease never recurred despite systemic progression of disease. Perioperative chemotherapy was used in the report by de Bree as well as in four of our five patients [12, 24]. The patient reported by de Bree et al. was alive and well at 9 years after treatment (personal communication).

In the patients reported in the medical literature and in our own five patients, the urachal mucinous neoplasm presented the clinical picture of pseudomyxoma peritonei. The diagnosis of urachal mucinous adenocarcinoma is rarely made prior to the initial exploratory surgery; often, the necessary plans to definitively treat the disease are not formed. However, in the patient presented above, prior experience with this disease led to a diagnosis preoperatively, and definitive treatment with CRS and HIPEC occurred as a single event. The symptom of mucus noted upon urination should be recognized as an unusual complaint distinctively associated with this rare disease. Computed tomography showing a cystic mass anatomically related to the position of the urachus can also suggest the diagnosis. In some patients, this primary tumor mass may be noted prior to the development and progression of the extensive mucinous ascites described as pseudomyxoma peritonei. In our patient and others shown in Table 3.1, a greatly elevated CA 19-9 tumor marker was helpful in making a diagnosis of mucinous urachal PM and has been utilized in follow-up.

In patients who present with mucosuria and a cystic lower midline abdominal mass on CT or magnetic resonance imaging (MRI), a primary urachal adenocarcinoma should be suspected. During the prolonged course of this disease prior to diagnosis, the urachal mucinous neoplastic cells gain access to the peritoneal cavity. In this environment, they continue to disseminate as neoplastic cells in mucinous ascites moving with peritoneal fluid throughout the peritoneal cavity. This characteristic pattern of tumor dissemination associated with pseudomyxoma peritonei is known as “redistribution phenomenon” [2, 29]. In some patients, the mucus from the primary tumor mass is also forced down a patent urachus into the bladder, causing mucosuria. A definitive treatment approach to this disease using CRS and HIPEC similar to that used for patients with pseudomyxoma peritonei from an appendiceal mucinous neoplasm may be of greatest benefit to these patients.

Complete excision of a primary urachal adenocarcinoma with clear margins is the treatment of choice if primary cancer resection alone can achieve negative margins. The mucinous nature of this neoplasm and the possibility for stray cancer cells developing at a later time as pseudomyxoma peritonei must be considered. An en bloc resection of dome of the bladder and tumor is the preferred surgical strategy. The decision to proceed with a cystectomy versus simple resection of the superior aspect of the bladder with negative margins will depend on the anatomic extent of the disease and its biological aggressiveness. In the proper clinical setting, cystectomy is not mandatory [30]. In patients with pseudomyxoma peritonei arising in a primary urachal adenocarcinoma, the disease is associated with a cystic primary cancer that produces copious mucus. In this type of primary cancer, deep invasion into the bladder is less likely to occur. In our patients and in the others reported in the literature, cystectomy was not required. Although the primary urachal cancer is usually manageable by surgical resection, the peritoneal spread presents a special problem in management requiring CRS and HIPEC.

Most of these patients have an elevated CEA and CA 19-9 tumor marker at the time of diagnosis of the pseudomyxoma peritonei (Table 3.1). In our patients, the tumor markers increased with disease recurrence and declined to normal with CCRS. These tumor markers should be used in a serial manner in follow-up. These mucinous tumors are well imaged by CT, especially if the bowel is filled by oral contrast. We recommend for follow-up tumor markers CEA and CA 19-9 every 3 months and chest, abdominal, and pelvic CT every 6 months for 5 years post-cytoreduction. Similar recommendations have been made for appendiceal malignancies [31].

Urachal remnants are usually lined by transitional-type epithelium; however, focal glandular metaplasia may give rise to mucinous adenocarcinoma similar to that seen with colon cancer. These tumors are similar to appendiceal neoplasms in that there is a large spectrum of biological aggressiveness between patients. In some patients, the epithelial cells are described as bland, well differentiated, and noninvasive and are thought to be of borderline malignancy [22]. In other reports, an aggressive signet ring histomorphology is reported [19]. We have suggested that the term “mucinous urachal neoplasms” be used to describe this clinical entity to include this broad range of histologic types of noninvasive- as well as invasive-appearing tumors.