Michael O. Koch, MD, FACS
Andrew D. Strine, MD
BASICS
DESCRIPTION
• Urachal carcinoma is a rare non-urothelial malignancy (almost always adenocarcinoma) usually involving the dome of the bladder due to direct extension from the urachal ligament, the structure from which this tumor arises.
• Rare malignancy
– Less than 1% of all bladder cancers
• Almost exclusively occurs in adults and most commonly in the 4th to 5th decades.
• Adenocarcinoma is the most common histologic subtype.
• Staging is distinct from bladder cancer but not standardized.
– Sheldon, Mayo (1,2), and Ontario (3) staging systems
• Generally has a poor prognosis due to delayed diagnosis but may be curable with early surgical resection.
EPIDEMIOLOGY
Incidence
1 in 5 million cases annually
Prevalence
Unknown due to its rarity and often asymptomatic nature
RISK FACTORS
None
Genetics
None
PATHOPHYSIOLOGY
• Originates from the urachus.
– Serves as a communication between the developing bladder and allantois but becomes a fibrous band by 12 weeks of gestation and is recognized as the median umbilical ligament in adults.
– Composed of urothelium-lined lumen of epithelial origin as well as submucosa and smooth muscle of mesenchymal origin.
Any layer may undergo a malignant transformation.
• Locally invades into muscularis propria and perivesical fat with demarcation from urothelium.
• Local extends to space of Retzius, anterior abdominal wall, umbilicus, and peritoneal cavity.
• Metastasizes to pelvic lymph nodes, lungs, liver, and bone.
ASSOCIATED CONDITIONS
Urachal remnants, including patent urachus, urachal sinus, cyst, and diverticulum
GENERAL PREVENTION
None
DIAGNOSIS
HISTORY
• Increasing incidental detection due to routine use of imaging
• Often asymptomatic until more advanced
• Presenting signs and symptoms
– Hematuria (most common) or mucosuria
– Abdominal pain
– Voiding symptoms or urinary tract infection (UTI)
– Umbilical drainage
– Omphalitis
– Umbilical mass
PHYSICAL EXAM
• Palpable urachal mass
– Large, fixed mass or concurrent ascites may suggest locally advanced, unresectable disease.
• Umbilical drainage or mass that fluctuates in size is more consistent with an infected urachal sinus or cyst.
• Perform a pelvic and rectal examination to evaluate for a gynecologic or rectal malignancy.
• Evaluate for any systemic signs and symptoms of infection and metastatic disease.
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• Hematologic and chemistry panels
• Urinalysis and urine culture to evaluate for microscopic hematuria and UTI
• Urine cytology to evaluate for a urothelial malignancy
• CA-125 and CA 19-9
– May be elevated in 40–60% of patients
– Useful in evaluating the response to systemic therapies
Imaging
• Abdominal ultrasound
– Often obtained during the initial evaluation and in the pediatric population
– High specificity for urachal cysts
– Significant false-positive rate for other urachal lesions
– Poor characterization of locally advanced disease
• CT or MRI of the abdomen and pelvis with IV and PO contrast
– Gold standard for diagnosis and staging
– Midline, calcified, partially cystic mass with local extension is concerning for but not diagnostic of urachal carcinoma.
• Chest x-ray or CT of chest for staging
• Bone scan if advanced disease, bony symptoms, or elevated alkaline phosphatase
Diagnostic Procedures/Surgery
• Cystoscopy with transurethral biopsy or resection
– Evaluate for intravesical invasion, drop metastases, or metasynchronous bladder cancer
– Biopsy or resection of tumor and adjacent normal urothelium is recommended but may be difficult due its extravesical location.
– Any tumor arising from the dome of bladder should be considered urachal in origin until proven otherwise.
• Percutaneous biopsy may be performed but raises a theoretical concern for seeding the biopsy tract.
Pathologic Findings
• A majority (>80%) is adenocarcinoma with glandular features and produces mucin.
– Similar immunohistochemistry to colonic adenocarcinoma (1)
Strong reactivity for 34BE12 and lack of diffuse nuclear reactivity for β-catenin is more suggestive of urachal origin.
– No immunohistochemical markers to differentiate adenocarcinoma originating from the urachus and bladder
• Other subtypes
– Sarcoma
– Squamous-cell carcinoma
– Urothelial carcinoma
• Pathologic criteria
– Definitive
Tumor located in the dome of bladder or along midline
Demarcation between tumor and urothelium
– Supportive
Presence of urachal remnant in tumor
Enteric-type pathology
Absence of urothelial dysplasia or carcinoma
Absence of cystitis glandularis and cystisa
• Favorable (well-differentiated) histology may have a better prognosis than unfavorable (poorly differentiated) histology for similarly staged tumors (3).
DIFFERENTIAL DIAGNOSIS
• Primary bladder lesion
– Primary bladder cancer of any histologic type at the dome of bladder
– Secondary malignancy of gynecologic or colorectal origin invading into the bladder
• Periumbilical mass
– Urachal remnants
Patent urachus
Urachal cyst
Urachal sinus
Vesicourachal diverticulum
– Umbilical hernia
– Urachal neoplasms: Adults
Benign (very rare): Adenomas, fibromas, fibroadenomas, fibromyomas, hamartomas
Malignant (very rare, less than 0.5% of all bladder cancers): Mostly adenocarcinoma
– Sister Mary Joseph nodule (adults): Umbilical metastasis of primary tumors (if primary is known, usually from genital or GI tract)
– Others: Dermoid cyst, sebum cyst, spontaneous umbilical fistula from Crohn disease/TB/perforated appendix, and skin cancers such as basal-cell or squamous-cell carcinoma
TREATMENT
GENERAL MEASURES
• Typically manifests as locally advanced or metastatic disease.
– Less than 20% of patients present with stage 1 (no invasion) or 2 (invasion confined to urachus) disease based on Sheldon staging system in most series.
• Management is controversial but typically involves surgical resection.
• Chemotherapy and radiation therapy are generally thought to be less effective and reserved for higher stage disease.
MEDICATION
First Line
• Chemotherapy is typically reserved for unresectable or metastatic disease.
– No standard regimen established.
– Regimens using 5-fluorouracil, cisplatin, and either α-interferon or gemcitabine and lucovorin are superior to others.
– Median overall survival of 20 months reported in patients with at least a partial response or stabilized disease (4)[B].
• No definitive role for neoadjuvant chemotherapy
Second Line
No definitive role but often used as an adjuvant therapy for margin- and node-positive disease as well as recurrences.
SURGERY/OTHER PROCEDURES
• Radical cystectomy or partial cystectomy with wide surgical margins and en-bloc resection of urachal remnant extending from bladder to umbilicus, posterior rectus sheath, and all tissue between medial umbilical ligaments is recommended for lower stage, resectable disease.
– Partial cystectomy may offer a comparable oncologic outcome and less morbidity to radical cystectomy if tumor is completely resected (3 – 5)[C].
– Failure to resect the umbilicus and positive surgical margins are associated with a worse outcome (2,4,5)[B].
• Bilateral pelvic lymph node dissection
– Should follow the standard template for bladder cancer.
– May be useful for staging but does not provide any survival advantage (1,2)[B].
• Surgical resection is particularly well suited to a laparoscopic or robotic approach with comparable short-term outcomes.
ADDITIONAL TREATMENT
Radiation Therapy
• Limited evidence
• Occasionally used for unresectable or metastatic disease (with chemotherapy) or as an adjuvant therapy for margin- and node-positive disease as well as recurrences.
• Median overall survival of 19.5 mo and 21 mo reported after radiation therapy alone and radiation therapy with chemotherapy, respectively (1)[B].
Additional Therapies
None
Complementary & Alternative Therapies
None
ONGOING CARE
PROGNOSIS
• Clinical and pathologic staging is the most important predictor of survival (1 – 5)[B].
– Two staging systems (Sheldon and Ashley) (6) (See Section II: Urachal Carcinoma Staging Systems)
• 5-yr overall survival rates range from 27 to 80%, depending on the series.
– About 50% for locally advanced disease (1 – 5)[B]
– Less than 20% for metastatic disease (1 – 4)[B]
– 93% for disease confined to the urachus and bladder after surgical resection with bladder preservation (5)[B]
– 69% for extravesical and peri-urachal disease after surgical resection with bladder preservation (5)[B]
COMPLICATIONS
• Bleeding
• Infection
• Injury to surrounding organs
• Urinary leak
• Lymphocele
• Postoperative cardiopulmonary complications, including myocardial infarction, deep vein thrombosis, and pulmonary embolism
• Development of recurrent or progressive disease
FOLLOW-UP
Patient Monitoring
• No standard schedule for oncologic surveillance established
• Adaptation from bladder cancer
– Radical cystectomy
History and physical examination, electrolytes, serum creatinine, and urine cytology every 3–6 mo for 2 yr and then as clinically indicated
Imaging of the chest, abdomen, and pelvis every 3–12 mo for 2 yr based on risk of recurrence and then as clinically indicated
– Partial cystectomy
Same as above
Cystoscopy every 3–6 mo for 2 yr and then at increasing intervals as clinically indicated
Patient Resources
• Bladder Cancer, National Cancer Institute, National Institutes of Health
– www.cancer.gov/cancertopics/types/bladder
• Urachal cancer, Offices of Rare Diseases Research, National Institutes of Health
– rarediseases.info.nih.gov/gard/7836/urachal-cancer/resources/1
• Urachal Anomalies, Urology Care Foundation, American Urologic Association
– www.urologyhealth.org/urology/index.cfm?index=41
REFERENCES
1. Molina JR, Quevedo JF, Furth AF, et al. Predictors of survival from urachal cancer: A Mayo Clinic study of 49 patients. Cancer. 2007;110(11):2434–2440.
2. Ashley RA, Inman BA, Sebo TJ, et al. Urachal carcinoma: Clinicopathologic features and long-term outcomes of an aggressive malignancy. Cancer. 2006;107(40):712–720.
3. Pinthus JH, Haddad R, Trachtenberg J, et al. Population based survival data on urachal tumors. J Urol. 2006;175(6):2042–2047.
4. Siefker-Radtke AO, Gee J, Shen Y, et al. Multimodality management of urachal carcinoma: The M.D. Anderson Cancer Center experience. J Urol. 2003;169(4):1295–1298.
5. Herr HW, Bochner BH, Sharp D, et al. Urachal carcinoma: contemporary surgical outcomes. J Urol. 2007;178(1):74–78.
6. Mohile SG, Schleicher L, Petrylak DP. Treatment of metastatic urachal carcinoma in an elderly woman. Nat Clin Pract Oncol. 2008;5:55–58.
ADDITIONAL READING
• Laboccetta LT, Picard JC. The urachus: A review and update. AUA Update Series. 2012;31:89–96.
• Siefker-Radtke A. Urachal Adenocarcinoma: A Clinician’s Guide for Treatment. Semin Oncol. 2012;39(5):619–624.
See Also (Topic, Algorithm, Media)
• Bladder Cancer, Adenocarcinoma
• Umbilical Abnormalities, Urologic considerations
• Urachal Abnormalities
• Urachal Carcinoma Images 
• Urachal Carcinoma Staging Systems
CODES
ICD9
• 188.7 Malignant neoplasm of urachus
• 198.1 Secondary malignant neoplasm of other urinary organs
ICD10
• C67.7 Malignant neoplasm of urachus
• C79.11 Secondary malignant neoplasm of bladder
CLINICAL/SURGICAL PEARLS
• It is difficult to differentiate between an infection and urachal carcinoma for symptomatic urachal lesions.
• There should be a high clinical suspicion for urachal carcinoma in any adult with an urachal lesion.
• Any tumor arising from the dome of bladder should be considered urachal carcinoma until proven otherwise.
• Surgical management of urachal carcinoma should involve a complete resection of the urachus and umbilicus with wide surgical margins.