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A 27-year-old Hispanic man presents to an emergency department in New Jersey in August 2014 after seeing blood in his urine earlier that day. He tells clinicians that although he has no trouble urinating, he has had vague abdominal pain for the past 4 months.

When answering questions about his medical history, the patient notes that he was born in Peru and that his father had colon cancer. The patient is not a smoker, drinks alcohol only occasionally at social events, and has been working at UPS for the past few years; his job involves loading trucks, but he is not aware of any chemical exposure.

A computed tomography (CT) scan of the abdomen and pelvis without contrast identifies a partially calcified mass at the dome of the urinary bladder, with infiltration of the adjacent lower abdominal mesentery.

Clinicians follow up with a multiphasic post-contrast CT scan of the abdomen/pelvis which also reveals a coarsely calcified mass at the urinary bladder dome, with reticulation of the mesenteric fat with nodular mesenteric implants indicating peritoneal carcinomatosis.

After arriving at this probable diagnosis, the medical team performs a cystoscopy with transurethral resection of the bladder tumor, places a right ureteral stent, and takes a biopsy of the bladder tissue. The tumor is found to be too extensive to be resected completely.

Based on findings of the dome-biopsy, clinicians diagnose urachal primary mucinous adenocarcinoma with prominent signet ring features. The tumor has extended into the subepithelial connective tissues, and the stage is pT1 (according to the modified International Union for Cancer Control staging criteria); the biopsy sample does not allow clinicians to establish a higher stage.

Immunohistochemical analysis shows that the tumor cells are strongly positive for cytokeratin (CK)20 and CDX2 and negative for p53, CK7, keratin 903, thrombomodulin, and p63.

Approximately 2 months after the patient's presentation to the emergency department, he is given a 6-week course of Bacillus Calmette-Guérin intravesical chemotherapy, and has a good response.

Discussion

Clinicians presenting this of a 27-year-old man with no significant risk factors note that young adults are rarely diagnosed with bladder cancer, and it is even more unusual to encounter a case of mucinous adenocarcinoma, which accounts for less than 2% of all cases.

The usual age of a patient diagnosed with bladder cancer is about 70. The authors note that in rare cases in children and young adults, the cancer tends to present as a low-grade, non-invasive disease.

The lack of research into the etiology or prognosis in young patients leaves the characteristics of bladder neoplasms in younger versus older patients a topic of debate in the medical literature.

As one of the most common forms of malignancies involving the urinary system, urothelial carcinoma of the bladder accounts for about 90% of bladder cancers that occur in the U.S. and Western Europe, affecting about three times as many men as women.

The disease is associated with numerous , including smoking (associated with 30-50% of cases) and workplace/chemical exposures (estimated to account for up to 25% of all cases); studies show that workers in the trucking, dye, rubber, textile, leather, and chemical industries in particular have a higher risk for bladder cancer.

An estimated 50%-60% of primary adenocarcinomas of the urinary bladder stem from the bladder base; most remaining cases are associated with urachal remnants. The case authors cite a theory suggesting that caused by chronic irritation, and although those arising in areas of urachal remnants may differ from those at the base, these malignancies share some behavioral and pathologic characteristics.

Mucinous adenocarcinomas are made up primarily of lakes of extracellular mucin located within collections of tumor cells that make up at least half of the tumor mass, the authors explain.

There are currently no established definitions or diagnostic criteria for mucinous carcinoma: some early criteria have required an area ratio of more than 60%.

The 2010 World Health Organization classification defines a mucinous carcinoma as an adenocarcinoma in which at least 50% of the lesion is composed of pools of extracellular mucin; these criteria are reportedly associated with a and increased survival compared with non-mucinous adenocarcinoma.

The case of this patient is a rare documentation of a mucinous adenocarcinoma arising from the dome of the bladder rather than the base, and diagnosed in a young patient with no evidence of a significant risk factor to suggest bladder cancer, which indicates the potential for idiopathic as well as undiscovered risk factors for bladder cancer, the authors note.

They cite a comparing age, gender, smoking status, and occupational exposure in individuals with and without bladder cancer that identified significant differences in the following:

• Smoking status: Of patients with bladder cancer, 73% were at least one-time smokers compared with 53.3% of controls; and were also much heavier smokers: 43.1 mean pack-years, compared with 28.8 for controls (P<0.0001)

• Occupations: Increased risk for jobs in the medical/health field (OR 2.17, 95% CI 1.21-3.92); similar results have been reported for waiters and bartenders, and borderline significant associations have been observed in electrical assembly, installation, and repair, and law/jurisprudence; the study also notes a nonsignificant elevated risk of urothelial bladder cancer in occupations associated with motor freight, general farming, and structural work

Therefore, the case authors note, despite a lack of a clear link between work history and bladder cancer risk, numerous different occupations have shown a slight correlation with the disease.

In the case of this patient, while he had been at his job loading trucks for less than 10 years, a long-term history of occupational exposure may reflect secondary effects of exposure to chemicals or other carcinogens.

Since such correlations cannot be proven in this young, non-smoking patient, the case illustrates a rare incidence of mucinous adenocarcinoma with no known risk factor, the authors observe, noting that his tumor expressed the CK20 and CDX2 markers that have previously been shown to be prominent in some other malignancies, such as colorectal cancer.

This raises questions as to whether a family history of colon cancer increases the risk of bladder cancer at a younger age, and whether a family history of colon cancer with particular markers should trigger early screening for bladder cancer.

Conclusion

The case authors conclude that while multiple environmental and genetic factors may contribute to the risk of urothelial tumors in young patients, this case of a young patient diagnosed in the absence of evident risk factors demonstrates the unclear etiologies of this form of malignancy, and brings into question whether there is any association with bladder cancer and the development of other cancers.

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