Imaging features of primary mucinous adenocarcinoma of bladder outlet and urethra: a case report and literature review

Background: Primary bladder adenocarcinoma (PBA) only accounts for 2% of primary bladder cancers. PBA symptoms vary according to the volume, location, and the metastasis of the tumor. The most common symptoms include suprapubic pain, hematuria, dysuria, and bladder irritation. In the initial stage, the diagnosis of PBA is possibly delayed due to the lack of obvious symptoms. When diagnosed, up to 40% of patients are reported to have metastatic disease. PBA can occur anywhere in the bladder, especially the bottom, neck, and roof. However, the mass at the bladder outlet and urethra is a rare presentation of PBA. Through this rare case, when clinicians encounter similar patients, they can have richer ideas for diagnosis and treatment, which is helpful for the timely diagnosis and effective treatment. Case Description: A 62-year-old female was referred to an outpatient urology surgery service due to a 1-year history of narrowing of the urinary route and difficulties in urination. No significant abnormalities were found in other surgical examinations, and the patient denied having a genetic history or similar history in her family. Ultrasonography revealed a hypoechoic mass of 6.5 cm x 3.8 cm x 4.4 cm at the bladder outlet and urethra. Computed tomography (CT) plain scan and enhancing scan displayed that the wall of bladder was thickened, and soft tissue density was seen at the bladder outlet and urethra with slight enhancement and an unclear partial boundary. The mass was confirmed to be PBA. Conclusions: Primary mucinous adenocarcinoma of bladder usually detected in the posterior wall and trigone, but at the bladder outlet and urethra was rare. In this report, Imaging examination showed that the mass was located at the bladder outlet and urethra, and was finally confirmed by surgery. Due to the location of the growth, our patient's only symptoms were dysuria and urinary tract thinning, without hematuria, suprapubic pain, or bladder irritation. Timely diagnosis and treatment of this case depend on the findings of imaging examination. We describe the imaging features of this rare disease entity and the relevant literature review.