Adenocarcinoma (urinary bladder)

Adenocarcinoma of the urinary bladder is rare and accounts for only ~1% of all bladder cancers (90% are transitional cell carcinomas).

Pathology

Metaplasia of urinary bladder induced by chronic irritation or infection can lead to adenocarcinoma. Pathological types of adenocarcinoma of the urinary bladder are:

  • mucinous adenocarcinoma
  • signet-ring type
  • papillary adenocarcinoma
  • not otherwise specified (NOS)

Bladder adenocarcinoma may be subclassified as primary (two-thirds are non-urachal and one-third are urachal ) or secondary (metastases).

Etiology

Radiographic features

CT
Non-urachal adenocarcinoma
  • diffuse bladder wall thickening
  • stranding of perivesical fat
  • regional lymphadenopathy
  • invasion of rectus muscles
Urachal adenocarcinoma
  • characteristically in the midline at the dome of the bladder, or along the course of urachus (from the bladder to umbilicus)
    • a midline, infraumbilical soft tissue mass with peripheral calcification is characteristically urachal adenocarcinoma unless proven otherwise (calcification in 70% of cases)
  • usually large tumors (5-6 cm) with prominent extravesical component
  • mixed solid-cystic appearance in most cases
MRI

Solid components of the tumor are isointense, while cystic mucinous component appears hyperintense on T2W images. Localizing a urachal carcinoma may be easier on the sagittal images.

Treatment and prognosis

Due to their extravesical location, urachal carcinomas present very late and thus carry a poor prognosis. Radical cystectomy is considered the treatment of choice. However, en bloc resection of the extravesical component, adjacent peritoneum and the abdominal wall is also needed.

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