Imaging description

Outpouchings of the bladder may mimic cystic or fluid-filled pelvic masses at cross-sectional imaging (Figures 87.1–87.3) [1–4]. Accumulation of excreted FDG in such outpouchings may suggest the diagnosis of a malignant mass at PET [5–7] (Figure 87.4). Such outpouchings may be true diverticula (either congenital or acquired) or bladder ears. The term bladder ear strictly refers to lateral outpouchings of the bladder in infants, sometimes extending into the inguinal canal or femoral ring, which are usually detected incidentally during cystography or intravenous urography and are thought to be a normal developmental variant [8]. In practice, the term bladder ear is used less precisely to refer to any lateral protrusion or extension of the bladder that simulates a cystic mass adjacent to the bladder.

Importance

Misinterpretation of a bladder diverticulum as a cystic mass at cross-sectional imaging or as a metastatic focus at PET may result in needless patient anxiety and unnecessary treatment or workup such as cyst aspiration, biopsy, or surgery [1].

Typical clinical scenario

Bladder diverticula are usually acquired and due to chronic bladder outlet obstruction, most commonly in older men with benign prostatic hyperplasia. Congenital bladder diverticula are rare and most occur in boys immediately adjacent to the ureteral orifice (so-called Hutch diverticula). Bladder herniation into the inguinal canal is usually seen in men over 50 years of age [5].