Findings:

1. 20 minute film from an IVP demonstrates the characteristic tear-shaped bladder. Note increased lucency around the bladder and elevation of bladder floor.
   
2. AP film from a barium enema reveals a narrow elongated rectum.

Discussion: Pathologically this entity is a benign overgrowth of adipose tissue within the pelvis. Associated minimal fibrotic and inflammatory components compressing soft tissue structures within the pelvis. This deformity is generally not progressive. Specimen demonstrates normal fat and varying amounts of fibrotic tissue. Etiology is unknown. There is a male to female predominance of 10:1. No obvious racial predominance, age spike (9-83 years), or association with obesity.

Most often identification of the pelvic lucency is an incidental finding in asymptomatic patients. A weak association of urinary frequency, recurrent urinary tract infections, fever, low pain or flank pain can be found. Occasionally mild constipation is reported.

Urographic findings include an elongated bladder or a symmetric inverted pear or tear shape configuration. The bladder appears fixed and elevated above the symphysis pubis. As a result of bladder elevation the posterior urethra appears elongated on voiding cystography. Reports of difficulty during cystoscopy in these patients can be found.

Physical examination is not specific. Sensation of suprapubic or lower abdominal fullness during abdominal examination. The prostate is palpated in an unusually high position on rectal examination.

Laboratory studies are noncontributory. Rarely patients progress to ureteral obstruction requiring ureteral diversion. This generally occurs late in the disease, and the stated incidence is 40% within five years.

The ureters are displaced medially and superiorly. Mild to moderate loss of ureteral peristalsis can be seen in 50% of the patients.

Barium enema reveals that the rectum appears elongated and narrow. The increase in presacral space is more readily appreciated as well as increased space between the bladder and rectum. The rectosigmoid and sigmoid may be displaced out of the pelvis and the sigmoid colon may appear stretched. Obstruction of these structures is not characteristic and other causes must be ruled out.

In cases where the hyperlucency is readily evident, plain film and urographic findings are very suggestive. In many cases the fibrotic component predominates and CT evaluation is recommended for confirmation. In these cases differential considerations include:

1. Infiltrative carcinoma from the prostate or gastrointestinal origin
2. Adenopathy/lymphoma
3. Metastatic carcinoma
4. Spontaneous pelvic hematoma
5. IVC obstruction
6. Perivesicle fluid, ruptured bladder

1. Witten DM, Myers GH, Utz DC. Emmett's Clinical Urography.
   Philadelphia, Pa: W. B. Saunders Co, 1977;2233-2237.
   
2. Lalli AF. The Tailored Urogram. Chicago, Il: Year Book
   Medical Publishers, Inc., 1973.
   
3. Bryan PJ, Cohen WN, Seidelman FE. Computed Tomography of the Abdomen.
   In: Haaga JR, Alfidi RJ, ed. Computed Tomography of the Whole Body. Princeton, NJ:
   C.V. Mosby Company, 1985;253.