Prepared by Juan R. Rodríguez, MD , a second-year Resident, and Anil Malik, MD , a third-year Resident, from the Department of Radiology at Louisiana State University Health Science Center, Shreveport, LA.

CASE SUMMARY

The patient is a 53-year-old white man with a 2-year history of intermittent right flank pain, microhematuria, discomfort in lower extremities, and constipation. He also suffers from hypertension and non­insulin-dependent diabetes mellitus. The patient is obese with no abnormal findings on physical examination. Imaging studies performed during follow-up included intravenous pyelogram (IVP) (Figures 1, 2, and 3), barium enema (BE) (Figure 4), computed tomography (CT) (Figure 5), sonographic evaluation of lower extremity venous systems, and cystoscopy. Direct visualization of the bladder lumen by cystoscopy was normal. Laboratory values were: BUN 12, and creatinine 0.8.

DIAGNOSIS

Pelvic lipomatosis

IMAGING FINDINGS

On plain abdominal X-rays, increased radiolucency of the perivesical area is a sign of the presence of pelvic lipomatosis (PL) and may be the first imaging abnormality noticed (Figure 1). Images obtained on IVP show the abnormal shape and position of the bladder with the appearance of an inverted teardrop caused by extrinsic compression. The ureters are dilated, tortuous, and displaced laterally (Figures 2 and 3). The barium enema examination demonstrated elongation and symmetrical extrinsic compression of the rectum and cephalad displacement of the sigmoid colon. The appearance of the rectosigmoid in this condition has been named tower rectum (Figure 4). The abdominal CT scan reveals that the bladder and rectosigmoid are surrounded and displaced by fat tissue (attenuation coefficient: ­40 to ­100 Hounsfield units [HU]) (Figure 5).

DISCUSSION

Pelvic lipomatosis is a disease of unknown cause, characterized by overgrowth of mature, nonmalignant fat cells in the pelvic region, especially in perivesical and perirectal spaces. It is a rare disease; the incidence of PL in the United States was estimated as 0.6 to 1.7 per 100,000 hospital admissions between 1967 and 1975. ¹ It may be more common than is indicated by the number of reports published, however. Pelvic lipomatosis is more frequent in males and African Americans. ² In 1959, Engels ³ first described 5 patients with bizarre deformities of the sigmoid colon and bladder, which were discovered on barium enema and cystography. The clinical presentation of PL is related to the compressive phenomenon on the urinary system (increased frequency, dysuria, nocturia, and hematuria), lower intestinal tract (constipation, tenesmus, rectal bleeding, and ribbon-like stools with mucus), and vascular system (edema of lower extremities).

Several authors have developed theories to explain its cause. It was initially suggested that PL results from chronic lower urinary-tract infection. ^3,4 When such infection is present in these patients, the distribution of the fat in the pelvis may be the result rather than its cause. ⁵ Pelvic lipomatosis has been linked to obesity ⁶ ; however, weight loss as therapy has not shown an improvement of the disease. Other theories connect PL with an endocrine dysfunction, but in only a small amount of cases was an endocrine abnormality found, such as diabetes mellitus or Cushing's disease. ^6,7

The differential diagnosis of the bladder deformity typical of PL includes several other conditions. Such deformity may result from hypertrophy of the iliopsoas muscles, ⁸ retroperitoneal fibrosis, ⁹ large pelvic abscess, or a large hematoma, usually due to trauma or anticoagulation therapy. ¹⁰ Additionally, collateral venous circulation from vena cava obstruction, ¹⁰ large iliac artery aneurysms, ¹¹ adenopathy from lymphoma, and prostatic carcinoma ^10,11 may cause a tear-drop shaped bladder and rectal extrinsic compression.

A conservative approach, the use of symptomatic treatment and follow-up, is indicated in cases with minor symptoms and with no repercussion over the renal function. In a review of this topic, Heyns ² describes various therapeutic options currently in use for treatment of PL. Conservative alternatives, such as long-term antimicrobial treatment, steroids, or dietary control, are ineffective. ¹² Some authors have tried radiotherapy without success. ¹³ Upper-tract urinary diversion is needed for patients with severe symptoms and/or evidence of urinary obstruction with deterioration of the renal function. Several techniques are described in the literature. ^9,11 Halachmi et al ¹⁴ reported the case of a 60-year-old man with PL that caused severe urinary tract obstruction, which was treated successfully with the use of an ultrasonic-assisted lipectomy device and reimplantation of the ureters at the bladder dome.

Although the condition does not show progression in most cases, it is impossible to predict which patients will experience deteriorating renal function. There is no evidence to support the suggestion of Carpenter, ¹² who stated that the prognosis of PL is worse in young men than in older patients. Follow-up of patients with PL is important to detect those in whom PL evolves and causes renal function deterioration. Urinary diversion may eventually be required to prevent obstructive uropathy from causing end stage renal disease.

ACKNOWLEDGMENTS

The authors thank Dr. Horacio B. D'agostino for his constant support and efforts as Chairman of our department; and would also like to thank Mrs. Evelyn Morris, radiologic technician, for her assistance.