Pelvic lipomatosis: diagnosis and characterization by magnetic resonance imaging

While the number of reported cases of pelvic lipomatosis has been relatively small, this entity's prevalence is probably underestimated. Disease progression can cause hydroureteronephrosis and renal failure, and clinical follow-up is mandated after diagnosis. Diagnosis is based on detection of characteristic findings in conventional radiographs and computed tomographic (CT) images. We report here the magnetic resonance imaging (MRI) features of pelvic lipomatosis in 5 male patients, 2 of whom ultimately required placement of a ureteral stent to alleviate mechanical obstruction. Multiplanar MRI not only allows diagnostic confirmation comparable to that possible with CT but also provides delineation of cephalad displacement of the bladder base, elongation of the bladder neck and posterior urethra, and elevation of the prostate gland. The MR images show characteristic medial and superior displacement of the seminal vesicles and show fatty tissue separating the prostate gland from the rectum. The noninvasive nature and low biological risk of MRI are desirable features, particularly when serial evaluation of pelvic anatomic distortion is necessary.