Huge filling defect in the bladder caused by intravesical enlargement of the prostate.

Abstract

When the prostate gland grows massively in an intravesical direction, the diagnosis both radiographically and clinically may be difficult. An awareness by the radiologist and urologist of the radiographic features of intravesical enlargement of the prostate is important for proper diagnosis and management. This report is a presentation of the radiologic findings as well as a discussion of the differential diagnostic possibilities in such cases. Anatomical Considerations Solitary intravesical enlargement of the prostate may be due to enlargement of either the subcervical glands of the prostate or the median lobe (1). Subcervical gland enlargement was more than twice as frequent as median lobe enlargement in a series of 222 patients with benign prostatic hypertrophy studied by Randall (2). In addition to the outer or true prostatic glands making up the lateral, anterior, posterior, and median lobes, the normal prostate contains inner or periurethral glands which are located in both the mucosa and submucosa of the urethral walls just below the bladder neck. The most important of these is the subcervical group, or Albarran's glands, lying inside the internal sphincter beneath the mucosa of the bladder neck. They have no functional relationship to the prostate (3). When hypertrophy starts in these gland acini, however, development of a small rounded nodule or spheroid just infra-sphincteric and beneath the vesical orifice occurs. This nodule rapidly becomes spheroidal in shape during growth, and it protrudes first into the urethral lumen and then tends to push up through the internal sphincter. Pedunculation appears early, and as the mass grows it becomes intravesical and is covered only by its mucous membrane (Figs. 1 and 2). The pedunculated appearance is characteristic and constant. This enlargement is usually small to moderate but occasionally can attain enormous size as in the eases presented in this report. Median lobe enlargements also tend to push intravesically and produce marked filling defects in the floor of the bladder (4). This lobe develops in the floor of the urethra near the median line between the bladder neck and the orifices of the ejaculatory ducts and the utricle (3). The enlargements in this area start in the posterior urethra. They follow the line of least resistance and progress as a mass up through the vesical orifice (bladder outlet) and into the bladder, elevating the floor of the trigone. In cases with large solitary median lobe hypertrophy, growth is always upward and intravesical in direction. Clinical Considerations The clinical diagnosis of solitary sub-cervical or median lobe hypertrophy can be quite difficult. Rectal examination is not only unsatisfactory but may even be misleading for, if the lobe grows intravesically, it cannot be felt through the rectum.