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Ectopic Prostatic Adenoma in Retrovesical Space
0022-534 7/87 /1375-0998$02.00/0 Vol. 137, May
THE JOURNAL OF UROLOGY
Copyright © 1987 by The Williams & Wilkins Co.
Printed in U.S.A.
ECTOPIC PROSTATIC ADENOMA IN RETROVESICAL SPACE SHU YASUKAWA, HIDEO AOSHI AND MASATO TAKAMATSU From the Department of Urology, Izumisano Municipal Hospital, Osaka, Japan
ABSTRACT
We report a rare case of ectopic prostatic adenoma in the retrovesical space. In 1912 Lowsley described that the neonatal prostate consisted of 7 lobes, that is anterior, posterior, right lateral, left lateral, median, subcervical and subtrigonal. 1 Prostatic tissue outside of the 7 lobes was described as ectopic and most of those cases reported were so-called prostatic polyps. Ectopic prostatic tissue in the bladder also has been reported. However, there have been few reports of ectopic prostatic tissue outside of the urinary tract. We report a case of an ectopic prostatic adenoma in the retrovesical space. CASE REPORT
K. M., a 74-year-old man, was hospitalized because of urinary frequency and a sensation of residual urine. Physical examination revealed no specific findings. No masses were palpated on rectal examination except for a normal-sized prostate. The urinary sediment contained 20 to 30 red cells per high power field. An excretory urogram showed a normal upper urinary tract. Cystoscopic examination revealed no abnormality except for an elevation behind the left ureteral orifice. At urethrocystography the bladder was displaced to the upper and right side owing to external pressure (fig. 1). Computerized tomography (CT) of the pelvis demonstrated a high density mass arising from the lower pelvis posterior to the bladder and compressing the bladder to the right side (fig. 2). A vesiculogram was within normal limits. No abnormal signs were noted on a pelvic angiogram. At operation a well encapsulated round tumor was found to the left of the bladder. The bladder and prostate were freed easily from the tumor. There was no continuity between the tumor and the prostate. The tumor measured 7.5 x 5.5 x 4.0 cm. and weighed 90 gm. It was encapsulated by fibrous connective tissue and had a yellowish cut surface with many small brown nodules (fig. 3). ___ Mic_r_o_s_c_opicall}',__the .. tumor was composed of fibromuscular stroma and cystically dilated glands with 2 epithelial layers, and an inner columnar and outer cuboidal epithelium. These glands contained corpora amylacea (fig. 4). Immunohistological stain with peroxidase-antiperoxidase indicated the presence of prostatic specific antigen in the epithelial cells of the glands.
Fm. 1. Urethrocystogram demonstrates displacement of bladder to upper right side owing to external pressure.
DISCUSSION
The precise origin of ectopic prostatic tissue remains a matter of speculation. The prostatic glands usually arise from a series of endodermal buds from the lining of the future prostatic urethra at the end of the third month of embryonic development. These buds grow into the surrounding mesenchyma that differentiates into the muscular and connective tissue components of the glands. According to Gutierrez and Nesbit, the source of ectopic prostatic tissue in the urethra and bladder can be based on 3 theories: 1) the structure arising during embryological development as evaginations of the urethra and normally undergoing regression, 2) misplaced tissue representing stranded nests of prostatic mesodermal cells or 3) metaplaAccepted for publication November 25, 1986.
Fm. 2. CT scan shows high density mass arising from lower pelvis posterior to bladder and compressing bladder to right side. 998
ECTOPIC PROSTATIC ADENOMA IN RETROVESICAL SPACE
FIG. 3. Cut surface of resected tumor
sia of the transitional epithelium. 2 Theories 1 and 3 do not explain the dislocation of the prostatic gland in our case. Therefore, the only possible explanation seems to be that the embryonic prostatic tissue migrated and became isolated. The persistent vestige begins to develop in adult life and hormonal stimulation may have a pathogenic role. Spiro and Levine postulated that tissue representing nests of prostatic cells could migrate from the internal sphincter muscle fibers at the bladder neck cephalad to a more proximal location underneath the bladder. 3 Ectopic prostatic tissue outside of the urinary tract is rare, with only 2 cases reported in the literature. 3 •4 In 1981 Tokumitsu and associates described a retroperitoneal lipoma with prostatic tissue, which they believed developed from the wolffian vestige. 5 However, the tumor may have been a type of teratoma, because it also included other urogenital tissue, such as the urethra, bladder and seminal vesicle. Our case resembled adenoma of the original prostatic gland macroscopically and
FIG. 4. Photomicrograph of resected tumor shows characteristic prostatic glands composed of 2 epithelial layers. Some glands contain corpora amylacea. Reduced from XlOO.
pathologically, which to our knowledge has never been described in the literature. REFERENCES
1. Lowsley, 0. S.: The development of the human prostate gland with reference to the development of other structures at the neck of the urinary bladder. Amer. J. Anat., 13: 299, 1912. 2. Gutierrez, J. and Nesbit, R. M.: Ectopic prostatic tissue in bladder. J. Urol., 98: 474, 1967. 3. Spiro, L. H. and Levine, B.: Ectopic subvesical prostatic tissue. J. Urol., 112: 631, 1974. 4. Marini, F., Perego, S. and Valente, R.: Ectopia prostatica: una osservazione. Urologia, 45: 179, 1978. 5. Tokumitsu, S., Tokumitsu, K., Takeya, M. and Takeuchi, T.: Developmentally heterotopic urogenital tissue in a retroperitoneal lipoma with hematopoiesis. Acta Path. Jap., 31: 289, 1981.
THE JOURNAL OF UROLOGY
Copyright © 1987 by The Williams & Wilkins Co.
Printed in U.S.A.
ECTOPIC PROSTATIC ADENOMA IN RETROVESICAL SPACE SHU YASUKAWA, HIDEO AOSHI AND MASATO TAKAMATSU From the Department of Urology, Izumisano Municipal Hospital, Osaka, Japan
ABSTRACT
We report a rare case of ectopic prostatic adenoma in the retrovesical space. In 1912 Lowsley described that the neonatal prostate consisted of 7 lobes, that is anterior, posterior, right lateral, left lateral, median, subcervical and subtrigonal. 1 Prostatic tissue outside of the 7 lobes was described as ectopic and most of those cases reported were so-called prostatic polyps. Ectopic prostatic tissue in the bladder also has been reported. However, there have been few reports of ectopic prostatic tissue outside of the urinary tract. We report a case of an ectopic prostatic adenoma in the retrovesical space. CASE REPORT
K. M., a 74-year-old man, was hospitalized because of urinary frequency and a sensation of residual urine. Physical examination revealed no specific findings. No masses were palpated on rectal examination except for a normal-sized prostate. The urinary sediment contained 20 to 30 red cells per high power field. An excretory urogram showed a normal upper urinary tract. Cystoscopic examination revealed no abnormality except for an elevation behind the left ureteral orifice. At urethrocystography the bladder was displaced to the upper and right side owing to external pressure (fig. 1). Computerized tomography (CT) of the pelvis demonstrated a high density mass arising from the lower pelvis posterior to the bladder and compressing the bladder to the right side (fig. 2). A vesiculogram was within normal limits. No abnormal signs were noted on a pelvic angiogram. At operation a well encapsulated round tumor was found to the left of the bladder. The bladder and prostate were freed easily from the tumor. There was no continuity between the tumor and the prostate. The tumor measured 7.5 x 5.5 x 4.0 cm. and weighed 90 gm. It was encapsulated by fibrous connective tissue and had a yellowish cut surface with many small brown nodules (fig. 3). ___ Mic_r_o_s_c_opicall}',__the .. tumor was composed of fibromuscular stroma and cystically dilated glands with 2 epithelial layers, and an inner columnar and outer cuboidal epithelium. These glands contained corpora amylacea (fig. 4). Immunohistological stain with peroxidase-antiperoxidase indicated the presence of prostatic specific antigen in the epithelial cells of the glands.
Fm. 1. Urethrocystogram demonstrates displacement of bladder to upper right side owing to external pressure.
DISCUSSION
The precise origin of ectopic prostatic tissue remains a matter of speculation. The prostatic glands usually arise from a series of endodermal buds from the lining of the future prostatic urethra at the end of the third month of embryonic development. These buds grow into the surrounding mesenchyma that differentiates into the muscular and connective tissue components of the glands. According to Gutierrez and Nesbit, the source of ectopic prostatic tissue in the urethra and bladder can be based on 3 theories: 1) the structure arising during embryological development as evaginations of the urethra and normally undergoing regression, 2) misplaced tissue representing stranded nests of prostatic mesodermal cells or 3) metaplaAccepted for publication November 25, 1986.
Fm. 2. CT scan shows high density mass arising from lower pelvis posterior to bladder and compressing bladder to right side. 998
ECTOPIC PROSTATIC ADENOMA IN RETROVESICAL SPACE
FIG. 3. Cut surface of resected tumor
sia of the transitional epithelium. 2 Theories 1 and 3 do not explain the dislocation of the prostatic gland in our case. Therefore, the only possible explanation seems to be that the embryonic prostatic tissue migrated and became isolated. The persistent vestige begins to develop in adult life and hormonal stimulation may have a pathogenic role. Spiro and Levine postulated that tissue representing nests of prostatic cells could migrate from the internal sphincter muscle fibers at the bladder neck cephalad to a more proximal location underneath the bladder. 3 Ectopic prostatic tissue outside of the urinary tract is rare, with only 2 cases reported in the literature. 3 •4 In 1981 Tokumitsu and associates described a retroperitoneal lipoma with prostatic tissue, which they believed developed from the wolffian vestige. 5 However, the tumor may have been a type of teratoma, because it also included other urogenital tissue, such as the urethra, bladder and seminal vesicle. Our case resembled adenoma of the original prostatic gland macroscopically and
FIG. 4. Photomicrograph of resected tumor shows characteristic prostatic glands composed of 2 epithelial layers. Some glands contain corpora amylacea. Reduced from XlOO.
pathologically, which to our knowledge has never been described in the literature. REFERENCES
1. Lowsley, 0. S.: The development of the human prostate gland with reference to the development of other structures at the neck of the urinary bladder. Amer. J. Anat., 13: 299, 1912. 2. Gutierrez, J. and Nesbit, R. M.: Ectopic prostatic tissue in bladder. J. Urol., 98: 474, 1967. 3. Spiro, L. H. and Levine, B.: Ectopic subvesical prostatic tissue. J. Urol., 112: 631, 1974. 4. Marini, F., Perego, S. and Valente, R.: Ectopia prostatica: una osservazione. Urologia, 45: 179, 1978. 5. Tokumitsu, S., Tokumitsu, K., Takeya, M. and Takeuchi, T.: Developmentally heterotopic urogenital tissue in a retroperitoneal lipoma with hematopoiesis. Acta Path. Jap., 31: 289, 1981.