Scrotoschisis as a Mechanism for Extracorporeal By Robert
D. Gongaware,
Anthony
M. Sussman, David M. Kraebber, Savannah, Georgia
Testicular Ectopia and Stephen
Michigan
l Only one case of a rare anomaly, a congenital defect in the integrity of the scrotal wall permitting egress of the testis to an ectopic extracorporeal location, has been previously reported. A second occurrence of this rare anomally is herein described with a proposed mechanism of occurrence. The condition is termed scrotoschisis. Copyright o 7997 by W.B. Saunders Company INDEX
WORDS:
Scrotoschisis;
ectopia
testis.
T
ESTICULAR ectopia is an uncommon congenital anomaly with a reported frequency of l.O%.’ The testis descends through the inguinal canal but then occupies a final abnormal position. The major sites include: a superficial inguinal pouch, the perineum, the femoral canal, the penopubic region, and the contralateral inguinal canal.’ In only one instance reported in the literature did an ectopic testis reside in an extracorporeal position through a defect in the scrotal wall.’ The present report describes experience with an additional case of a scrotal wall defect with an ectopic testicle and describes the mechanism of origin. CASE
REPORT
A 29-year-old white woman (gravida 6, para 4, abortus 2) delivered a 2,580-g infant boy via uncomplicated cesarean section following normal gestation of 36 weeks. The infant was examined and found to have a 0.75-cm circumscribed skin defect in the right superior hemiscrotum. The right testis, epididymis, and spermatic cord were lying free outside the scrotum (Fig 1). The remainder of the infant’s physical examination was normal. Five hours following delivery the scrotal defect was explored under general anesthesia. The testicular appendages and the testicle appeared grossly normal. The extruded spermatic cord was traced to the right groin. Within the scrotum attached to the right testicle was a bulb-like appendage filled with green gelatinous material. The medial aspect of the testis was anchored to the midline intrascrotal tissue and the testicle was placed in the scrotum. The scrotal wall was closed in two layers. The patient recovery was uneventful. The testes was determined to be in a satisfactory location at discharge. DISCUSSION
Hunter was the first to associate the gubernaculum with testicular descent during gestation.3 Other theories have been proposed attempting to explain this From the Memorial Medical Center, Inc, Savannah, GA. Address reprint requests to Robert D. Gongaware, MD, Memorial Medical Center, Inc, PO Box 23089, Savannah, GA 31403-3089. Copyright o 1991 by WB. Saunders Company 0022-3468/91/2612-0027$03.00/0
1430
Fig 1.
Preoperative
extracorporeal
teeticular
ectopia.
process. They include a theory by Seiler that states the cremaster fibers run up the fibromuscular gubernaculum and pull the testis into the scrotum, and a theory of Cloquet, Hollingshead, and Wells that compares testicular descent to inguinal hernias with the testicular tunics and the cremaster being extensions of the abdominal wa11.3More recently, Wensign proposed that gubernacular swelling was responsible for testicular descent.4 Backhouse postulated that testicular descent was a rapid process under testosterone stimulation3 He proposed that maintenance of a primitive mesenchyme core free of skeletal muscle as well as encroachment by developing body structures was responsible for testicular descent. Backhouse theorized that the gubemacular mesenchyme increases in bulk by increasing intracellular glycosaminoglycans resulting in a gubernacular mesenchyme resembling Wharton’s jelly of the postnatal umbilical cord. The scrotal wall dilates and a separation zone forms between the wall and the distal portion of gubernaculum, which resembles a jelly-filled bulb free within the scrotum. The gubernacular mesenchyme in the inguinal canal undergoes rapid growth with distal extension of the cremaster muscle along the outer surface. The processus vaginalis forms by active invasion of the peritoneal epithelium into the gubernaculum, leaving
JournalofPediatricSurgery,
Vol26,
No 12 (December),
1991: pp 1430-1431
TESTICULAR
ECTOPIA
SECONDARY
1431
TO SCROTOSCHISIS
a central tube of mesenchyme surrounded by differentiated cremaster. Scrotal growth and dilation of the distal gubernaculum create a conical column of mesenchyme with a relatively small testis at the apex. The inguinal canal is dilated and held open by this undifferentiated mesenchyme. Given adequate length of the testicular vessels and the vas deferens, the testicle descends into the scrotum as the gubernacular mesenchyme shortens. With descent complete, the distal gubernaculum differentiates into fascia in relation to the testis and the epididymis. The gubernacular mesenchyme separated by the processus vaginalis and containing the cremaster differentiates into external and internal spermatic fascia. To develop, this condition requires the development of a scrotal wall defect resulting in the ectopic extracorporeal testicular descent. Mesenchyme in the scrotal swellings becomes gubernaculum centrally, and the peripheral portions differentiate to form the scrotal wall. Failure of this mesenchyme to differentiate into the scrotal wall could leave a defect where
the gubernaculum was covered only by a thin layer of epithelium. With development of the separation zone and scrotal dilation, the epithelium would be separated from the jelly-like gubernacular bulb. Lacking sufficient supporting structure, rupture or avascular necrosis occur leaving a scrotal wall defect. Rapid growth of the gubernacular mesenchyme could force the distal gubernacular bulb through this defect. Further testicular descent then follows the normal process with the processus vaginalis extending distally and the formation of a central mesenchyme core surrounded by developing cremaster. Shortening of this undifferentiated gubernacular mesenchyme would result in testicular descent through the scrotal wall defect, the final result being an ectopic extracorporeal testicle surrounded by normal tunics with a residual distal jelly-like gubernacular bulb. ACKNOWLEDGMENT The authors thank John F. Redman, MD, and John P. Gearhart, MD, for their consultation on possible embryologic etiologies.
REFERENCES 1. Rajfer J: Congenital anomalies of the testis, in Walsh PC, Gittes RF, Perlmutter AD, et al (eds): Campbell’s Urology. Philadelphia, PA, Saunders, 1986, pp 1947-1968 2. Pacha MR: Intauterine testicular extravasation. J Med Assoc Ala 52:43, 1983
3. Backhouse KM: Embryology of testicular descent and maldescent. Ural Clin North Am 9:315-325, 1982 4. Hadziselimovic F: Testicular development, in Gillenwarer JY, Grayhack JT, Howards SS, et al (eds): Adult and Pediatric Urology. Chicago, IL, Year Book, 1987, pp 1932-1947
D. Gongaware,
Anthony
M. Sussman, David M. Kraebber, Savannah, Georgia
Testicular Ectopia and Stephen
Michigan
l Only one case of a rare anomaly, a congenital defect in the integrity of the scrotal wall permitting egress of the testis to an ectopic extracorporeal location, has been previously reported. A second occurrence of this rare anomally is herein described with a proposed mechanism of occurrence. The condition is termed scrotoschisis. Copyright o 7997 by W.B. Saunders Company INDEX
WORDS:
Scrotoschisis;
ectopia
testis.
T
ESTICULAR ectopia is an uncommon congenital anomaly with a reported frequency of l.O%.’ The testis descends through the inguinal canal but then occupies a final abnormal position. The major sites include: a superficial inguinal pouch, the perineum, the femoral canal, the penopubic region, and the contralateral inguinal canal.’ In only one instance reported in the literature did an ectopic testis reside in an extracorporeal position through a defect in the scrotal wall.’ The present report describes experience with an additional case of a scrotal wall defect with an ectopic testicle and describes the mechanism of origin. CASE
REPORT
A 29-year-old white woman (gravida 6, para 4, abortus 2) delivered a 2,580-g infant boy via uncomplicated cesarean section following normal gestation of 36 weeks. The infant was examined and found to have a 0.75-cm circumscribed skin defect in the right superior hemiscrotum. The right testis, epididymis, and spermatic cord were lying free outside the scrotum (Fig 1). The remainder of the infant’s physical examination was normal. Five hours following delivery the scrotal defect was explored under general anesthesia. The testicular appendages and the testicle appeared grossly normal. The extruded spermatic cord was traced to the right groin. Within the scrotum attached to the right testicle was a bulb-like appendage filled with green gelatinous material. The medial aspect of the testis was anchored to the midline intrascrotal tissue and the testicle was placed in the scrotum. The scrotal wall was closed in two layers. The patient recovery was uneventful. The testes was determined to be in a satisfactory location at discharge. DISCUSSION
Hunter was the first to associate the gubernaculum with testicular descent during gestation.3 Other theories have been proposed attempting to explain this From the Memorial Medical Center, Inc, Savannah, GA. Address reprint requests to Robert D. Gongaware, MD, Memorial Medical Center, Inc, PO Box 23089, Savannah, GA 31403-3089. Copyright o 1991 by WB. Saunders Company 0022-3468/91/2612-0027$03.00/0
1430
Fig 1.
Preoperative
extracorporeal
teeticular
ectopia.
process. They include a theory by Seiler that states the cremaster fibers run up the fibromuscular gubernaculum and pull the testis into the scrotum, and a theory of Cloquet, Hollingshead, and Wells that compares testicular descent to inguinal hernias with the testicular tunics and the cremaster being extensions of the abdominal wa11.3More recently, Wensign proposed that gubernacular swelling was responsible for testicular descent.4 Backhouse postulated that testicular descent was a rapid process under testosterone stimulation3 He proposed that maintenance of a primitive mesenchyme core free of skeletal muscle as well as encroachment by developing body structures was responsible for testicular descent. Backhouse theorized that the gubemacular mesenchyme increases in bulk by increasing intracellular glycosaminoglycans resulting in a gubernacular mesenchyme resembling Wharton’s jelly of the postnatal umbilical cord. The scrotal wall dilates and a separation zone forms between the wall and the distal portion of gubernaculum, which resembles a jelly-filled bulb free within the scrotum. The gubernacular mesenchyme in the inguinal canal undergoes rapid growth with distal extension of the cremaster muscle along the outer surface. The processus vaginalis forms by active invasion of the peritoneal epithelium into the gubernaculum, leaving
JournalofPediatricSurgery,
Vol26,
No 12 (December),
1991: pp 1430-1431
TESTICULAR
ECTOPIA
SECONDARY
1431
TO SCROTOSCHISIS
a central tube of mesenchyme surrounded by differentiated cremaster. Scrotal growth and dilation of the distal gubernaculum create a conical column of mesenchyme with a relatively small testis at the apex. The inguinal canal is dilated and held open by this undifferentiated mesenchyme. Given adequate length of the testicular vessels and the vas deferens, the testicle descends into the scrotum as the gubernacular mesenchyme shortens. With descent complete, the distal gubernaculum differentiates into fascia in relation to the testis and the epididymis. The gubernacular mesenchyme separated by the processus vaginalis and containing the cremaster differentiates into external and internal spermatic fascia. To develop, this condition requires the development of a scrotal wall defect resulting in the ectopic extracorporeal testicular descent. Mesenchyme in the scrotal swellings becomes gubernaculum centrally, and the peripheral portions differentiate to form the scrotal wall. Failure of this mesenchyme to differentiate into the scrotal wall could leave a defect where
the gubernaculum was covered only by a thin layer of epithelium. With development of the separation zone and scrotal dilation, the epithelium would be separated from the jelly-like gubernacular bulb. Lacking sufficient supporting structure, rupture or avascular necrosis occur leaving a scrotal wall defect. Rapid growth of the gubernacular mesenchyme could force the distal gubernacular bulb through this defect. Further testicular descent then follows the normal process with the processus vaginalis extending distally and the formation of a central mesenchyme core surrounded by developing cremaster. Shortening of this undifferentiated gubernacular mesenchyme would result in testicular descent through the scrotal wall defect, the final result being an ectopic extracorporeal testicle surrounded by normal tunics with a residual distal jelly-like gubernacular bulb. ACKNOWLEDGMENT The authors thank John F. Redman, MD, and John P. Gearhart, MD, for their consultation on possible embryologic etiologies.
REFERENCES 1. Rajfer J: Congenital anomalies of the testis, in Walsh PC, Gittes RF, Perlmutter AD, et al (eds): Campbell’s Urology. Philadelphia, PA, Saunders, 1986, pp 1947-1968 2. Pacha MR: Intauterine testicular extravasation. J Med Assoc Ala 52:43, 1983
3. Backhouse KM: Embryology of testicular descent and maldescent. Ural Clin North Am 9:315-325, 1982 4. Hadziselimovic F: Testicular development, in Gillenwarer JY, Grayhack JT, Howards SS, et al (eds): Adult and Pediatric Urology. Chicago, IL, Year Book, 1987, pp 1932-1947
