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Ectopic Spleen in the Scrotum: Report of 2 Cases
Vol. 111, January Printed in U.S.A.
THE JOURNAL OF UROLOGY
Copyright© 1974 by The Williams & Wilkins Co
ECTOPIC SPLEEN IN THE SCROTUM: REPORT OF 2 CASES JAMES E. MAY
AND
CHARLES W. BOURNE*
From the Milwaukee Medical Clinic and Department of Laboratory Medicine, Columbia Hospital. Milwaukee, Wisconsin
Ectopic spleen in the scrotum or splenic gonadal fusion occurs rarely. Recent experience with 2 cases suggests a more frequent occurrence than has been reported. In 1969 Mendez and Morrow reviewed 53 cases and added one of their own. 1 Subsequently, 2 additional cases have been reported.2· 3 The inclusion of ectopic splenic tissue in the differential diagnosis of solid scrotal masses is emphasized in order to obviate unnecessary orchiectomy, especially in children. CASE REPORTS
Case 1. P. B., a 5-year-old white boy, had had a non-painful left scrotal mass for several years. His history included left inguinal herniorrhaphy and hydrocelectomy at another hospital when he was 8 weeks old. Physical examination revealed a 2 by 3 cm. sausage-shaped mass with a rubbery consistency, palpable just superior to the left testicle and not freely delineated from it. Laboratory studies were normal. Preoperative diagnosis was possible scrotal neoplasm. Scrotal exploration revealed a deep reddish tumor superior to the testicle and partially covered at its lateral-inferior aspect by the globus major of the epididymis. The tumor was encapsulated and easily dissected from the neighboring structures. There was no apparent cord of tissue extending proximally along the spermatic cord. The specimen measured 2.5 by 1.5 by 1.0 cm. and on cut section displayed the beefy color of normal spleen (fig. 1). Microscopic examination confirmed the typical histology of spleen. A postoperative scan outlined a normal intra-abdominal spleen. Case 2. T. S., a 17-month-old white male ectromelic infant, had a left scrotal mass (fig. 2). When he was 8 weeks old the diagnosis of left hydrocele had been made but when he was 10 months old the scrotal mass appeared more solid and enlarging. There was no history of maternal drug ingestion and parents and child had normal chromosomal studies. On physical examination there was complete absence of the right lower extremity and rudimentary elements of the remaining 3 appendages. The left scrotal sac contained a bluish, spongy mass which was palpable above and separate from the left testicle and which did not Accepted for publication June 29, 1973. * Requests for reprints: 3003 W. Good Hope Rd., Milwaukee, Wisconsin 53209. 1 Mendez, R. and Morrow, J. W.: J. Urol., 102: 598, 1969. 2 McNamara, J. H.: Pathology, 1: 331, 1969. 3 Venzoni, M., Pecchiai, L. and Monaco, L.: Minerva Chir., 25: 1299, 1970.
transmit light. Laboratory studies including an excretory urogram were normal. Preoperative diagnosis was an organizing hematocele or ectopic splenic tissue. Scrotal exploration revealed a beefy-red kidneyshaped mass within the tunica vaginalis and attached to the head of the epididymis by its own vascular pedicle (fig. 3). The vascular cord extended proximally along the spermatic cord as an easily dissectible separate structure. No inguinal hernia was found. A frozen section was consistent with splenic tissue. The specimen measured 2.6 by 1.5 by 1.3 cm. and was dark red on cut surface. Histologically, the mass was entirely composed of splenic tissue with somewhat enlarged splenic follicles (fig. 4).
FIG. 1. Cut section of splenic nodule CLASSIFICATION
All 58 cases of splenic gonadal fusion have occurred on the left side and the anomaly is more frequent in male subjects. Splenic gonadal fusions have been separated morphologically into 2 distinct groups: the continuous and discontinuous types.• In the continuous type, which has been described in 26 cases and was probably present in our case 2, there is a long cord-like structure which extends from the ectopic splenic mass to attach to the normal spleen. It may be pure fibrous or contain various amounts of splenic tissue. It follows closely the spermatic cord in the inguinal • Putschar, W. G. J. and Manion, W. C.: Amer. J. Path., 32: 15, 1956.
120
ECTOPIC SPLEEN IN SCROTUM
FIG. 2. Case 2. Newborn photograph
FIG. 3. Kidney-shaped splenic nodule with vascular pedicle isolated by Penrose drain. Forceps holds epididymis.
canal but at the internal ring it directly traverses the peritoneal cavity anterior to the intestines as it ascends to its termination at the normal spleen. In the discontinuous type, which was noted in 24 cases and present in our case 1, the encapsulated ectopic spleen is attached to the gonadal structures but is completely discrete and lacks any fibrous or splenic cord-like extension to the normal spleen. EMBRYOLOGY
The specific origin for splenic gonadal fusion remains unclear. Two theories have been proposed to explain the embryologic events. The splenic anlage is consistently visible in the fifth week of embryonic life as a proliferation of the surface peritoneal cells on the left side of the dorsal mesogastrium (greater omentum).' These cells break free and invade the underlying mesenchyme where they differentiate as spleen. As the embryonic gut tube rotates, the splenic anlage is thrown into close proximity with the left urogenital fold, which includes the gonadal mesoderm and mesonephric components. A segment of the mesonephros later becomes the epididymis and the mesonephric duct differentiates as the vas deferens. 5 Arey, L. B.: Developmental Anatomy. A Text-Book and Laboratory Manual of Embryology, 2nd ed. Philadelphia: W. B. Saunders Co., 1931.
Since the gonad begins to shift in a caudal di.rec tion during weeks 8 to 12 of gestation, its attachment with splenic tissue must occur between weeks 5 and 8. Sneath has proposed that slight inflammation cf the apposing peritoneal surfaces over the ridge and spleen could produce an adhesion or partial fusion between the 2 organs (fig. 5). 6 This theory would explain why splenic fusions occur exclusively with the left gonadal-mesonephric structures. During the subsequent caudal tion of the testis, the peritonealized adhesion would lengthen and ultimately develop as the intraperitoneal fibrous or splenic cord as seen the continuous type of fusion. Attenuation of tbe cord produced by tension might conceivably evolve to spontaneous rupture with resultant transforma tion into the discontinuous type of splenic fusion. A purely mechanical cause for rupture is suggested by the peculiar association of ectromelia splenic gonadal fusions. Patten described the appearance at 6 weeks of gestation of mesenchyme concentrations which represent the primordia of the 4 extremitieso 7 During the next 2 weeks rapid development takes place so that by 8 weeks well-molded miniatures represent all the appendages. The simultaneous teratogenic insult which results in peromelus and splenic gonadal fusions remains unexplained but it is noteworthy that the 8 ported cases of concomitant ectromelia occurred only with the continuous type of fusion. reduced activity and mobility of the ectromelic fetus in utero may be a factor in the preservation of the intraperitoneal cord. Sneath's theory has been refuted because, with a fusion of the splenic anlage from the wall of the omental sac to the gonadal ridge, the splenic cord should derive its blood supply from the omen tum. 8 Dissections have shown that the splenic cord is supplied by only the splenic and spermatic vessels. In Von Hochstetter' s case, the presence of 2 small. 'Sneath, W. A.: J. Anat. Physiol., 47: 340, 19130 7 Patten, B. M.: Human Embryology, 2nd ed. New York: Blakiston Co., 1953. • Von Hochstetter, A.: Virchow Arch. f. Path. Anat., 324: 36, 1953.
122
MAY AND BOURNE
FIG. 4. Case 2. Photomicrograph of ectopic spleen demonstrates splenic capsule and splenic follicles SNEATH'S THEORY
Mesonephric Duct
Gonadal Ridge
Stomach
6 WEEK EMBRYO
J:IG. 5. Schematic topographic microsection of 6-week embryo shows transcoelomic route for splenic gonadal
fusion.
pieces of spleen within the ovarian capsule could not be explained solely by an adhesion. Von Hochstetter postulated a retroperitoneal pathway for splenic anlage cells to come in contact with the gonad (fig. 6). The end of the caudal limiting fold, which connects the gonad with an area just medial and cranial to the splenic anlage, in essence represents the medial portion of the left pleuroperitoneal membrane. Thus, the anomaly would be explained by the abnormal appearance of splenic cells, either by misplacement or migration, along the caudal limiting fold. This theory could readily account for the discontinuous type of splenic gonadal fusions, although with misplaced splenic cells in the retroperitoneum one might expect a few cases of right-sided fusions. The latter has never been clinically documented. In order to
explain the continuous intraperitoneal cord, Von Hochstetter postulated a complete detachment of the cord from the retroperitoneal area to rest freely in the peritoneal cavity. Sommer gave credence to this theory because in his case the cord possessed a thin mesentery to the lateral abdominal wall in its entire length." DISCUSSION
Nearly half of the reported cases of splenic gonadal fusion have occurred in children. In order to avoid orchiectomy or epididymectomy, one must be aware of the possibility of ectopic splenic tissue in the scrotal sac. A number of cases were observed at autopsy but we noted 13 cases in which orchiectomy had been performed, often because of • Sommer, J. R.: Pediatrics, 22: 1183, 1958.
123
ECTOPIC SPLEEN IN SCROTUM
VON HOCHSTETTER'S THEORY
End of caudal
Gonadal Ridge Spleen Stomach
5 - 6 WEEK ErvJBRYO FIG. 6. Schematic topographic microsection of 5 to 6-week embryo shows completely retroperitoneal route for splenic gonadal fusion.
misinterpretation of the lesion as neoplasm. Since these splenic nodules are firm or rubbery, do not transmit light and may be poorly delineated from the normal scrotal contents, an operation is mandatory. An astute preoperative diagnosis still requires microscopic confirmation. Therefore, for practical purposes, recognition of a splenic mass at exploration is necessary in order to avoid orchiectomy. A number of clinical points may suggest the correct diagnosis. The lesion always occurs on the left side and may have been present for a long time. It is often associated with an indirect inguinal hernia and occasionally occurs with incomplete descensus of the left testicle. Scrotal spleens are generally located within the tunica vaginalis, are beefy red in color and are separated from the testicle and epididymis by a discrete capsule. Von Hochstetter documented splenic pieces within the ovary and Venzoni and associates found the spleen and testicle grossly fused together, although separate capsules were subsequently identified microscopically. In a few cases multiple splenic nodules have been found. The presence of the continuous cord is an additional hint as to the nature of the lesion. The
robust vascular cord, shown in figure 3, is separable from the normal anatomic structures of the spermatic cord. The suspected benign nature of the tumor can be confirmed by frozen section examination before extirpation. In many cases the excised testicle was described as atrophic or inflamed. In our cases the testicle was of similar size to its contralateral mate on palpation and <>nno,wo normal. Whether these testicles will later normal spermatogenesis is conjectural but should contribute to subsequent endogenous androgen production. There should be little reluctance to remove scrotal spleen since these nodules are truly accessory spleens. A normal intra-abdominal spleen has been invariably confirmed in cases further evaluated by transabdominal exploration, postoperative radioisotope splenograms or in a few cases at autopsy. SUMMARY
Two cases of splenic gonadal fusion are '""'""'''""'r1 The conflicting theories of embryogenesis are discussed. A clinical awareness of ectopic scrotal spleens can obviate inopportune radical scrotal operations, especially in children.
THE JOURNAL OF UROLOGY
Copyright© 1974 by The Williams & Wilkins Co
ECTOPIC SPLEEN IN THE SCROTUM: REPORT OF 2 CASES JAMES E. MAY
AND
CHARLES W. BOURNE*
From the Milwaukee Medical Clinic and Department of Laboratory Medicine, Columbia Hospital. Milwaukee, Wisconsin
Ectopic spleen in the scrotum or splenic gonadal fusion occurs rarely. Recent experience with 2 cases suggests a more frequent occurrence than has been reported. In 1969 Mendez and Morrow reviewed 53 cases and added one of their own. 1 Subsequently, 2 additional cases have been reported.2· 3 The inclusion of ectopic splenic tissue in the differential diagnosis of solid scrotal masses is emphasized in order to obviate unnecessary orchiectomy, especially in children. CASE REPORTS
Case 1. P. B., a 5-year-old white boy, had had a non-painful left scrotal mass for several years. His history included left inguinal herniorrhaphy and hydrocelectomy at another hospital when he was 8 weeks old. Physical examination revealed a 2 by 3 cm. sausage-shaped mass with a rubbery consistency, palpable just superior to the left testicle and not freely delineated from it. Laboratory studies were normal. Preoperative diagnosis was possible scrotal neoplasm. Scrotal exploration revealed a deep reddish tumor superior to the testicle and partially covered at its lateral-inferior aspect by the globus major of the epididymis. The tumor was encapsulated and easily dissected from the neighboring structures. There was no apparent cord of tissue extending proximally along the spermatic cord. The specimen measured 2.5 by 1.5 by 1.0 cm. and on cut section displayed the beefy color of normal spleen (fig. 1). Microscopic examination confirmed the typical histology of spleen. A postoperative scan outlined a normal intra-abdominal spleen. Case 2. T. S., a 17-month-old white male ectromelic infant, had a left scrotal mass (fig. 2). When he was 8 weeks old the diagnosis of left hydrocele had been made but when he was 10 months old the scrotal mass appeared more solid and enlarging. There was no history of maternal drug ingestion and parents and child had normal chromosomal studies. On physical examination there was complete absence of the right lower extremity and rudimentary elements of the remaining 3 appendages. The left scrotal sac contained a bluish, spongy mass which was palpable above and separate from the left testicle and which did not Accepted for publication June 29, 1973. * Requests for reprints: 3003 W. Good Hope Rd., Milwaukee, Wisconsin 53209. 1 Mendez, R. and Morrow, J. W.: J. Urol., 102: 598, 1969. 2 McNamara, J. H.: Pathology, 1: 331, 1969. 3 Venzoni, M., Pecchiai, L. and Monaco, L.: Minerva Chir., 25: 1299, 1970.
transmit light. Laboratory studies including an excretory urogram were normal. Preoperative diagnosis was an organizing hematocele or ectopic splenic tissue. Scrotal exploration revealed a beefy-red kidneyshaped mass within the tunica vaginalis and attached to the head of the epididymis by its own vascular pedicle (fig. 3). The vascular cord extended proximally along the spermatic cord as an easily dissectible separate structure. No inguinal hernia was found. A frozen section was consistent with splenic tissue. The specimen measured 2.6 by 1.5 by 1.3 cm. and was dark red on cut surface. Histologically, the mass was entirely composed of splenic tissue with somewhat enlarged splenic follicles (fig. 4).
FIG. 1. Cut section of splenic nodule CLASSIFICATION
All 58 cases of splenic gonadal fusion have occurred on the left side and the anomaly is more frequent in male subjects. Splenic gonadal fusions have been separated morphologically into 2 distinct groups: the continuous and discontinuous types.• In the continuous type, which has been described in 26 cases and was probably present in our case 2, there is a long cord-like structure which extends from the ectopic splenic mass to attach to the normal spleen. It may be pure fibrous or contain various amounts of splenic tissue. It follows closely the spermatic cord in the inguinal • Putschar, W. G. J. and Manion, W. C.: Amer. J. Path., 32: 15, 1956.
120
ECTOPIC SPLEEN IN SCROTUM
FIG. 2. Case 2. Newborn photograph
FIG. 3. Kidney-shaped splenic nodule with vascular pedicle isolated by Penrose drain. Forceps holds epididymis.
canal but at the internal ring it directly traverses the peritoneal cavity anterior to the intestines as it ascends to its termination at the normal spleen. In the discontinuous type, which was noted in 24 cases and present in our case 1, the encapsulated ectopic spleen is attached to the gonadal structures but is completely discrete and lacks any fibrous or splenic cord-like extension to the normal spleen. EMBRYOLOGY
The specific origin for splenic gonadal fusion remains unclear. Two theories have been proposed to explain the embryologic events. The splenic anlage is consistently visible in the fifth week of embryonic life as a proliferation of the surface peritoneal cells on the left side of the dorsal mesogastrium (greater omentum).' These cells break free and invade the underlying mesenchyme where they differentiate as spleen. As the embryonic gut tube rotates, the splenic anlage is thrown into close proximity with the left urogenital fold, which includes the gonadal mesoderm and mesonephric components. A segment of the mesonephros later becomes the epididymis and the mesonephric duct differentiates as the vas deferens. 5 Arey, L. B.: Developmental Anatomy. A Text-Book and Laboratory Manual of Embryology, 2nd ed. Philadelphia: W. B. Saunders Co., 1931.
Since the gonad begins to shift in a caudal di.rec tion during weeks 8 to 12 of gestation, its attachment with splenic tissue must occur between weeks 5 and 8. Sneath has proposed that slight inflammation cf the apposing peritoneal surfaces over the ridge and spleen could produce an adhesion or partial fusion between the 2 organs (fig. 5). 6 This theory would explain why splenic fusions occur exclusively with the left gonadal-mesonephric structures. During the subsequent caudal tion of the testis, the peritonealized adhesion would lengthen and ultimately develop as the intraperitoneal fibrous or splenic cord as seen the continuous type of fusion. Attenuation of tbe cord produced by tension might conceivably evolve to spontaneous rupture with resultant transforma tion into the discontinuous type of splenic fusion. A purely mechanical cause for rupture is suggested by the peculiar association of ectromelia splenic gonadal fusions. Patten described the appearance at 6 weeks of gestation of mesenchyme concentrations which represent the primordia of the 4 extremitieso 7 During the next 2 weeks rapid development takes place so that by 8 weeks well-molded miniatures represent all the appendages. The simultaneous teratogenic insult which results in peromelus and splenic gonadal fusions remains unexplained but it is noteworthy that the 8 ported cases of concomitant ectromelia occurred only with the continuous type of fusion. reduced activity and mobility of the ectromelic fetus in utero may be a factor in the preservation of the intraperitoneal cord. Sneath's theory has been refuted because, with a fusion of the splenic anlage from the wall of the omental sac to the gonadal ridge, the splenic cord should derive its blood supply from the omen tum. 8 Dissections have shown that the splenic cord is supplied by only the splenic and spermatic vessels. In Von Hochstetter' s case, the presence of 2 small. 'Sneath, W. A.: J. Anat. Physiol., 47: 340, 19130 7 Patten, B. M.: Human Embryology, 2nd ed. New York: Blakiston Co., 1953. • Von Hochstetter, A.: Virchow Arch. f. Path. Anat., 324: 36, 1953.
122
MAY AND BOURNE
FIG. 4. Case 2. Photomicrograph of ectopic spleen demonstrates splenic capsule and splenic follicles SNEATH'S THEORY
Mesonephric Duct
Gonadal Ridge
Stomach
6 WEEK EMBRYO
J:IG. 5. Schematic topographic microsection of 6-week embryo shows transcoelomic route for splenic gonadal
fusion.
pieces of spleen within the ovarian capsule could not be explained solely by an adhesion. Von Hochstetter postulated a retroperitoneal pathway for splenic anlage cells to come in contact with the gonad (fig. 6). The end of the caudal limiting fold, which connects the gonad with an area just medial and cranial to the splenic anlage, in essence represents the medial portion of the left pleuroperitoneal membrane. Thus, the anomaly would be explained by the abnormal appearance of splenic cells, either by misplacement or migration, along the caudal limiting fold. This theory could readily account for the discontinuous type of splenic gonadal fusions, although with misplaced splenic cells in the retroperitoneum one might expect a few cases of right-sided fusions. The latter has never been clinically documented. In order to
explain the continuous intraperitoneal cord, Von Hochstetter postulated a complete detachment of the cord from the retroperitoneal area to rest freely in the peritoneal cavity. Sommer gave credence to this theory because in his case the cord possessed a thin mesentery to the lateral abdominal wall in its entire length." DISCUSSION
Nearly half of the reported cases of splenic gonadal fusion have occurred in children. In order to avoid orchiectomy or epididymectomy, one must be aware of the possibility of ectopic splenic tissue in the scrotal sac. A number of cases were observed at autopsy but we noted 13 cases in which orchiectomy had been performed, often because of • Sommer, J. R.: Pediatrics, 22: 1183, 1958.
123
ECTOPIC SPLEEN IN SCROTUM
VON HOCHSTETTER'S THEORY
End of caudal
Gonadal Ridge Spleen Stomach
5 - 6 WEEK ErvJBRYO FIG. 6. Schematic topographic microsection of 5 to 6-week embryo shows completely retroperitoneal route for splenic gonadal fusion.
misinterpretation of the lesion as neoplasm. Since these splenic nodules are firm or rubbery, do not transmit light and may be poorly delineated from the normal scrotal contents, an operation is mandatory. An astute preoperative diagnosis still requires microscopic confirmation. Therefore, for practical purposes, recognition of a splenic mass at exploration is necessary in order to avoid orchiectomy. A number of clinical points may suggest the correct diagnosis. The lesion always occurs on the left side and may have been present for a long time. It is often associated with an indirect inguinal hernia and occasionally occurs with incomplete descensus of the left testicle. Scrotal spleens are generally located within the tunica vaginalis, are beefy red in color and are separated from the testicle and epididymis by a discrete capsule. Von Hochstetter documented splenic pieces within the ovary and Venzoni and associates found the spleen and testicle grossly fused together, although separate capsules were subsequently identified microscopically. In a few cases multiple splenic nodules have been found. The presence of the continuous cord is an additional hint as to the nature of the lesion. The
robust vascular cord, shown in figure 3, is separable from the normal anatomic structures of the spermatic cord. The suspected benign nature of the tumor can be confirmed by frozen section examination before extirpation. In many cases the excised testicle was described as atrophic or inflamed. In our cases the testicle was of similar size to its contralateral mate on palpation and <>nno,wo normal. Whether these testicles will later normal spermatogenesis is conjectural but should contribute to subsequent endogenous androgen production. There should be little reluctance to remove scrotal spleen since these nodules are truly accessory spleens. A normal intra-abdominal spleen has been invariably confirmed in cases further evaluated by transabdominal exploration, postoperative radioisotope splenograms or in a few cases at autopsy. SUMMARY
Two cases of splenic gonadal fusion are '""'""'''""'r1 The conflicting theories of embryogenesis are discussed. A clinical awareness of ectopic scrotal spleens can obviate inopportune radical scrotal operations, especially in children.