Lesiones inguinales pediátricas: hallazgos radiológicos / Pediatric groin lesions: imaging findings

OBJETIVOS: La región inguinal es un área anatómica compleja que ha sido tradicionalmente olvidada por los radiólogos dado que la mayoría de las lesiones pueden diagnosticarse mediante datos clínicos y con la exploración física. No obstante, cada vez es más frecuente la solicitud de ecografías, bien para confirmar la existencia de patología o para resolver casos dudosos. Por otra parte, la patología inguinal incluye entidades únicas de la edad infantil. El objetivo de este trabajo es describir los hallazgos radiológicos clave de las lesiones inguinales pediátricas, poniendo especial énfasis en los datos ecográficos CONCLUSIONES: El conocimiento de la patología inguinal pediátrica y sus claves en imagen ayudan a mejorar el rendimiento diagnóstico de la ecografía

OBJECTIVES: The groin is a complex anatomic region that has traditionally been ignored by radiologists because most lesions can be diagnosed from clinical data and physical examination. Nevertheless, ultrasound examinations of the groin are increasingly being requested to confirm injury or to resolve diagnostic uncertainty. On the other hand, some conditions involving the groin are found only in pediatric patients. This article describes the key imaging findings in pediatric groin injuries, placing special emphasis on the ultrasound appearance. CONCLUSIONS: Knowledge about conditions that can affect the groin in pediatric patients and the key imaging findings associated with them helps improve the diagnostic performance of ultrasound

Canal of Nuck Abnormalities.

Canal of Nuck abnormalities are underrecognized causes of labial masses with potential adverse outcomes. The 2 main categories of canal of Nuck abnormalities are hernias and hydroceles. There are 3 types of canal of Nuck hydroceles: communicating, encysted, and bilocular. Canal of Nuck hernia contents vary, but those containing ovaries need urgent medical attention because of an increased risk of ischemia. Ultrasound can establish a definite diagnosis in all cases. This article reviews the embryologic characteristics, anatomy, pathologic characteristics, and imaging features of these abnormalities while providing a clear pictorial depiction of various unique hernias and hydroceles seen with this entity.

The pediatric inguinal canal: Systematic review of the embryology and surface anatomy.

The inguinoscrotal region is one of the most common areas operated on in pediatric surgery. Despite this, the surface anatomy of the pediatric inguinal canal is variably defined. The aim of the current systematic review is to evaluate the development and surface anatomy of the pediatric inguinal canal. A systematic review of inguinal canal anatomy in children was conducted using the electronic databases: Medline, PubMed, Scopus, and Google Scholar. Relevant anatomical measurements and relationships were reviewed. The anatomical structures forming the walls of the inguinal canal were identified in fetuses as early as 8-10 weeks gestation. No studies addressed the developmental basis of this early defect in the lower anterior abdominal. Later gonadal development and descent has a defined role. In vivo measurements of children carried out during open surgery are inconsistent. Some studies showed rapid growth velocity of the length of the inguinal canal up to 2 years of age (with height and growth of the bony pelvis) before plateauing, while others suggested no increase in canal length prior to 10 years of age. The position of the deep inguinal ring was equally unclear; some studies suggested this was medial to the midpoint of the inguinal ligament. No studies described the position of the superficial ring, challenging the assumption that the rings are superimposed in the neonate. The dearth of studies analyzing pediatric inguinal anatomy means that changes in the position of the rings with respect to the lengthening of the canal remain unclear.

Clinical case of a patient diagnosed with sinister inguinal hernia and disembriogenesis of the inguinal canal.

Hernia (lat. - rupture, burst) or protrusion represents the act of escape of tissue, organ or an organ constituent through an innate or acquired fault of the muscle or the connective tissue membrane. The inguinal hernia, also known as groin hernia, rates one of the most frequent surgical conditions. It is manifested by all ages, however is more common in males. The inguinal hernia exhibits by the protrusion of abdominal organs or their segments, for instance portions of the small or large intestine, into the inguinal canal. The groin hernias classify into two subtypes--direct and indirect, and also acquired and inherited. Two kind of anomalies exist--anomalies connected with the obliteration of processus vaginalis peritonei and anomalies connected with the embryogenessis of the inguinal canal. We present a clinical case of a 59-years-old male presenting with emerged arch-like protuberance in the sinister groin region, enlarging during physical effort and strain, accompanied by a strong, harsh pain. Intraoperatively it was discovered a disembryogenessis of the inguinal canal, a total lack of the front wall of the canal itself, a lack of formed superficial inguinal opening and inobliterated processus vaginalis peritonei.

Testicular migration chronology: do the right and the left testes migrate at the same time? Analysis of 164 human fetuses.

OBJECTIVE: To determine if the right and the left testes migrate at the same time during the human fetal period. SUBJECTS AND METHODS: We studied 164 human fetuses (328 testes) ranging in age from 12 to 35 weeks post-conception. The fetuses were carefully dissected with the aid of a stereoscopic lens at ×16/25. The abdomen and pelvis were opened to identify and expose the urogenital organs. Testicular position was classified as: (a) Abdominal, when the testis was proximal to the internal ring; (b) Inguinal, when it was found between the internal and external inguinal rings); and (c) Scrotal, when it was inside the scrotum. RESULTS: The testes were abdominal in 71% of the cases, inguinal in 9.41%, and scrotal in 19.81%. There was asymmetry in testicular migration in nine cases (5.5%). In three of these nine cases, one testis was situated in the abdomen and the other in the inguinal canal; in another three one testis was situated in the abdomen and the other in the scrotum, and in the remaining three, one testis was in the inguinal canal and the other in the scrotum. In five of the nine cases of asymmetry, the right testis completed the migration first, but this was not statistically significant. CONCLUSION: Asymmetry in testicular migration is a rare event, accounting for <6% of the cases. The right testis seems to complete migration first.

Imaging of the inguinal canal in children.

The inguinal canal is often seen at the edge of the field of view on plain radiography, computed tomography, or magnetic resonance imaging and may often not be scanned when performing sonography of the scrotum or abdomen. As a result, pathology in this anatomical region may be easily overlooked. The peculiar embryology of the inguinal canal makes the identification of pathology in the inguinal region significant, as some of the processes that take place within the scrotum may originate in the abdomen, and vice versa. This article reviews the relevant embryology of the inguinal canal, discusses abdominal and scrotal conditions that involve the inguinal region, and illustrates associated pathology.

The secondary external inguinal ring and associated fascial planes: surgical anatomy, embryology, applications.

Classically, two inguinal rings are defined: internal and external. We previously introduced a third one, the secondary internal inguinal ring, deep to the classic internal. Here, we present a fourth ring, the secondary external inguinal ring, initially described by McGregor (Surg Gynecol Obstet 49:273-307, 1929), but now forgotten. Embryologically, this ring may be formed by evagination of Scarpa's fascia during testicular descent. Anatomically, it is located 2 cm below the pubic tubercle. It is formed by Scarpa's fascia that covers the spermatic cord anteriorly; medial and lateral fascial reflections delineate the ring and form the spermatic cord canal. The cord is attached to the posterior wall of the canal. The canal ends at the entrance of the scrotum, where Colles' fascia fuses with coverings of the cord. Adjoining the secondary external ring, at the same surgical layer and communicating with the subcutaneous abdominal space, are four subcutaneous pouches: laterally, the superficial inguinal pouch; medially, the perineal, femoral, and pubic pouches. Surgically, an inguinoscrotal hernia passes though the secondary external ring and obtains an extra outer layer by entering the spermatic cord canal. Underdevelopment of the ring leads to incomplete testicular descent or ectopic testis. We recommend reconstruction of Scarpa's ring after orcheopexies and herniotomies in children. After urethral rupture distal to the urogenital diaphragm, urine may fill the subcutaneous abdominal space, pouches, and scrotum, due to their communication around the secondary external ring. In females, this ring was not found, possibly because of the non-descent of the ovaries through (and beyond) the inguinal canal.

The female gubernaculum: role in the embryology and development of the genital tract and in the possible genesis of malformations.

The female gubernaculum is an embryonic structure that gives rise to the uterine round ligament and seems to be important in Müllerian development. In the absence of androgens and anti-Müllerian hormone, the paramesonephric or Müllerian ducts complete their invagination and development, interfering with the connection of the tissue column that begins at the inguinal cone (the gubernaculum) and targets the mesonephric duct and caudal ligament of the gonad. The gubernaculum then grows over the Müllerian ducts, incorporating its muscular fibres. Outside and above this point, the Müllerian ducts give rise to the Fallopian tubes, whereas medially to the point of insertion of the gubernaculum, the Müllerian ducts develop into the normal uterus, the adequate formation of which is also induced by the mesonephric ducts. Diverse human anatomical and physiological characteristics such as the simplex uterus, as well as pathological conditions and certain female genital malformations, could be related to gubernaculum dysfunction. The main conclusions in this article are: (1) The female gubernaculum is the origin of the uterine round ligament but probably not of the uteroovarian ligament. Gubernacula are composed of muscular fibres that probably derive from the abdominal wall and that, when fixed and fused with the Müllerian ducts, allow or induce, together with the mesonephric ducts, the adequate development and formation of the uterus. (2) The female gubernaculum seems to be responsible for many of the specific human characteristics of Müllerian development, including the uterus simplex, the anteflexion and low intra-abdominal position of the uterus, and the disposition of uterine muscular fibres. (3) The female gubernaculum seems to be related to pathologies arising from the round ligaments and inguinal hernia. Likewise, certain uterine malformations (e.g., didelphys uterus, Rokitansky syndrome) and accessory and cavitated uterine masses might be related to gubernaculum dysfunction.

Cremaster muscle myogenesis in the tip of the rat gubernaculum supports active gubernacular elongation during inguinoscrotal testicular descent.

PURPOSE: Cryptorchidism is a common abnormality and normal testicular descent is controlled by the gubernaculum. The cremaster may originate from abdominal muscles during gubernacular eversion or alternatively it may develop inside the gubernaculum. We studied cremaster myogenesis to determine how it develops. MATERIALS AND METHODS: Coronal sections of the pelvis were prepared from male Sprague-Dawley® rats and from males treated prenatally with the antiandrogen flutamide at embryonic day 19, and postnatal days 10, 19 and 35 after receiving ethical approval. Immunohistochemical stains were prepared for Ki67, Pax-7, myogenin, myosin heavy chain 7, Myh1, Myh2, Myh4, embryonic myosin, and slow and cardiac troponin T. Cell counts of the 1) gubernacular tip, 2) proximal gubernaculum/cremaster muscle and 3) adjacent abdominal wall are shown as a percent of positive fibers or positive cells per area. RESULTS: Throughout embryonic day 19, and postnatal days 10 and 19 proliferation (Ki67) was maximal at the gubernacular tip (p <0.001), as were muscle stem cells markers (Pax-7 p <0.05), early myogenesis (myogenin p <0.001) and immature muscle (Myh7, and slow and cardiac troponin T p <0.0001). In contrast, secondary (fast twitch, Myh1, 2 and 4) fibers were more common in abdominal muscles (p <0.0001). Differences in muscle maturity and composition decreased with time. Flutamide treated rats showed more cellular proliferation than controls postnatally on postnatal day 10 (p <0.001) as well as persistent immature embryonic myosin at the tip from postnatal day 19 (p <0.05). CONCLUSIONS: Results show that the rat cremaster muscle is more immature at the gubernacular tip, consistent with myogenesis occurring in the gubernaculum during migration to the scrotum, as proposed in humans.

Embryology of the testicular descent.

Numerous researchers studied the morphology of the testicular descent, including the possible function of the gubernaculum. However, a clear illustration of this process is still missing. The aim of this paper was to illustrate the embryology of the testicular descent in the rat by scanning electron microscopy. In a first phase of the intra-abdominal testicular descent, the testis moves actively from the lower pole of the kidney towards the bladder neck. In a second inguinal phase the testis enters groin and moves in the developing processus vaginalis peritonei caused by the disappearance of the bulb of the gubernaculums testis.

Development of the gubernaculum during testicular descent in the rat.

Gubernacular elongation during inguinoscrotal testicular descent and cremaster muscle development remains poorly described in mammals. The role of the genitofemoral nerve (GFN) remains elusive. We performed detailed histological analysis of testicular descent in normal rats to provide a comprehensive anatomical description for molecular studies. Fetuses and neonatal male offspring (5-10 per group) from time-mated Sprague-Dawley dams (embryonic days 15, 16, and 19; postnatal days 0, 2, and 8) were prepared for histology. Immunohistochemistry was performed for nerves (Class III tubulin, Tuj1) and muscle (desmin). At embryonic days 15 and 16, the gubernaculum and breast bud are adjacent and both supplied by the GFN. By embryonic day 19, the breast bud has regressed and the gubernacular swelling reaction is completed. Postnatally, the gubernacular core regresses, except for a cranial proliferative zone. The cremaster is continuous with internal oblique and transversus abdominis. By postnatal day 2 (P2), the gubernaculum has everted, locating the proliferative zone caudally and the residual mesenchymal core externally. Eversion creates the processus vaginalis, with the everted gubernaculum loose in subcutaneous tissue but still remote from the scrotum. By P8, the gubernaculum has nearly reached the scrotum with fibrous connections attaching the gubernaculum to the scrotal skin. A direct link between GFN, gubernaculum, and breast bud suggests that the latter may be involved in gubernacular development. Second, the cremaster muscle is continuous with abdominal wall muscles, but most of its growth occurs in the distal gubernacular tip. Finally, gubernacular eversion at birth brings the cranial proliferative zone to the external distal tip, enabling gubernacular elongation similar to a limb bud.

The common fetal development of the mammary fat pad and gubernaculum.

BACKGROUND/AIMS: Recent work both from our laboratory and in marsupial models of testicular descent suggests a strong connection between the mammary line and gubernacular migration. This study investigated the relationship between the mammary fat pad (MFP) that underlies the mammary line and the developing gubernaculum by fluorescent immunohistochemistry. METHODS: Rats at E17 and E19 were fixed and processed for immunohistochemistry. Sagittal sections of male fetuses were stained with antibodies against androgen receptor (AR), prolyl-4 hydroxylase ß, Desmin, activated Notch-1, Jagged-1, and Ki-67. These were analyzed by fluorescent confocal microscopy. RESULTS: At E17 and E19, the MFP anlage forms a continuous distribution of fibroblasts passing immediately adjacent the gubernaculum to the future scrotum. Within this exists a distinct subpopulation of fibroblasts expressing AR distributed over the path of inguinoscrotal descent of the gubernaculum. Proliferation and Notch-1 signaling were similar throughout the MFP with differential Notch-1 signaling in the E19 gubernaculum. CONCLUSION: This investigation has identified the presence of a distinct AR-expressing subpopulation of MFP fibroblasts over the path of inguinoscrotal descent during the key androgenic programming window of this phase. This unique developmental pattern is consistent with a prime role for the MFP in testicular descent.

Hidden in plain sight: the mammary line in males may be the missing link regulating inguinoscrotal testicular descent.

BACKGROUND/PURPOSE: Inguinoscrotal testicular descent is controlled by androgens and the genitofemoral nerve, but the trigger for what makes the gubernaculum become a migratory organ like a limb bud remains unknown. Recent observations in the flutamide-treated rat suggested a link with the mammary line. We aimed, therefore, to reassess histologic anatomy in 2 different rodent models of androgen blockade, the testicular feminisation mouse (TFM) and the flutamide-treated rat. METHODS: Neonatal TFM mice and fetal and neonatal rats after pretreatment of dams with an antiandrogen, flutamide (75 mg/kg; sunflower oil; days 16-19), were prepared for histologic analysis of the inguinal region and compared with fetal and neonatal controls. RESULTS: Fetal control rats (E15.5 days) showed a mammary bud just outside the future inguinal canal adjacent to the gubernaculum. Neonatal TFM mice showed persistence of the inguinal breast bud supplied by the genitofemoral nerve. Flutamide-treated rats (D2) showed the gubernaculum surrounded by a persisting breast bud. CONCLUSIONS: The inguinal mammary line is adjacent to the gubernaculum in fetal rodents, and after androgen blockade, the gubernaculum becomes connected to the breast. The male mammary line, which is hidden in plain sight outside the inguinal canal, is made visible by androgen blockade. It may be the missing link in testicular descent, regulating gubernacular migration.

The antiandrogen flutamide perturbs inguinoscrotal testicular descent in the rat and suggests a link with mammary development.

AIM: Inadequate androgen activity is a likely cause of cryptorchidism in humans, affecting inguinoscrotal testicular descent. Flutamide, a nonsteroidal antiandrogen, produces cryptorchidism in rats. We aimed to determine the anatomical and histologic effects of flutamide. METHODS: Time-mated Sprague-Dawley female rats were injected subcutaneously with flutamide (75 mg/kg in sunflower oil) on days 16 to 19 of pregnancy. Embryonic (E) and postnatal (P) male offspring were collected (E16, E19, P0, P2, P4, P8) in control and flutamide-treated groups (n = 5-10). Samples were fixed in 4% paraformaldehyde. Five-micrometer-thick sections were prepared for hematoxylin and eosin, trichrome and immunohistochemical stains (Desmin, TuJ1, Ki67). This identified muscle and neural cells and areas of cell proliferation. RESULTS: Postnatally, the gubernaculum in flutamide-treated rats had more mesenchyme and muscle than controls. Gubernacular eversion failed, and mammary tissue persisted around the gubernaculum in flutamide-treated rats. Flutamide had no effect on embryonic gubernacular anatomy and histology. CONCLUSIONS: Prenatal androgens altered postnatal gubernacular anatomy and histology in the postnatal period. Our findings indicate that the failure of gubernacular differentiation and migration may be because of the ongoing presence of mammary tissue in the region of the external inguinal ring.

Inguinal canal development: the muscular wall and the role of the gubernaculum.

The inguinal canal is an anatomically complex region. Although much has been written about the gubernaculum and the descent of the testis, little is known about the development of the abdominal wall itself. We dissected this inguinal canal in 75 fetuses between 10 and 25 weeks of gestation, 42 males and 33 females. We identified the anterior body-wall muscular layers, located the gonads and uterus, and observed the formation of the scrotum. The gubernaculum was dissected, from the deep to the superficial ends and its distal attachments were determined. We proved that the muscular-fibrous layers of the wall were well-differentiated and observed how the inguinal canal enlarged with embryological development. In only one of the cases, an abnormal testis was found located in the scrotum. The upper end of the gubernaculum inserted into the inferior pole of the testis or the lateral angle of the uterus, according to gender. The lower end was attached by one or multiple tails, mainly on the pubic bone. This fact explained the clinical findings of ectopic testis. Observations of the abdominal wall and its relationship with the gubernaculum assisted us in explaining the development of the inguinal region, the formation of the inguinal canal, and the presence of the gubernaculum, in both genders. We intend to explain how the deep inguinal ring moves upwards, bringing the gubernaculum along with it, and thus determines the final form of the inguinal canal.

Factors controlling testis descent.

Descent of the testis from an intra-abdominal site in foetal life to an extracorporeal location after birth is a mandatory developmental process to ensure that the mature testis promotes normal spermatogenesis. The two phases of transabdominal and inguinoscrotal descent occur approximately during the first and last thirds of gestation respectively. Key anatomical events to release the testis from its urogenital ridge location and to guide the free gonad into the scrotum are the degeneration of the cranio-suspensory ligament and a thickening of the gubernaculum. Androgens play a role in both these processes, particularly with respect to enabling the testis to traverse the inguinal canal in the final phase of descent. Experiments in animals suggest that androgens mediate this effect via the release of calcitonin gene-related peptide by the genitofemoral nerve, but direct evidence for such a mechanism is lacking in humans. The transabdominal phase of descent is under the control of insulin-like 3 (INSL3), a product of the Leydig cells. Definitive evidence of its role in rodent testis descent is illustrated by the phenotype of bilateral cryptorchidism in Insl3-/- null mice. Circulating levels of INSL3 are higher in boys at puberty, are undetectable in girls and are lower in boys with undescended testes. A minority also have a mutation either in the INSL3 gene or affecting its receptor gene, relaxin/insulin-like family peptide receptor 2 (LGRF8). Other factors that may play a role in testis descent include the anti-Mullerian hormone and members of the HOX gene family. Evidence that the prevalence of undescended testis may be increasing provides a phenotypic readout for the effects of postulated chemicals in the environment interfering in some way with the action of factors that control testis descent. Epidemiological studies point to profound geographical variations in prevalence in countries such as Denmark and Finland. Associations have been found with levels of chemicals labelled as endocrine disruptors being higher in breast milk samples from mothers with cryptorchid boys when compared with controls. The adverse effects of these compounds (e.g. bisphenol A) can be replicated in the offspring of dams exposed during pregnancy. A sensitive marker of an anti-androgen effect of a compound is a reduction in the anogenital distance, an anthropometric measurement that is significantly greater in males compared with females. The observation of an association between the anogenital distance in infant boys and the level of pesticides in the urine of their mothers in late gestation indicates that this has the potential to be a useful surrogate marker of the effects of environmental chemicals on testis descent in human population studies. The rightful place for the testis at birth is in the scrotum in order to provide the temperature differential essential for normal spermatogenesis. Appropriate screening programmes and early surgical intervention are the prerequisites to ensure optimal fertility in adulthood and a considerably lessened risk of testis cancer.

Fetal development of the human gubernaculum with special reference to the fasciae and muscles around it.

Previous descriptions of human gubernacular embryology failed to follow some basic developmental processes, and surgically relevant structures, such as the iliopubic tract, had not been discussed relative to gubernacular development. We addressed these shortcomings in this study that examined two stage-groups of human fetuses. At 8-12 weeks of gestation, the gubernaculum arose from the mesonephric fold at or near the gonad. Gubernacular mesenchyme communicated with the subcutaneous tissue via a narrow slit in the rectus aponeurosis. The inguinal fold, containing the inferior epigastric vessels, was separated from the gubernaculum. At 20-25 weeks of gestation, the gubernaculum connected to the testis or uterus. When the testis successfully descended to a peritoneal recess on the lateral side of the umbilical artery, the gubernaculum connected to the testis free of interference by the thick artery and its associated peritoneal fold. This may explain the known asymmetry in testicular descent. The inguinal canal was enclosed by a sheet-like aponeurosis: its ventromedial part was composed of the rectus sheath and the external oblique aponeurosis, whereas the dorsolateral part consisted of a thick aponeurosis covering or facing the iliopsoas. The former (latter) aponeurosis seemed to develop into the inguinal ligament (the iliopubic tract) in adults. According to the topohistology of the muscles associated with the interfoveolar ligament, we identified muscle fragments around the gubernaculum as derivatives of the transversus and/or internal oblique. Consequently, the inguinal canal contained the cremaster proper developing within the gubernaculum and parts of the abdominal wall muscles mechanically incorporated into the canal.

The migrating gubernaculum grows like a "limb bud".

BACKGROUND: The gubernaculum is crucial for testicular descent, and in the second, or inguinoscrotal, phase of descent it has no caudal attachments. Cranially, it is attached to the testis, but its caudal free tip migrates to the scrotum controlled by the genitofemoral nerve. Recent studies show active proliferation in the tip. We hypothesized that the gubernacular tip may grow like a limb bud. METHODS: We performed whole-mount in situ hybridization studies on male and female fetal mice (ages, E14.5-E18.5; n = 162) looking for limb bud regulatory factors. RESULTS: Our results showed that a member of the fibroblast growth factor (Fgf) family, Fgf10, and Hoxa10 were both expressed in the male gubernaculum at E14.5, and Hoxa10 was also expressed in the E16.5 mice. Weak staining was seen in the female gubernaculum for Hoxa10 on days E14.5 and E16.5, whereas no staining for Fgf10 was seen in the female gubernaculums. CONCLUSIONS: These studies, although preliminary, suggest limb bud regulators are essential for gubernacular growth. Hox genes and Fgfs may be fruitful areas of research to unravel the molecular control of gubernacular migration during testicular descent.