Discussion
The development of testes and their descent from abdomen to scrotum pass through complex stages, it begins from 7th week of gestation and usually completed at 35th week. Several androgenic hormones and certain mechanical factors control the normal migration of the testis.10 It has been proposed that calcitonin gene-related peptide (CGRP) liberated from the genitofemoral nerve will provide a chemical gradient and hence indirectly promote growth of the gubernacular tip leading to its movement and progress in the right direction toward the scrotum.11 Normally, the testis follows the course of scrotal extension of gubernaculum and any disturbance in this process leads to maldescent. The testis that is stopped at some point within its normal pathway is true undescended testis while the testis that follows one of the other tails of the gubernaculum to an aberrant pathway is termed ectopic testis. Another rare congenital anomaly that must be kept in mind as a cause of undescended testis is splenogonadal fusion, especially when there is unusual scrotal mass or when there are associated anomalies.12
In spite of the several suggested theories trying to explain the occurrence of testicular ectopia, its clear etiology remains unknown. These theories focused on different concepts like gubernacular abnormalities, genitofemoral nerve disorders, endocrine disorders and intra-abdominal pressure.13 The ‘Tails hypothesis of Lockwood’ is the most famous one, he suggested that there are several tails of insertions extended from inferior gubernaculum so the normal descent will lead to scrotal insertion as dominant one. If the other insertions are more potent and larger during the transinguinal phase of testicular descent, the testis will be dragged in wrong direction and lodged in an aberrant location to be ectopic.14 15
Hutson suggested that abnormal position of genitofemoral nerve leads to an abnormal movement of the gubernaculum and pushes the testis to abnormal position.10 The chemotactic gradient resulted from hormone imbalance between androgen and CGRP released by the genitofemoral nerve play important role in testicular descent as it acts as a guide to gubernacular progress.4 16 On the other hand, Middleton et al17 suggested that the normal descent of gubernaculum is facilitated by increased intra-abdominal pressure and in case of inadequate pressure there will be testicular ectopia.17 18
Various hypotheses have been proposed to clarify the development of TTE,17 Berg proposed that both testes develop from the ‘same germinal ridge’.19 Kimura accepted that if the two vasa deferentia emerged from one side, there had been one-side root of origin however on the off chance that there were two-sided origins, one testis will be crossed over.20 Gupta proposed that during early development there is cohesion and coalition of Wolffian ducts and that descent of one testis made the 2subsequent one pursue.21 Frey also noticed that TTE might be due to defect in gubernacular development on the ipsilateral side.22 Indeed, the pathogenesis of TTE still stays misty.
Ectopic testis can be found at five different sites, these are femoral canal, suprapubic region, perineum, opposite side of the scrotum and anterior abdominal wall.3 4 Some authors include the superficial inguinal pouch (Denis Browne pouch) as a site of ectopic testis (about 75% cases of testicular ectopia),20 but others put it under the name of undescended variant, as they notice that a testis located at the superficial inguinal pouch behaves as a true cryptorchid testis regarding histological changes and response to hormonal therapy.6
Perineal
Ectopic testis is seen very rarely in pediatric surgical practice with approximately 175 reported cases in the literature, the majority of these cases are unilateral.21 We encountered two cases of perineal testis out of five reported cases of ectopic testis, both were on the left side, so the palpable soft tissue mass in perineum on the same side of an empty hemiscrotum perineum is very suggestive of ectopic testis. Surgical exploration for perineal ectopic testes is usually done through inguinal approach as a standard but some surgeons prefer low scrotal approach. The hernia sac was not identified in our patient and we found that gubernaculum is fixed to the perineum so the testes are placed in ipsilateral hemiscrotum easily without retroperitoneal dissection because of adequate length of the testicular vessels and vas deferens.
The anterior abdominal wall is exceptionally variant site for ectopic testis. The deviation of a testis from its typical course of descent to a location in the anterior abdominal wall cannot be clarified on embryological basis,23 it might be because of entrapment of a testis in spigelian hernia, or because of neonatal omphalitis that compellingly pulled the testis upward during ensuing healing.24 True undescended testis is commonly associated with indirect inguinal hernia, the same thing is noticed with ectopic testis. Siddiqui et al15 and Haseeb et al16 reported the association of anterior abdominal wall testes with ipsilateral inguinal hernia in their cases, during their open groin exploration they found that the testes were migrating between fat planes and muscles of the abdominal wall so they performed herniotomy with subdartos orchiopexy. Nevertheless, Yeap et al25 reported a case of abdominal ectopic testis without any hernia, similarly in our case report 1, there was no association of hernia with ectopic testis.
Since the first description of TTE by Lenhossek in 1886 until 2008, >100 cases have been reported in literature as claimed by Naouar et al. There are three types of TTE according to the presence of associated anomalies:
Type I (50%) associated with inguinal hernia.
Type II (30%) associated with persistent or rudimentary Müllerian duct structures.
Type III (20%) associated with other disorders (inguinal hernia, hypospadias, pseudo-hermaphroditism and scrotal abnormalities).
Patients with TTE usually present with right ectopic testis with clinical signs of inguinal hernia on contralateral side or sometimes present with incarcerated hernia.5 26 The diagnosis of such case is usually made during exploration for inguinal hernia and it is very difficult to made preoperatively. Nevertheless, some articles stated that it can be diagnosed preoperatively by ultrasonography of an experienced sinologist or by CT and MRI.27 28 In this paper, we presented intraoperative diagnosis of TTE on left side (case report 4) after trial of unsuccessful manual reduction for incarcerated left inguinal hernia (type I TTE). Vascular structures and vas deferens of the testicles might be separated or united; TTE associated with fused vas deferens is extremely rare. This condition may prevent the testis from being placed into the scrotum easily during orchiopexy.29 There were two options for management of TTE; either extraperitoneal orchiopexy or trans-septal orchiopexy,30 which is recommended in case of fused vas deferens like our case when we traversed the testis across the scrotal septum and fixed in the proper contralateral side. While in the extraperitoneal approach, the testis is released from its surroundings and passed near root of penis to be located in the contralateral hemiscrotum.
Ideally speaking, when two gonads have been encountered on one side during inguinal surgery, complete evaluation of abdominal structures should be performed through diagnostic laparoscopy or mini laparotomy for detection of Müllerian structures and any associated congenital genitourinary abnormalities, a biopsy should be taken from gonads or any tissue remnants.
In spite of the fact that patients with TTE are at expanded danger of threatening histological changes and malignant transformation like seminoma, embryonal carcinoma, teratoma and yolk sac tumor,31 there is no reported case of malignancy arising from the retained associated Müllerian structures, and the absence of Mullerian inhibitary factor (MIF) does not seem to be additional risk factor of testicular malignancy. Therefore, hysterectomy is not indicated routinely for every patient with TTE and obvious retained Müllerian structures as excision of structures will add risk of extra injury.32
Although an ectopic testis is uncommon condition in pediatric surgical practice, it should not be disregarded in cases of void scrotum. Appropriate clinical examination should be done in warm and relaxed surroundings beginning by putting one finger on each side of scrotum neck to prevent the testes from being withdrawn out of the scrotum. Each side of the scrotum is then palpated for presence of testis; in case that is not there, the fingertips are put just medial to the anterior superior iliac spine and moved firmly toward the pubic tubercle where the other hand holds back to catch the testis if it shows up.
The ectopic location of the testes make them vulnerable to a number of complications like trauma, torsion, infertility and malignancy. The association of ectopic testis with a contralateral undescended testis (as in our case report 5) suggests that ectopic and undescended testes are variants of the same congenital anomaly, having the same pathological findings with increased incidence of subfertility and testicular malignancy.3 Although the complications of ectopic testes are the same as for undescended testes, the timing of surgery should be different; there is no need to delay surgery in ectopic testis and surgery is indicated even if there is no hernia present. Any attempt to move the ectopic testes into the scrotum with hormone therapy have been found to be ineffective.20