Urorectal septum malformation sequence: Insights into pathogenesis

Urorectal Septum Malformation Sequence With Retroperitoneal Neuroblastoma: A Case Report of an Unusual Association

Urorectal septum malformation sequence (URSMS) is an uncommon disease characterized by a failure of the anorectal septum to divide the cloaca and fuse with the cloacal membrane. Complete URSMS is usually lethal in newborn due to severe renal dysfunction and pulmonary hypoplasia. Partial URSMS is compatible with life with a single perineal opening draining a common cloaca with an imperforate anus which amenable to surgical management. Antenatal diagnosis of URSMS is challenging because of multisystem, complex abnormalities involving gastrointestinal, urogenital tract, cardiovascular, and musculoskeletal systems. In this case report, we describe a 15-week male fetus with partial URSMS having a spectrum of multisystem structural anomalies associated with fetal neuroblastoma in retroperitoneal location and adrenal neuroblastoma in situ.

Male pseudohermaphroditism in a complex malformed calf born with an acardius amorphus cotwin-a case report

BACKGROUND

Male pseudohermaphroditism is a developmental anomaly wherein animals are genetically and gonadally male, but their internal and/or external genitalia resemble those of females. In cattle, pseudohermaphroditism is often accompanied by multiple severe malformations. To the best of our knowledge, this is the first report of male pseudohermaphroditism in a complex malformed calf born with an acardius amorphous cotwin.

CASE PRESENTATION

This report describes the case of a three-day-old, male anurous Japanese Black calf born with an acardius amorphous cotwin, complete absence of the tail, agenesis of the anus, separate scrota, and umbilical hernia. Transthoracic echocardiography and computed tomography revealed serious malformations in the skeletal system and the circulatory, digestive, urinary, and genital organs. Necropsy revealed rectal atresia, immature testes, epididymis, and penis, but no male accessory gonads. Histological analyses revealed vaginal- and uterine-like tissues adjacent to or fused to the rectum. Fluorescence in situ hybridization detected X and Y chromosomes, and some cells presented two X-probe signals in the same nucleus.

CONCLUSIONS

In contrast to the male genitalia, the female genitalia derived from the Müllerian ducts were difficult to detect by necropsy in the presented case. Many similar cases may be overlooked in clinical practice.

Gastrulation : Current Concepts and Implications for Spinal Malformations

It has been recognised for over a century that the events of gastrulation are fundamental in determining, not only the development of the neuraxis but the organisation of the entire primitive embryo. Until recently our understanding of gastrulation was based on detailed histological analysis in animal models and relatively rare human tissue preparations from aborted fetuses. Such studies resulted in a model of gastrulation that neurosurgeons have subsequently used as a means of trying to explain some of the congenital anomalies of caudal spinal cord and vertebral development that present in paediatric neurosurgical practice. Recent advances in developmental biology, in particular cellular biology and molecular genetics have offered new insights into very early development. Understanding the processes that underlie cellular interactions, gene expression and activation/inhibition of signalling pathways has changed the way embryologists view gastrulation and this has led to a shift in emphasis from the ‘descriptive and morphological’ to the ‘mechanistic and functional’. Unfortunately, thus far it has proved difficult to translate this improved knowledge of normal development, typically derived from non-human models, into an understanding of the mechanisms underlying human malformations such as the spinal dysraphisms and anomalies of caudal development. A paediatric neurosurgeons perspective of current concepts in gastrulation is presented along with a critical review of the current hypotheses of human malformations that have been attributed to disorders of this stage of embryogenesis.

The spectrum of cloacal malformations: how to differentiate each entity prenatally with fetal MRI

The term cloacal malformation is commonly used to describe the classic cloacal malformation where there is a single common urogenital and intestinal channel located at the expected site of the urethra. There is, however, a spectrum of cloacal abnormalities that differ from this classic type and are less well discussed in the radiologic and surgical literature. The aim of this pictorial essay is to familiarize radiologists with the anatomy, appropriate terminology and key prenatal imaging findings that differentiate the six entities that constitute the spectrum of cloacal abnormalities.

The Mullerian Black Box: Predicting and defining Mullerian anatomy in patients with cloacal abnormalities and the need for longitudinal assessment

INTRODUCTION

Most patients with a cloacal malformation have a Mullerian anomaly. We sought to examine our patients with a cloacal malformation to determine the proportion of them we felt we knew their Mullerian anatomy and which proportion we felt would most benefit from longitudinal assessment to define their anatomy, reproductive potential, and risk of outflow tract obstruction after puberty. We also compared the preoperative assessment of reproductive anatomy (pelvic ultrasound, MRI, cloacagram, and vaginoscopy) and intra-operative abdominal findings (at the time of primary cloacal reconstruction or subsequent abdominal procedures) to see how these correlated with and which preoperative assessment tool was most predictive of intraoperative anatomy. We also sought to confirm what we expected to be a lack of ovarian pathology.

METHODS

A single site retrospective chart review was performed on all patients with a cloacal anomaly seen between May 2014 and September 2017. Preoperative assessment (pelvic ultrasound, MRI, cloaca gram, and vaginoscopy) and operative reports (both primary reconstruction and later abdominal procedures) were reviewed to ascertain Mullerian and ovarian anatomy.

RESULTS

30 of 36 (83%) of patients had defined Mullerian anatomy after preoperative assessment (pelvic ultrasound, MRI, cloacagram, and vaginoscopy) with or without the addition intraoperative assessment of Mullerian structures obtained during laparoscopy or laparotomy. 19/30 (63%) had duplication of their Mullerian structures. 25/36 (69%) had intraoperative assessment of Mullerian anatomy during laparoscopy or laparotomy. In this group, preoperative assessment with pelvic ultrasound correlated in 4/8 patients (50%), MRI correlated in 3/4 patients (75%), cloacagram in 10/15 patients (67%), and vaginoscopy in 23/25 patients (92%). 14/36 (39%) patients were found to require longitudinal assessment to define anatomy, reproductive potential or risk of outflow tract obstruction after puberty. Patients with ovarian findings described at the time of laparoscopy or laparotomy had no evidence of ovarian pathology.

CONCLUSIONS

The majority of patients with cloaca in our series (83%) had their Mullerian anatomy defined by either preoperative assessment and/or findings at the time of laparoscopy or laparotomy. Duplication of the vagina and uterus was the most commonly described Mullerian anatomy (63%) in our series. Vaginoscopy appears to be superior to pelvic ultrasound, MRI, and cloacagram in predicting Mullerian anatomy. Fourteen of our 36 (39%) patients will require longitudinal assessment follow for reproductive potential and/or risk of outflow tract obstruction after puberty as their Mullerian anatomy is not known. There was no evidence of ovarian pathology in any cloaca patient. While we felt as though we could define Mullerian anatomy in most of our patients, any opportunity for intraoperative assessment of Mullerian anatomy should be utilized and therefore teams who are involved in the management of these patients must have a systematic and collaborative method established to ensure that Mullerian structures are thoroughly evaluated intra-operatively and documented in a standardized fashion.

TYPE OF STUDY

Retrospective Chart review.

LEVEL OF EVIDENCE

III.

Ziracin-Induced Congenital Urogenital Malformations in Female Rats

Spontaneous hypospadias is seldom observed in rats in contrast to its occurrence in 1 out of 250 human births. Ziracin, an antibacterial of the everninomycin class under development for serious enterococcal, staphylococcal, and streptococcal infections, caused anomalies of the external genitalia in F1 female rats and decreased reproductive performance. To characterize the urogenital malformations and determine the period of sensitivity to the effects of Ziracin during development, pregnant rats (F0) were administered 60 mg/kg IV of Ziracin from GD6 to LD21, GD6 to 13, GD14 to the last day of gestation or LD0 to 21. Controls received saline or placebo from GD6 to LD21. Ziracin-induced changes occurred in F1 rats exposed from GD6 to LD21 and GD14 to the last day of gestation, indicating that the period of sensitivity to Ziracin was from GD 14 to the last day of gestation. The urogenital abnormalities consisted of cranial displacement of the urethral opening within the vagina from its normal location at the tip of the genital tubercle. When the urethrovaginal junction occurred at the distal third of the vagina, it created an urogenital cloaca. As a result, ascending infections were seen in the urinary and genital tract. No differences in survivability, body weight, and date of vaginal opening were observed in F1 females. The estrous cycles were slightly prolonged. The mating and fertility indices were decreased as a result of the urogenital anomalies. The mammary glands of pregnant F1 females were underdeveloped, thus F2 pups from affected F1 females had a decreased survival rate. Although the cause of these effects is not known, the findings are consistent with a potential hormonal mechanism.

Complete Diphallia, Imperforate Ani (Type 2 Atresia Ani), and an Accessory Scrotum in a 5-Day-Old Calf

A 5-day-old Angus calf was submitted to the necropsy service at the University of Kentucky Livestock Disease Diagnostic Center. At birth, the calf was noted to have 2 scrota. Five days post-calving the calf developed severe tenesmus and an umbilical infection. Clinical examination revealed atresia ani. At necropsy, complete diphallus, imperforate ani (type 2 atresia ani), and remnants of 2 scrota were identified. This report describes the gross pathologic appearance of a rare case of complete diphallia, imperforate ani (type 2 atresia ani), and an accessory scrotum in a 5-day-old calf.

Spectrum of urorectal septum malformation sequence

Urorectal septum malformation sequence (URSMS) is a rare spectrum of malformations involving various organ systems. Here, we present eight cases of URSMS, noted in autopsy, with different degrees of complexity, seven being the complete type and one being the partial type. All cases had gastrointestinal tract malformation in the form of the imperforate anus and indeterminate genitalia. Other gastrointestinal tract anomalies were anal agenesis in two cases, anorectal agenesis in two cases, and malformed lower intestinal tract in four cases. The associated renal abnormality was noted in five cases, which were unilateral renal agenesis, dysplastic kidney, hydronephrosis, horseshoe kidney, and unilateral hypoplastic ectopic kidney. External genital malformation, present in both male and female fetuses, included a knob-like structure at perineum in female fetuses, genital fold hypoplasia and penile aplasia or hypoplasia in male fetuses. Skeletal abnormalities included two cases of sacral agenesis and one case of lumbosacral dysraphism. Other anomalies included a case with alobar holoprosencephaly, truncus arteriosus with hypoplastic lungs in one case, and three cases with abdominal wall defects. It is our attempt to delineate a spectrum of abnormalities associated with URSMS.

Partial urorectal septum malformation sequence in a kitten with disorder of sexual development

A 2-month-old kitten exhibited simultaneously an imperforate anus, hypospadias, rectourethral fistula and genital dysgenesis (penis restricted to the glans, absence of prepuce and bifid scrotum). Surgical correction consisted of separation of the urinary and digestive tracts, perineal urethrostomy and connection of the rectum to the newly made anal opening. Pathological examination of the testes, conventionally removed at 9 months of age, showed no mature spermatozoa and underdevelopment of germ and Leydig cells. In humans, the absence of an anal opening in association with abnormal sexual development defines the urorectal septum malformation sequence. Here, we describe the first case of this syndrome in a kitten with a normal male karyotype (38,XY) and a normal coding sequence for the SRY gene. Both the rectourethral fistula and observed genital abnormalities might have been induced by a disturbance in the hedgehog signalling pathway. However, although four polymorphic sites were identified by DHH gene sequencing, none cosegregated with the malformation.

The Great Divide: Understanding Cloacal Septation, Malformation, and Implications for Surgeons

The anorectal and urogenital systems arise from a common embryonic structure termed cloaca. Subsequent development leads to the division/septation of the cloaca into the urethra, urinary bladder, vagina, anal canal, and rectum. Defective cloacal development and the resulting anorectal and urogenital malformations are some of the most severe congenital anomalies encountered in children. In the most severe form in females, the rectum, vagina, and urethra fail to develop separately and drain via a single common channel known as a cloaca into the perineum. In this review, we summarize our current knowledge of embryonic cloaca development and malformation, and compare them to what has already been described in the literature. We describe the use of mouse models of cloaca malformation to understand which signaling pathways and cellular mechanisms are involved in the process of normal cloaca development. We also discuss the embryological correlation of the epithelial and stromal histology found in step sections of the common channel in 14 human cloaca malformations. Finally, we highlight the significance of these findings, compare them to prior studies, and discuss their implications for the pediatric surgeons. Understanding and identifying the molecular basis for cloaca malformation could provide foundation for tissue engineering efforts that in the future would reflect better surgical reconstruction and improved quality of life for patients.

Associations of anorectal malformations and related syndromes

Anorectal malformations (ARMs) represent a complex group of congenital anomalies resulting from abnormal development of the hindgut, allantois and Mullerian duct resulting in complete or partial urorectal septal malformations. There is a wide variety of phenotypic expression, ranging from mild anorectal to very complex severe ARM with >75 % having other associated malformations. 50 % of cases are syndromic although many may have other associated anomalies. This suggests a genetic link but the genetics of ARM are highly complex with a number of candidate genes being identified. Many can be classified as "field defects" as a result of a complex set of genetic interactions. Patients with associated malformations can be classified into those with multiple congenital anomalies (non-syndromic), those with chromosomal abnormalities and those with non-chromosomal syndromic associations, also, those with non-chromosomal syndromes and the influence of environmental factors (e.g. drugs in pregnancy). Although much is not known about the aetiology of ARM, the weight of evidence points to genetic factors as major causes for the condition. In this review, we look at the chromosomal and genetic associations and their underlying signalling pathways, to obtain a better understanding of the pathogenetic mechanisms involved in developing ARM. The spectrum of ARM phenotypic expression probably results from involvement and crosstalk between a number of critical signalling systems involved in development of this region. As a result, it may be expressed as a "field developmental defect" with many associated abnormalities. The role of environmental factors in the development of ARM is probably less.

Recurrence of urorectal septum malformation sequence spectrum anomalies in siblings: time to explore the genetics

Urorectal septum malformation sequence (URSM) is a pattern of malformation which encompasses abnormalities of the perineal orifices, external genitalia, genitourinary system, and anorectum. The spectrum ranges from a complete form with absence of perineal openings and persistent cloaca to milder/partial forms usually with one perineal opening and internal abnormalities of anorectum, urethra, and Müllerian structures. URSM is felt to arise due to abnormalities of the caudal mesoderm, which constitutes the urorectal septum. Here, we report two male siblings, affected with a spectrum of anomalies simulating URSM. This is the first report of recurrence of URSM in sibs. It suggests the existence of hitherto unknown genetic mechanisms for this pattern of malformation.

Aphallia, lung agenesis and multiple defects of blastogenesis

We report the association of aphallia, with imperforate anus, bilateral renal dysplasia and complete right lung agenesis in a fetus born of non-consanguineous parents. No maternal diabetes was present. The multiple mesodermal anomalies present in this male fetus, with a severe form of Uro-Rectal-Septum Malformation Sequence associated with unilateral lung agenesis, and rib segmentation anomaly is consistent with an extended defect of blastogenesis, with apparent common timing of the malformations around the 5th to 7th weeks of gestation.

Urorectal septum malformation sequence: a report of seven cases

Urorectal septum malformation (URSM) sequence is an extremely uncommon anomaly. We report herein seven cases of URSM sequence that were identified after reviewing all autopsies conducted at our hospital over a period of 26 years (1981-2006). The URSM spectrum includes partial and full URSM sequences. Absent perineal and anal openings with ambiguous genitalia are included under 'full URSM sequence', and a single perineal or anal opening draining a common cloaca with an imperforate anus is called 'partial URSM sequence'. Of our seven cases of URSM, three were full URSM sequence and four were partial URSM sequence. Associated renal anomalies were found in all of the cases. Three cases had unilateral renal agenesis and one each had bilateral renal agenesis and bilateral renal dysplasia, respectively. The remaining two cases had unilateral renal agenesis with contralateral kidney showing features of cystic dysplastic kidney and renal hypoplasia, respectively. Congenital anomalies involving other organs were also found in some of the cases. The longest survival period in our series was 10 days, in accordance with the short survival period usually associated with URSM. Five of the patients were females, one was male, and the sex of one neonate could not be ascertained. One of the neonates was from a twin pregnancy; the other twin was normal.

Urorectal septum malformation sequence: prenatal progression, clinical report, and embryology review

The urorectal septum malformation sequence (URSMS) is characterized by severe abnormalities of the urorectal septum (URS) and urogenital organs. The primary defect in this condition appears to be a deficiency in caudal mesoderm leading to the malformation of the URS and other structures in the pelvic region. Recent clinical reports discuss prental findings of URSMS [Lubusky et al. (2006); Prenatal Diagnosis 26: 345-349]. However, here we present a case of URSMS with prenatal findings not previously described, review the literature on URSMS, and summarize current embryological understanding of the pathology seen in hindgut development. The unique prenatal finding in the patient was an abdominally located cystic mass that was first seen at 18 weeks of gestation. Over the next 6 weeks, the mass decreased in size until it disappeared. Concurrent with reduction of the cyst, ascites developed. The patient displayed several traditional URSMS indicators including abnormal bladder and dysplastic kidneys. Our findings give additional insight into the embryology of urorectogenital development. Specifically, they suggest that the cystic mass may have been a persistent urachus prior to septation of the cloaca. Postnatal evaluation confirmed a URSMS diagnosis; the newborn had ambiguous genitalia, hypoplastic kidneys, absent uterus, imperforate anus, smooth perineum, and overall underdeveloped urogenital structures.

A complex intersex condition in a Holstein calf

A case of disrupted embryonic development of the genital tract in a newborn Holstein calf is described. The physical examination of the calf evidenced several abnormalities, like atresia ani, rudimentary external genitalia and caudal vertebral agenesis. On necropsy, the excised genitalia consisted of bilateral streak gonads, apparently normal uterine tubes, a fluid-filled uterus, a long vagina and a very narrow clitoris-like structure covered with a discrete skin-fold. The urinary tract seemed normal and the urethra's opening was at the vestibule-vaginal junction. A cytogenetic analysis was requested. Karyotype revealed the existence of Y chromosome material in the two X chromosomes. However, the search for the sex-determining region Y (SRY) showed that this was an apparently absent gene. The histological examination of the gonads revealed the existence of ovarian dysplasia. Uterine sections evidenced the absence of the uterine epithelium, with only sporadic caruncles. Under microscopic examination, the uterine tubes and vagina structure was normal. The external genitalia sections revealed the existence of a skin-fold covering an erectile structure surrounding the urethra, a structure more similar to a penis than to a clitoris. This is an unusual situation of gonadal dysplasia combined with genital tract anomalies in cattle, probably associated to a genetic defect.

Congenital anomalies of the male urethra

The spectrum of congenital anomalies of the male urethra is presented. The embryologic basis of each anomaly, when known, is discussed. Clinical and imaging features of each entity are presented.

On the spectrum of limb-body wall complex, exstrophy of the cloaca, and urorectal septum malformation sequence

The limb-body wall complex (LBWC) is characterized by abdominal wall and limb defects, exstrophy of the cloaca (EC) by lack of closure of the lower abdominal wall and lack of cloacal septation, and the urorectal septum malformation sequence (URSMS) by absent perineal and anal openings, ambiguous genitalia, colonic, and renal anomalies. We report here on three fetuses whom have overlapping features of these disorders. Also we have reviewed the literature for cases with overlapping features of two or three of the above conditions. From the description of the cases reported on here and those in the literature, we propose that the overlap of features found among LBWC, EC, and URSMS represent a continuous spectrum of abnormalities, rather than three separate conditions. As such, we suggest that all three conditions may share a common etiology or pathogenetic mechanism.

Cellular proliferation in the urorectal septation complex of the human embryo at Carnegie stages 13-18: a nuclear area-based morphometric analysis

In order to analyse the patterns of cellular proliferation both in the mesenchyme of the urorectal septum (URS) and in the adjacent territories (posterior urogenital mesenchyme, anterior intestinal mesenchyme and cloacal folds mesenchyme), as well as their contribution to the process of cloacal division, a computer-assisted method was used to obtain the nuclear area of 3874 mesenchymal cells from camera lucida drawings of nuclear contours of selected sections of human embryos [Carnegie stages (CSs) 13-18]. Based on changes in the size of the nucleus during the cellular cycle, we considered proliferating cells in each territory to be those with a nuclear area over the 75th percentile. The URS showed increasing cell proliferation, with proliferation patterns that coincided closely with cloacal folds mesenchyme, and with less overall proliferation than urogenital and intestinal mesenchymes. Furthermore, at CS 18, we observed the beginning of the rupture in the cloacal membrane; however, no fusion has been demonstrated either between the URS and the cloacal membrane or between the cloacal folds. The results suggest that cloacal division depends on a morphogenetic complex where the URS adjacent territories could determine septal displacement at the time that their mesenchymes could be partially incorporated within the proliferating URS.

Urorectal septum malformation sequence

The urorectal septum malformation sequence consists of absent perineal and anal openings in association with ambiguous genitalia and urogenital, colonic, and lumbosacral anomalies. The full sequence is highly lethal, and the partial sequence, characterized by a single perineal opening draining a common cloaca, is compatible with life. Defects in mesodermal proliferation early in embryogenesis result in this rare condition. Timely urologic and surgical evaluations and reconstructions are imperative and necessary for survival. Urologists should be familiar with the mechanisms and presentations of this condition, as they may be involved in the diagnosis and management of such patients.

Megalourethra: A report of three cases associated with maternal diabetes and a review of the literature-is sonic hedgehog the common pathway?

The mechanisms by which maternal diabetes causes malformations in the offspring have yet to be elucidated. The purpose of this report is twofold: first, to describe three male infants born with multiple congenital anomalies and megalourethra, a defect which has not been previously reported in infants of women with diabetes; and second, to indicate that the defects seen in association with megalourethra in these three infants are similar to those seen as a consequence of abnormalities in sonic hedgehog, suggesting that maternal diabetes may affect sonic hedgehog expression in susceptible tissues during critical stages of development.