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

A fetus of partial urorectal septum malformation sequence characterized by complete septate uterus: A case report

RATIONALE

Urorectal septum malformation sequence (URSMS) is an extremely uncommon anomaly characterized by imperforate anus accompanied by multiple genitourinary malformations. Here, we report a case of URSMS identified by the autopsy and classified into partial URSMS. Prenatal diagnosis is challenging for clinicians due to the difficulty of early identification of URSMS and the relative lack of specific features in ultrasound. We intend to share our experiences.

PATIENT CONCERNS

One fetus was indicated abdominal cystic structure, abdominal effusion and right renal pelvis separation (7 mm) by ultrasound at 28 + 1 week's gestation. After the pregnancy was terminated, the fetal tissues were performed to be tested by autopsy, copy number variation sequencing and whole exon sequencing.

DIAGNOSES

Based on the clinical characteristics, ultrasound, autopsy, and genetic test findings, the fetus was diagnosed with URSMS.

INTERVENTIONS

After genetic counseling, the couple opted to terminate her pregnancy.

OUTCOMES

The copy number variation results of the fetus showed a 0.48-MB duplication fragment of uncertain significance on chromosome 8p23.3, while the whole-exome sequencing revealed a SAL-LIKE 1 gene mutation. The autopsy of the fetus showed imperforate anusa, the abdominal cyst was further confirmed with complete septate uterus and the lower urethra and vagina converge formed a lumen.

LESSONS

Individuals with URSMS during the fetal period might be misdiagnosed due to atypical features of URSMS. Once structural abnormalities especially cystic mass of the futuses in the lower abdomen, URSMS should be considered.

Won't You be My Neighbor: How Epithelial Cells Connect Together to Build Global Tissue Polarity

Epithelial tissues form continuous barriers to protect against external environments. Within these tissues, epithelial cells build environment-facing apical membranes, junction complexes that anchor neighbors together, and basolateral surfaces that face other cells. Critically, to form a continuous apical barrier, neighboring epithelial cells must align their apico-basolateral axes to create global polarity along the entire tissue. Here, we will review mechanisms of global tissue-level polarity establishment, with a focus on how neighboring epithelial cells of different origins align their apical surfaces. Epithelial cells with different developmental origins and/or that polarize at different times and places must align their respective apico-basolateral axes. Connecting different epithelial tissues into continuous sheets or tubes, termed epithelial fusion, has been most extensively studied in cases where neighboring cells initially dock at an apical-to-apical interface. However, epithelial cells can also meet basal-to-basal, posing several challenges for apical continuity. Pre-existing basement membrane between the tissues must be remodeled and/or removed, the cells involved in docking are specialized, and new cell-cell adhesions are formed. Each of these challenges can involve changes to apico-basolateral polarity of epithelial cells. This minireview highlights several in vivo examples of basal docking and how apico-basolateral polarity changes during epithelial fusion. Understanding the specific molecular mechanisms of basal docking is an area ripe for further exploration that will shed light on complex morphogenetic events that sculpt developing organisms and on the cellular mechanisms that can go awry during diseases involving the formation of cysts, fistulas, atresias, and metastases.

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.

An Autopsy Case Report: Prune Belly Syndrome with Overlapping Presentation of Partial Urorectal Septum Malformation Sequence

Prune belly syndrome (PBS) is characterized by a classical triad of congenitally absent abdominal muscles, bilateral cryptorchidism, and a malformed urinary tract. Urorectal septum malformation sequence (URSM) is identified with the absence of urogenital and anal openings. This case report describes a 15-week-old female fetus with megacystis, ascites and oligohydramnios in a 19-year-old nulliparous woman. The patient underwent preterm labor at the 33rd gestational week and delivered a female newborn weighing 2250 grams who died three days later due to progressive respiratory insufficiency. To the best of our knowledge, this is the third case of an overlap between PBS and URSM in literature. Such an overlap refers to the existence of left renal agenesis, right renal cystic dysplasia, bilateral club foot and lumbar scoliosis as well as the absence of abdominal wall muscles, internal genital organs, urethral, vaginal and anal openings. This case report aims to remind the obstetricians about the concurrent occurrence of PBS with URSM and its poor prognosis.

Genetic Analysis of KRT9 Gene Revealed Previously Known Mutations and Genotype-Phenotype Correlations in Epidermolytic Palmoplantar Keratoderma

Epidermolytic palmoplantar keratoderma (EPPK, OMIM 144200) is an autosomal dominant inherited disease, clinically characterized by diffuse yellowish thickening of the skin on the palms and soles, usually with erythematous borders developing during the first weeks or months after birth. Pathogenesis of EPPK is determined by mutations in the keratin gene (KRT9). Thirty three mutations in the KRT9 gene from 100 EPPK families have been identified. Among these, 23 mutations are located in the 1A region (a mutation hot spot region), 7 are located in the 2B region, and the remaining 3 are synonymous mutations. In this study, three heterozygous mutations (p.N161S, p.R163W, and p.R163Q), located in regions of the gene encoding the conserved central a-helix rod domain, were detected in the KRT9 gene of the three large Chinese families. This study confirms that codon 163 (48 of 100 cases) is a hot spot mutation site for KRT9. Additional findings identified p.N161S (4%) and p.R163W (4%) as potential hot spot mutations for EPPK associated with knuckle pads, and p.R163Q (15 of 100 cases) as the hot spot mutation of EPPK not occurring in combination with knuckle pads. In conjunction with future studies, this research may help lay the foundation for genetics counseling, prenatal diagnosis and clinical treatment of EPPK.

Variant Presentations of the Exstrophy-Epispadias Complex: A 40-Year Experience

OBJECTIVE

To investigate the diagnosis, surgical management, and outcomes in patients with variant EEC. Variant presentations of the exstrophy-epispadias complex (EEC) span a wide range of abnormalities. The rarity and diversity of EEC variants can lead to challenges in the diagnosis and subsequent management of this population.

METHODS

The authors reviewed an institutional database of 1336 EEC patients from 1975 to 2018 for variant presentations of EEC. Variant presentations included those with skin covered bladder exstrophy (BE), duplicate bladders, superior vesical fistula, and epispadias with major bladder prolapse. Surgical management and outcomes were assessed.

RESULTS

In total, 44 EEC variants were identified. Nineteen (43%) presented with a skin-covered BE variant. Five patients presented with duplicate BE, while 6 presented with superior vesical fistula. Fourteen patients (32%) presented with epispadias with major bladder prolapse. Overall, 36 (82%) EEC variants underwent primary bladder closure, at a median of 135 days after birth (range 1-2010), with 21 (58%) undergoing pelvic osteotomy. Primary closures were successful in 89% of cases. Continence procedures were performed in 17 patients. This includes 5 patients who underwent bladder augmentation. However even without a continence procedure, continence with volitional voiding was found in 8 patients.

CONCLUSION

The most common EEC variant is the skin-covered form of BE. In order to expedite appropriate management, accurate diagnosis upon initial presentation is crucial. Still, successful surgical reconstruction often results in continence that is similar to, or better than, nonvariant EEC presentations.

Prenatal sonographic diagnosis of urorectal septum malformation sequence and chromosomal microarray analysis: A case report and review of the literature

INTRODUCTION

Urorectal septum malformation sequence (URSMS) is a rare congenital abnormal syndrome that is caused by the incomplete division of the cloaca. Based on whether the cloaca membrane breaks down or not, the URSMS are classified as full and partial forms. The prenatal diagnosis of URSMS remains challenging because of poor recognition to this malformation and the relatively non-specific sonographic features. We report a prenatally sonographic diagnosed case of the partial URSMS, and review the literature to summarize the prenatal features.

CASE REPORT AND REVIEW

A 37-year old woman was referred at 24 weeks of gestation for fetal abdominal cyst. Detailed sonographic examination was done and revealed the vesicocolic fistula, distended colon, absence of perianal hypoechoic ring, pyelectasis, and small stomach bubble. The URSMS was suspected.Amniocentesis was done and karyotyping revealed 46,XY. Furthermore, chromosomal microarray analysis (CMA) was performed for the first time in URSMS and an alteration of 111.8Kb deletion was detected in 16p13.3 which was located inside the RBFOX1 gene. Parental studies showed that the deletion was inherited from the father who has nomal clinical phenotype.The woman elected to terminate the pregnancy at 25 weeks gestation and postmortem examination confirmed the diagnosis of partial URSMS.The published studies were reviewed and 28 cases of URSMS with conducted prenatal ultrasonography were collected in this report. The most common sonographic description, as suspicious signs of URSMS, were severe oligohydramnios or anhydramnios, urinary tract anomalies, fetal intra-abdominal cysts, and dilated bowel. Also, enterolithiasis and vesicocolic fistula were relatively infrequent but highly specific feature of URSMS.

CONCLUSIONS

URSMS is difficult to be diagnosed prenatally. However, it has characteristic features that can be detected by fetal ultrasonography, and a precise prenatal sonographic examination is crucial for diagnosing URSMS. Besides, more genomic profiling studies are needed to elucidate the causality.

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.

Development of the external genitalia and their sexual dimorphic regulation in mice

The study of the external genitalia is divided into 2 developmental stages: the formation and growth of a bipotential genital tubercle (GT) and the sexual differentiation of the male and female GT. The sexually dimorphic processes, which occur during the second part of GT differentiation, are suggested to be governed by androgen signaling and more recently crosstalk with other signaling factors. The process of elucidating the regulatory mechanisms of hormone signaling towards other signaling networks in the GT is still in its early stages. Nevertheless, it is becoming a productive area of research. This review summarizes various studies on the development of the murine GT and the defining characteristics of a masculinized GT and presents the different signaling pathways possibly involved during masculinization.

Ascites, hydrocolpos, hydrometrocolpos with normal amniotic fluid in a fetus with partial urorectal septum malformation sequence

Urorectal septum malformation sequence (URSMS) describes a range of anatomic anomalies in the urogenital and lower gastrointestinal organs caused by incomplete urorectal membrane septation and persistence of the cloacal membrane. Partial URSMS is a milder version characterized by a single perineal opening. We report a case of partial URSMS that associated an intact Mullerian system, single perineal opening, blind colon, imperforate anus and vagina, urethrovaginal connection, and ambiguous genitalia. Hydrocolpos, hydrometrocolpos, and ascites were seen in utero and confirmed on postnatal surgery. This case describes the changes in sonographic findings that evolved throughout the gestation.

Ulcerative colitis of the neovagina as a postsurgical complication of persistent cloaca

Persistent cloaca is characterized by a common vestibule connected to the bladder, uterus, and rectum and a single perineal orifice to the exterior. Treatment can involve vaginal reconstruction with sigmoid/descending colon. We report a case of an 8-year-old girl who, as an infant, underwent vaginoplasty using sigmoid colon for persistent cloaca and developed a fulminant colitis that also affected the colonic neovagina 2 years after her reconstruction.

Normal development of hindgut and anorectum in human embryo

PURPOSE

The aim of the present analysis is to examine the morphological changes, the spatiotemporal distribution of apoptosis/proliferation in the human embryonic anorectum, to reveal the normal development of human anorectum, and investigate the possible roles of apoptosis/proliferation during anorectal development.

MATERIALS AND METHODS

The embryos were sectioned serially and sagittally, stained with hematoxylin and eosin (H & E) between the third and eighth week of gestation, TdT-mediated dUTP-digoxigenin nick end-labeling (TUNEL) and proliferative cell-specific nuclear antigen (PCNA) immunohistochemical staining from the sixth to the eighth week.

RESULTS

From the fourth to the seventh week, with the growth of the mesenchyme around the cloaca, the cloaca was remolded, subsequently, the cloacal membrane (CM) moved perpendicularly then horizontally. The dorsal cloaca gradually descended to the tail groove, the urorectal septum (URS) and the CM approximated; however, the fusion of URS with the dorsal CM was never observed. During the eighth week, the URS shifted ventrally and finally fused with the ventral CM. Moreover, from the sixth to the eighth week, the apoptotic cells were concentrated in the CM, the mesenchyme of terminal rectum, and the dorsal rectum. Meanwhile, the proliferative cells could be observed in the ventral mesenchyme around the cloaca, the CM, the fused tissue between the URS, and the ventral CM.

CONCLUSIONS

During the development of human anorectum, it was intriguing to reveal that the URS never fused with the dorsal CM before dorsal CM disintegration, the normal anorectal development may depend on the dorsal cloaca and the dorsal CM; furthermore, the distribution of apoptosis and proliferation in the anorectum and ventral cloacal mesenchyme played a pivotal role in the formation of the anorectum.

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.