Anal and ano-urogenital malformations: a histopathological study of "imperforate anus" with a reconstruction of the pathogenesis

Congenital Pouch Colon: Further Histopathological Perspectives

Congenital pouch colon is an uncommon anomaly worldwide and is usually associated with anorectal malformations. Imperforate anus with a large air fluid level on the abdominal x ray suggests the diagnosis. Most cases are diagnosed in neonates and an early management limit complications. Few studies have documented the histopathological features of congenital pouch colon. We present two cases with varied associated anomalies (Case 1 with rectovesical fistula, Case 2 with Mayer Rokitansky Kuster Hauser syndrome) and their histopathological features. Immunohistochemistry for calretinin showed paucity of ganglion cells and intrinsic fibers with occasional punctate positivity. The c-Kit immunostain documented fewer interstitial cells of Cajal. Cystitis glandularis with intestinal metaplasia (Case 1) and an additional muscle layer (Case 2) are described. These novel histopathological features characterize the entity further and may be related to genesis of the pouch and its clinical manifestations.

[Morphological criteria for surgical treatment of anorectal malformations in children]

OBJECTIVE

To improve treatment outcomes in patients with anorectal malformations via research of morphological criteria and differentiated approach to surgical correction.

MATERIAL AND METHODS

There were 37 children with various types of anorectal malformations for the period 2000-2019. We analyzed morphological features of atretic rectum wall, fistula, anastomosis with adjacent organs and skin of the perineum.

RESULTS

Morphological research of anorectal malformations made it possible to differentiate treatment strategy and explain the causes of unsatisfactory results after perineal and abdominal-perineal proctoplasty. Incidence and severity of complications, as well as early disability were reduced that significantly improved postoperative quality of life.

CONCLUSION

According to the morphological criteria, deeper mobilization of atretic rectum within at least 2.5-3 cm of the rectal «cone» with intact muscular wall is necessary. This approach was valuable to ensure adequate closure function of the rectum, prevent anal incontinence and restore normal appearance of the perineum. These achievements contributed to decrease in the incidence of admissions, redo surgeries and improvement of social adaptation in children.

The development of the cloaca in the human embryo

Subdivision of cloaca into urogenital and anorectal passages has remained controversial because of disagreements about the identity and role of the septum developing between both passages. This study aimed to clarify the development of the cloaca using a quantitative 3D morphological approach in human embryos of 4–10 post‐fertilisation weeks. Embryos were visualised with Amira 3D‐reconstruction and Cinema 4D‐remodelling software. Distances between landmarks were computed with Amira3D software. Our main finding was a pronounced difference in growth between rapidly expanding central and ventral parts, and slowly or non‐growing cranial and dorsal parts. The entrance of the Wolffian duct into the cloaca proved a stable landmark that remained linked to the position of vertebra S3. Suppressed growth in the cranial cloaca resulted in an apparent craniodorsal migration of the entrance of the Wolffian duct, while suppressed growth in the dorsal cloaca changed the entrance of the hindgut from cranial to dorsal on the cloaca. Transformation of this ‘end‐to‐end’ into an ‘end‐to‐side’ junction produced temporary ‘lateral (Rathke's) folds’. The persistent difference in dorsoventral growth straightened the embryonic caudal body axis and concomitantly extended the frontally oriented ‘urorectal (Tourneux's) septum’ caudally between the ventral urogenital and dorsal anorectal parts of the cloaca. The dorsoventral growth difference also divided the cloacal membrane into a well‐developed ventral urethral plate and a thin dorsal cloacal membrane proper, which ruptured at 6.5 weeks. The expansion of the pericloacal mesenchyme followed the dorsoventral growth difference and produced the genital tubercle. Dysregulation of dorsal cloacal development is probably an important cause of anorectal malformations: too little regressive development may result in anorectal agenesis, and too much regression in stenosis or atresia of the remaining part of the dorsal cloaca.

Anorectal Malformations: Histomorphological and Immunohistochemical Evaluation of Neuronal Dysfunction

Objective :

The patients with anorectal malformations (ARM) have been identified with specific and non-specific pathological changes. The present study was conducted with the aim to study histomorphological changes and various immunohistochemical (IHC) markers (calretinin, S-100, CD117) in intestinal wall specimens to assess neuronal dysfunction in ARM patients.

Material and methods :

Thirty children having ARM were included in our study. In all the cases, a representative biopsy was received. The tissue sections were processed and wax blocks were prepared. Various histopathological changes were examined on routine H&E. Representative sections were further subjected to IHC staining for ganglion cells (calretinin), interstitial cells of Cajal (CD117) and nerve bundles (S-100 protein). Descriptive variables were analyzed to assess neuronal dysfunction in cases of ARM. Chi-square was used to compare the categorical values. P-value <0.05 was accepted as statistically significant.

Results :

Biopsies were studied for histological changes using H&E stain. The most frequently observed histological finding in mucosa was inflammation and congestion in 87% and 67% of cases respectively. Disrupted muscularis mucosa was observed in 60%, eroded mucosa in 57%, and hemorrhage in 40% of cases. Submucosal inflammation and congestion were most common finding observed in submucosa in 87% and 80% cases respectively. CD117 was used to demonstrate altered density and distribution of interstitial cells of Cajal (ICC) in cases of ARM. Majority of them belong to grade 2+ category (n=17, 57%) followed by grade 1+ (n=8, 17%) for ICC cells. Altered density and distribution of ICC was observed in ARM which was statistically significant (p=0.02).

Conclusion :

The malformed segments in ARM show various specific and non-specific histomorphological changes. Examination of H&E sections along with IHC stains evaluation can minimize need for repeated biopsies and unnecessary radical treatment. CD117 immunohistochemistry is reliable adjunctive test in evaluation of ICC in motility disorders of bowel. Calretinin is good marker for identification of ganglion cells. In ARM, density and distribution of ICCs is significantly altered which can explain postoperative dysmotility.

Low-type anorectal malformations in the male: Extent of deviation from the norm

PURPOSE

To define the degree of deviation from the norm among boys with minor forms of anorectal malformations (ARM).

PATIENTS AND METHODS

Between March 2015 and January 2016, we studied the preoperative MRI of nine boys with low-type ARM. For comparison, we included another nine boys (control group) who underwent MRI pelvis for causes other than ARM (e.g. impalpable testes).

RESULTS

In boys with low-type ARM, the rectum descends forwards to touch the back of the prostate (as in the norm), but then goes downwards (with little or no backward deflection) keeping intimately attached to the bulb of the corpus spongiosum and displacing it downwards and forwards. The striated sphincter muscles do not follow the anterior displacement of the bowel termination, but remain orthotopically compacted at the normal predestined site of the anal canal.

CONCLUSION

Among boys with low ARM, the minor abnormalities at the external anal orifice are associated with deeper anatomical aberrations in the form of anterior misplacement of the anorectum. These findings may help in understanding the disturbed act of defecation among these patients, and provide guidance to the best way of surgical correction.

Urethral duplication in girls: Three cases associating an accessory epispadiac urethra and a main hypospadiac urethra

INTRODUCTION

Urethral duplication is extremely rare in girls, with less than 40 cases reported so far. Most of them present as a prepubic sinus. Literature is scare regarding aetiology, classification and management in other forms. This study presents three cases of sagittal urethral duplication in girls presenting a main hypospadiac urethra and an accessory epispadiac urethra.

PATIENTS AND METHODS

Medical records were retrospectively reviewed of three girls with urethral duplication managed over a 30-year period at a single institution. Circumstances of diagnosis, management and outcomes were analysed.

RESULTS

The oldest case presented as a neonatal retrovesical mass with an accessory clitoral stream, whereas the two more recent cases presented with antenatal hydrocolpos and bilateral ureterohydronephrosis. Cases 1 and 3 had an incomplete duplication, while Case 2 had a complete form. In Case 3, the duplication was associated with a urogenital sinus and an anteriorly placed anus. Management involved resection of the epispadiac accessory urethra to achieve continence, with dilatation and/or mobilisation of the hypospadiac one. All girls are now aged >5 years old and are continent, and one is old enough to have normal menstruation. Renal function is normal in all. The summary table presents the schematic anatomical description as shown on micturating cystourethrogram and endoscopy, as well as the management for each patient.

DISCUSSION

Step-by-step management is necessary in urethral duplication. The neonatal emergency is to release the urinary tract compression by evacuating urinary retention or hydrocolpos. Later in infancy, decision has to be taken regarding the urethras. If the resection of the epispadiac accessory urethra seems acceptable to achieve continence, the attitude towards the hypospadiac channel is more controversial and should be individualised. Embryologic and aetiopathogenic pathways are still missing to uniformly characterise the malformation.

CONCLUSION

Paediatric urologists should remember that there is a wide spectrum of urethral duplication in girls, and that various presentations exist beside the more classic prepubic sinus.

Fetal growth of the anal sinus and sphincters, especially in relation to anal anomalies

PURPOSE AND METHODS

The anal sinuses, small furrows above the pectinate line, sometimes form perianal abscesses in adults. We examined the pattern of fetal growth of the anal sinus and sphincters using 22 mid-term (8-18 weeks) and 6 late-stage (30-38 weeks) fetuses.

RESULTS

In mid-term fetuses, the external and internal sphincters gradually increased in thickness, depending on specimen size (from 0.2 to 1.5 mm), whereas the anteroposterior diameter of the anal canal at the epithelial junction was relatively stable (0.5-1.0 mm) irrespective of specimen size. Anal canal diameter increased less than twofold between mid-term and late-stage fetuses, from 0.5-1.0 to almost 2 mm, whereas sphincter thickness increased over tenfold, from 0.2-1.5 to almost 3.5 mm. The anal sinus often showed balloon-like enlargement when the sphincter muscle bundles were tightly packed in mid-term, but not in late-stage fetuses.

CONCLUSIONS

Large concentric mechanical stress from the sphincters in late-stage fetuses apparently prevented the anal sinus from expanding in a balloon-like manner. Conversely, to avoid anal stenosis, the growing sinuses maintained a luminal space of the anal canal in response to stress from rapidly growing sphincters. The inferiorly extending sinus usually provided temporal double canals separated by a thick column. In the presence of double lumens, anal canal duplication is likely to develop without any abnormalities of the anal epithelium and sphincters.

The anomalous clinical anatomy of congenital pouch colon in girls

BACKGROUND/PURPOSE

The aim of this study was to evaluate the anomalous clinical anatomy of congenital pouch colon (CPC) associated with anorectal agenesis in 22 consecutive girls managed over a study period of 7 years.

METHODS

The 22 patients were categorized into 2 groups. Group A consisted of 10 patients who presented during the neonatal period (n = 9) or as a young infant (n = 1). In these patients, only preliminary assessment results were available. Group B (12 patients) comprised 5 newborns who remained on follow-up and 7 patients who presented after the age of 1 year. These 12 patients were assessed and investigated in more detail.

RESULTS

In group A patients, apart from absence of the normal anal opening, the appearance of the external genitalia and perineum was essentially normal. Retraction of the labial folds showed radiation of folds inward from the margins of the vulval vestibule toward the center, at a point of confluence located at a higher level. At laparotomy, the subtypes of CPC were type I (n = 4), type II (n = 5), and type III (n = 1). In 8 patients, uterus didelphys was present. In all group B patients, the appearance of the external genitalia was similar to that in group A patients. However, separate openings of the urethra, septate vagina, and vestibular fistula (if present) were visible in 5 patients, whereas in 3 patients, a single perineal opening was identified. A total of 9/12 patients (75%) had urinary incontinence. Examination under anesthesia and endoscopy revealed a septate vagina in all 12 patients and an open, incompetent bladder neck with reduced bladder capacity in the 9 patients with urinary incontinence. The terminal fistula of the colonic pouch opened just distal to the bladder neck (n = 1), just posterior and cephalad to the urethral opening (n = 2), low in the vestibule (n = 5), and undetermined (n = 4). The subtypes of CPC were type I CPC (n = 2), type II CPC (n = 9), and type III CPC (n = 1). All 12 patients had uterus didelphys.

CONCLUSIONS

The characteristics in the anomalous clinical anatomy of CPC in girls, as described here, appear to be almost invariable and, especially in regions where CPC is common, should alert the clinician to the presence of this malformation.

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.

Development of the external anal sphincter with special reference to intergender difference: observations of mid-term fetuses (15-30 weeks of gestation)

To investigate intergender differences in muscle cleavage and joining during development of the external anal sphincter (EAS), we examined semiserial sections of 16 fetuses between 15 and 30 weeks of gestation (6 males and 10 females). The subcutaneous part of the EAS (EASsc) developed along the male perineal raphe and extended posteriorly. Thus, the male EAS was characterized by anterior protrusion of the subcutaneous muscle, in contrast to the almost circular female EAS. In both genders, the bulbospongiosus anlage (or the levator ani anlage) issued muscle fibers to form the superficial (or deep) part of the EAS. The EASsc communicated with the superficial part in males, whereas the female bulbospongiosus tended to communicate with the levator ani rather than the EAS. In both genders, the longitudinal muscle bundle(s) of the anorectum contributed to perineal body formation. However, the male perineal body also had a thick fascia between the rhabdosphincter and the levator. The bulbospongiosus seems to play a critical role in forming the EAS. A strict intergender difference in subcutaneous muscle development is evident along the perineal raphe, as the raphe is not evident in females. These results help to explain variations in the EAS, including anal malformations.

Duplication of accessory phallic urethra (urethra triplication) in the female, signaling mesenchymal interruptions of the cloacal membrane as a cause for sagittal urethral duplications

A specimen of accessory phallic urethra duplication (triplication) in a 32.5-week gestation female was studied histologically. The specimen demonstrated an anterior "phallic urethra" ending inside a penoclitoral organ in a megalourethra-like dilatation with a narrow epispadiac meatus and "anterior urethrocutaneous fistula" and a posterior canal opening with the anal canal. With histology suggestive of a split persistent urogenital sinus, correlation to normal development strongly suggests an error in the formation of the cloacal membrane and developing superficial cloaca at 26 to 29 days' ovulation age (2 to 4 mm), causing an isolated interruption of the membrane by mesenchyme, which by participating in the growth of the early cloaca may extend as far as the vaginal orifice later. Differences in number, position, and size of such mesenchymal interruptions can explain other duplications and triplications and offer a single alternative for the many current theories of pathogenesis, none of which are compatible with new insights in normal development.

Penislike clitorises with megalourethras in nonvirilized female fetuses and a newborn. A histopathologic study and its bearing on their pathogenesis

PURPOSE

The aim of the study was to analyze the microstructure of penislike clitorises in female pseudohermaphroditism in relation to their pathogenesis.

METHODS

Penislike clitorises from 2 fetuses and 1 newborn with anorectal malformations and multiple other caudal anomalies and 1 fetus with phallic urethra duplication were histologically examined in toto.

RESULTS

The penislike clitorises revealed basically female features in the histogenesis of the corpora cavernosa and glans and in the absence of penile raphe, septum, fasciae, and periurethral glands. In 2 cases, the "phallic urethra" was completely surrounded by a single corpus cavernosum and in 3 cases by a circular glans. Labia minora and vestibular bulbs had not developed in 3 cases. The urethras had transformed into fusiform or scaphoid megalourethras with stenotic meatuses in 3 specimens and an extra orifice in the fourth specimen.

CONCLUSIONS

Penislike clitorises in female pseudohermaphroditism show a fundamental dysgenesis of major structural elements. The pattern favors the hypothesis of an early error in the formation of the cloacal membrane and adjacent cloaca in embryos between 26 and 29 days postovulation that may lead to dysregulation of molecular developmental interactions during the following formation of the genital tubercle.

Common ("classical") and covered cloacal exstrophy: a histopathological study and a reconstruction of the pathogenesis

Current opinion about structure and pathogenesis of cloacal exstrophy was challenged by histopathological findings and new insights into the normal development. Autopsy specimens of common (n = 3) and covered cloacal exstrophy (n = 4) with single intraexstrophic and -perineal phallic structures and perineo-exstrophic canals have been analyzed histopathologically. The findings were correlated to normal development to reconstruct the pathogenesis. By identifying a specific cloaca-derived urethra field as distinct from allantois-derived bladder fields, the exstrophic area is found to reflect the original hindgut configuration in embryos of approximately 26-29 postovulatory days gestational age (2-4 mm). Correlation to normal development suggests malfunctioning of the primitive streak/caudal eminence as a primary fault that leads to a defective cloacal region in the hindgut disturbing cloacal-intestinal-allantoic dissociation and also causes lengthening of the intestinal region into a blind-ending colon, teratoma-like lesions, and vertebral and muscular anomalies. The current idea that membranes in "covered cloacal exstrophy" represent persisting cloacal membranes is dismissed by finding an amnion-like structure, which suggests dysfunction of an umbilical ring placode as a simultaneous 2nd fault. This malfunctioning may cause omphalocele by defective demarcation of the umbilical cord and may replace midline stroma of the infraumbilical abdominal wall by extraembryonic tissue that stretches into a weak temporary membrane, may leave a perineo-extrophic canal, and may allow the formation of a single perineal or intraexstrophic phallus. Malfunctioning without replacement may result in a purely epithelial "allantoic" membrane, which by disintegrating in combination with the cloacal membrane will expose common cloacal exstrophy.

The colovesical fistula in congenital pouch colon: a histologic study

PURPOSE

The aim of this study was to perform a detailed histopathologic examination of the terminal colonic pouch and the colovesical fistula (CVF) excised during surgical management of male patients with the more severe forms (types I/II) of congenital pouch colon (CPC) associated with anorectal agenesis.

METHODS

From January 2005 to December 2006, 25 male patients with types I/II CPC underwent abdominal exploration with dissection of the terminal portion of the colonic pouch and associated CVF till the bladder, division-ligation of the fistula, and excision of the colonic pouch. In 6 of the 25 patients, a complete dissection of the fistula to the bladder was possible, and in them, the terminal portion of the colonic pouch and the CVF were subjected to detailed histopathologic examination. The 6 patients included 3 newborns in whom this surgery was performed as a primary procedure, and 3 patients aged 3 months, 15 months, and 2 years, respectively, in whom a window colostomy of the pouch had earlier been performed. After due processing, multiple sections from the specimens were stained using the routine H&E method and examined under the microscope under different magnifications.

RESULTS

In 4 specimens, the epithelial lining of the CVF consisted of transitional stratified epithelium with underlying anal/urethral glands. In 2 specimens, obtained from patients 15 months and 2 years old, respectively, the lining was of nonkeratinizing, stratified squamous epithelium. Other findings included aganglionosis in the muscle layers (n = 2), submucosal and subserosal fibrosis (n = 1), and thickening of muscle layers in the fistulous portion, suggestive of the presence of an internal sphincter (n = 2).

CONCLUSIONS

The CVF in patients with types I/II CPC shows histologic features of the normal anorectal canal.

Primary presacral neuroendocrine tumor associated with imperforate anus

Background

Presacral masses are unusual growths that have a limited differential diagnosis, typically not including neuroendocrine tumors (NETs). Classically, NETs are well-differentiated gastroenteropancreatic tumors of probable benign behavior. These tumors are associated with a typical morphologic pattern and involve the distal colon, rectum, and genitourinary tract; they are considered less aggressive, frequently asymptomatic, and rarely cause carcinoid syndrome, even when metastatic. Neuroendocrine tumors of the presacral region are extremely rare and few have been described in the literature. They have not been previously reported as being associated with imperforate anus.

Case presentation

We present an interesting case of a woman with a history of imperforate anus that was found to have a primary neuroendocrine tumor of the presacral region with no rectal wall involvement.

Conclusion

We argue that this is a primary gastroenteropancreatic neuroendocrine tumor which likely originated from cells of hindgut origin that underwent an abnormal migration during embryonic development.

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.