Limb body-wall complex in association with sirenomelia sequence

Common pathogenesis for sirenomelia, OEIS complex, limb-body wall defect, and other malformations of caudal structures

Decades of clinical, pathological, and epidemiological study and the recent application of advanced microarray and gene sequencing technologies have led to an understanding of the causes and pathogenesis of most recognized patterns of malformation. Still, there remain a number of patterns of malformation whose pathogenesis has not been established. Six such patterns of malformation are sirenomelia, VACTERL association, OEIS complex, limb-body wall defect (LBWD), urorectal septum malformation (URSM) sequence, and MURCS association, all of which predominantly affect caudal structures. On the basis of the overlap of the component malformations, the co-occurrence in individual fetuses, and the findings on fetal examination, a common pathogenesis is proposed for these patterns of malformation. The presence of a single artery in the umbilical cord provides a visible clue to the pathogenesis of all cases of sirenomelia and 30%-50% of cases of VACTERL association, OEIS complex, URSM sequence, and LBWD. The single artery is formed by a coalescence of arteries that supply the yolk sac, arises from the descending aorta high in the abdominal cavity, and redirects blood flow from the developing caudal structures of the embryo to the placenta. This phenomenon during embryogenesis is termed vitelline vascular steal.

Anatomy-based diagnostic criteria for complex body wall anomalies (CBWA)

BACKGROUND

Precise diagnosis and classification of CBWA cases can be challenging. BSA are considered when there is a body wall anomaly, skeletal abnormalities, and the umbilical cord is anomalous, absent or rudimentary, and LBWC when there is a body wall and structural limb anomalies with or without craniofacial abnormalities.

METHODS

PubMed was searched for body stalk anomalies, limb body wall complex, body stalk anomalies and amniotic band syndrome, and limb body wall complex and amniotic band syndrome. Sixty nine articles were selected and reviewed. This article systematically classifies the variants of CBWA in 218 cases, the study is based on the embryological and anatomical criteria established by Martín-Alguacil and Avedillo to study BSA in the pig.

RESULTS

Eight different BSA presentation were defined. One hundred and eighty nine cases were classified as BSA, from which five were Type I, nine Type II, 20 Type III, 57 Type IV, 11Type V, 24 Type VI, 11 Type VII, and 52 Type VIII. Twenty six cases presented cranial phenotype, 114 abdominal phenotype, 42 cranio/abdominal overlapping phenotype, and five without defined phenotype. In addition, 52 BSA cases presented some kind of spinal dysraphism (SPDYS) and were classified as BSA/SPDYS, most of these cases did not show structural limb anomalies, except for three cases and were classified as LBWC/SPDYS.

CONCLUSION

This morphology-based classification represents a useful tool for clinical diagnosis, it helps to quantify and to evaluate CBWA in a precise, objective manner.

Mermaid Syndrome: A Case Report in Mauritius

Sirenomelia is a rare congenital malformation that results in the fusion of the lower limbs together with multiple visceral anomalies. We report a case of sirenomelia observed in Mauritius and the different findings seen in the baby. The baby had fused lower extremities and bony structures for each leg were present. The umbilical cord consisted of a single artery and one vein. The external genitalia was absent and an imperforate anus was also seen. An x-ray revealed poorly expanded lungs and two distinct sets of femur and tibia were seen on imaging. However, a fused fibula and a fused talus were also noted. Multiple theories have been suggested for the pathogenesis of this condition, and despite recent progress in pathology, this condition remains debated.

Amniotic Band Syndrome With Pseudoarthrosis of Tibia and Fibula: A Case Report

Constriction of the lower limb by a congenital amniotic band has been proposed to explain the development of pseudoarthrosis of the tibia and fibula. We report a case of amniotic band syndrome in a preterm female infant with pseudoarthrosis of the tibia and fibula. She was born at 29 weeks of gestation with congenital amniotic bands and was noted to have a severely edematous left foot distal to the constricting band with rudimentary digits. The skin was pink and well perfused with palpable pulses. Radiography demonstrated pseudoarthrosis of the tibia and fibula. The limb deformities were managed with splints, positioning, and physiotherapy. She underwent Z-plasty with soft tissue release on the left lower leg on day 7 of life. At 36 weeks of postmenstrual age, a repeat radiograph showed markedly improved growth of the tibia and fibula with mature new bone formation, which avoided the need for further surgical intervention. During the follow-up period, she underwent left Syme's amputation at 18 months. At 29 months of age, the child was able to walk and run without support. The findings from our case confirm the potential for bone growth in patients with amniotic band syndrome, once the constricting band has been released. Simple release of the constriction band with Z-plasty resulted in growth of mature bone, replacing the pseudoarthrosis and, hence, the patient did not require surgical amputation. Thus, one should be cautious when deciding on surgical amputation, even in the presence of pseudoarthrosis, especially in preterm infants. Early limb-preserving surgery with release of the constricting band with an intention to salvage the limb appears appropriate.

Prenatal MRI evaluation of limb-body wall complex

BACKGROUND

The sonographic (US) features of limb-body wall complex have been well documented; however the literature regarding the findings on MRI in limb-body wall complex is scant.

OBJECTIVE

To characterize the prenatal MRI features of limb-body wall complex.

MATERIALS AND METHODS

We performed a retrospective review of all MRI scans of fetuses diagnosed with limb-body wall complex at our institution from 2001 to 2011. Fetuses without correlating US scans or follow-up information were excluded. Three pediatric radiologists blinded to the specific US findings reviewed the prenatal MRIs. Images were evaluated for the organ location and attachment, the body part affected, characterization of the body wall defect, and spinal, limb and umbilical cord abnormalities.

RESULTS

Ten subjects met inclusion criteria. MRI was able to detect and characterize the body part affected and associated abnormalities. All fetuses had ventral wall defects, a small thorax and herniated liver and bowel. The kidneys were extracorporeal in three cases. The extruded organs were attached to the placenta or the uterine wall in all cases. Abnormal spinal curvatures of various degrees of severity were present in all cases. Eight cases had a short, uncoiled cord. Limb anomalies were present in 6 of the 10 cases.

CONCLUSION

We illustrate the common fetal MRI findings of limb-body wall complex. The prenatal diagnosis of limb-body wall complex and the differentiation of this defect from treatable abdominal wall defects are crucial to providing appropriate guidance for patient counseling and management.

The epithelial mesenchymal transition process may contribute to the pathogenesis of amniotic band syndrome

The etiology of the amniotic band syndrome is unknown, and has been subject of debate since the time of Hippocrates. The most accepted theories fail to cover all the abnomalities found in affected children. During organogenesis the epithelial-mesenchymal transition process (EMTP) participates in adequate formation of different organs from three embryo layers. Altered activation of EMTP occurs when the epithelial homeostasis is disturbed, the resulting myofibroblasts are able to secrete extracellular matrix proteins and deposit them on the tissues contributing to a fibrotic phenotype. If injury occurs during organogenesis, wound healing could be exaggerated and fibrotic response could be triggered. The molecule that regulates both of these processes (EMTP and fibrosis) is the transforming growth factor β (TGFβ); indeed null animals for TGFβ isoforms show similar defects than those seen in the amniotic band syndrome. Based on documented evidence this review intends to explain how the epithelial mesenchymal transition process may contribute to the pathogenesis of amniotic band syndrome.

Sirenomelia in a Cameroonian woman: a case report and review of the literature

Sirenomelia is a rare congenital malformative disorder characterized by fusion of the lower limbs giving a characteristic mermaid-like appearance to the affected foetus. We report a case of sirenomelia occurring in a 19 year old Cameroonian woman following premature rupture of membranes and associated cord prolapse. This is the first documented case in this country. We highlight some of the cultural myths associated with this disorder and discuss our findings relative to the present literature and related controversies on its etiopathogenesis.

Comparative study of clinical characteristics of amniotic rupture sequence with and without body wall defect: further evidence for separation

BACKGROUND

Amniotic rupture sequence (ARS) is a disruption sequence presenting with fibrous bands, possibly emerging as a result of amniotic tear in the first trimester of gestation. Our comparative study aims to assess whether there is a difference in the clinical pattern of congenital limb and internal organ anomalies between ARS with body wall defect (ARS-BWD) and ARS without BWD (ARS-L).

METHODS

Among 1,706,639 births recorded between 1998 and 2006, 50 infants with a diagnosis of ARS were reported to the Polish Registry of Congenital Malformations. The information on 3 infants was incomplete, thus only 47 cases were analyzed. These infants were classified into groups of ARS-L (38 infants) and ARS-BWD (9 infants).

RESULTS

The ARS-BWD cases were more frequently affected by various congenital defects (overall p < 0.0001), and in particular by urogenital malformations (p = 0.003). In both groups, limb reduction defects occurred in approximately 80% of cases; however, minor and distal limb defects (phalangeal or digital amputation, pseudosyndactyly, constriction rings) predominated in the ARS-L group (p = 0.0008). The ARS-L group also had a higher frequency of hand and upper limb involvement.

CONCLUSIONS

This observation suggests that amniotic band adhesion in ARS-L takes place at a later development stage. Although limited by a small sample size, our study contributes to the growing evidence that both ARS entities represent two nosologically distinct conditions.

Prenatal ultrasonographical features of limb body wall complex: a review of etiopathogenesis and a new classification

Limb body wall complex is a spectrum of multiple severe anomalies. The etiopathogenesis and clinical classification are still under discussion. In our article, while reviewing previous etiopathogenetical hypothesis, we propose a new clinical classification regarding embryological theories and pheneotypical features. According to the Van Allen diagnostic criteria, the findings of 6 affected fetuses are presented. Prenatal diagnosis was performed in 5 of 6 cases. Craniofacial malformations were present in only 1 case. Thoracic defect and abdominoschisis (either infraumbilical or supraumbilical) associated with visceral eventration, placental-umbilical cord anomalies, and limb defects were detected in the other 5 cases. Aberrant development of each of the 4 embryonic folds (cephalic, 2 lateral abdominal, and caudal) associated with faulty umbilical ring development and placental formation were considered responsible for development of various malformations. In previous clinical classifications, existence or absence of the craniofacial malformation was utilized as an unique discriminating criterion while multiple anomalies exist. In this report, we propose a new clinical classification concerning almost all anomalies caused by defective placental attachment and maldevelopment of the 4 folds.

Limb-body wall complex: 4 new cases illustrating the importance of examining placenta and umbilical cord

Limb-body wall complex (LBWC) is a rare, sporadic, congenital defect defined as a combination of at least two of three characteristics: 1. limb defects, 2. anterior body wall defects, and 3. exencephaly or encephalocoele with/without facial clefts. Three pathogenic mechanisms have been proposed: early amnion rupture, vascular disruption and embryonic dysgenesis. In this study we carried out the pathological evaluation of four fetuses with LBWC and their placentas. None of the cases had craniofacial defects. Three fetuses showed an abdominal wall defect with eventration of abdominal organs, cloacal exstrophy, absent external genitalia, abnormal internal genitalia, scoliosis and lower limb defects. One fetus showed failure of closure of both thoracic and abdominal walls with ectopia cordis, evisceration of left lung and abdominal organs, severe reduction defect of left arm, but normal colon, anus, bladder, genitalia and lower limbs. All cases had a short, malformed umbilical cord, incompletely covered by amnion. The umbilical vessels were embedded in an amniotic sheet which connected the skin margin of the anterior body wall defect to the placenta. These anomalies suggest an abnormal body stalk development as a pathogenic mechanism for LBWC. Prenatally, the abnormal fetoplacental attachment can be detected ultrasonographically by the end of the first gestational trimester. Postnatally, the examination of placenta, umbilical cord and membranes is crucial in confirming the diagnosis of LBWC.

Caudal dysgenesis in staged human embryos: Carnegie stages 16-23

The severity of expression of malformations of the median axis in the caudal region of human embryos is highly variable and ranges from caudal dysgenesis and sirenomelia to simple sacral hypoplasia. Several forms of sacral dysgenesis may be discovered later in life. This shows that caudal malformations of relatively lesser severity should occur at a greater frequency than actually reported. In the present study we looked at the morphology and histology of some human embryos with caudal dysgenesis. Several developmental alterations of the median axis were observed. These included significant reduction in the craniofacial mesenchyme characterized by hypoplasia of the pharyngeal arches, palatal shelves, and agenesis or hypoplasia of the auricular hillocks at the rostral end, absence of the caudal trunk from midsacral to all coccygeal segments, vertebral fusion or agenesis, defective development of the primary and secondary neural tubes, rectal and urinary tract dysgenesis, and deficiency, malrotation, and deficiency of the limbs at the caudal end. Hindlimb malformations included bilateral agenesis (one case), meromelia, and various forms of abnormal rotation, but no instances of sirenomelia were present. Radial dysgenesis has been reported to be associated with caudal dyplasia in the literature, however, we observed agenesis of the ulna in one and of the fibula in another embryo. There was an impressive association between limb malformations and body wall defects. The histological studies demonstrated caudal vascular deficiency and hemorrhagic lesions in the limbs of the dysplastic embryos. The data suggest that these polytopic field defects arise very early in development possibly as result of disturbances to fundamental developmental events that share common molecular and cellular mechanisms.

Clinical and epidemiological characteristics of infants with body wall complex with and without limb deficiency

The spectrum of defects in cases with limb body wall complex (LBWC) is quite variable since other anomalies are also observed in infants with LBWC, and some cases do not have limb deficiencies. Van Allen et al. [Am J Med Genet 1987;28:529-548] proposed that the diagnosis of LBWC (presence of body wall defects with evisceration of thoracic and/or abdominal organs, limb deficiency, and myelocystocele) should be based on the presence of two of three of the following anomalies: exencephaly or encephalocele with facial clefts, thoraco and/or abdominoschisis, and limb defects. This approach implies that an infant with encephalocele with facial clefts and limb defects may be considered as having LBWC, which I do not think is correct. I present the results of a clinical and epidemiological analysis aimed at identifying if, from an epidemiological perspective, it is possible to identify an entity which is characterized by the presence of abdominal wall defects along with other malformations including or not limb deficiencies. The result of this analysis allows us to consider that this entity should be characterized by the presence of abdominal wall defects with a variable spectrum of anomalies (with or without limb deficiencies) and, consequently, be called body wall complex (BWC). BWC includes cases regardless of their clinical pattern and the possible etiology or pathogenetic mechanism. Thus, the BWC entity does not include amniotic band sequence without body wall defects, but does include amniotic band sequence with body wall defects.

Pathogenesis of caudal dysgenesis/sirenomelia induced by ochratoxin A in chick embryos

Caudal dysgenesis/sirenomelia is a malformation complex for which the pathogenesis is controversial. This report describes the particular vulnerability of specific caudal structures to Ochratoxin A (OA), a fungal toxin, as the basis for caudal dysgenesis in an avian model. The experimental procedure involved injection of 1 microgram of OA into the air sac of eggs that had been incubated for 48 hours prior to treatment (i.e., embryos that had reached Hamburger and Hamilton stage 9-10 (6-10 somite pairs) [Hamburger and Hamilton (1951) Dev. Dyn. 195:231-272] by the time of treatment). Six to twelve hours following OA injection, excessive cell death, as shown by vital staining and routine histology, was evident in selected cell populations, including cells of the caudal-most mesoderm (the mesoderm that apparently forms the external genitalia and median infraumbilical region), the tail bud, and the neural tube caudal to the wing buds (corresponding to the level of the presomitic mesoderm). The notochord was not severely affected, although there were degenerative changes in the presomitic mesoderm. Except for positional abnormalities, development of the lateral plate mesoderm from which the leg buds are derived appeared relatively normal in most of the treated embryos. Six days post-treatment, varying degrees of caudal dysgenesis, presenting in severely affected specimens as sirenomelia, were observed in approximately 30% of the surviving treated embryos. The potential basis for the differential vulnerability of the affected cell populations and, therefore, the cellular basis for the genesis of caudal dysgenesis/sirenomelia in this model are discussed.

Omphalocele and gastroschisis in Europe: a survey of 3 million births 1980-1990. EUROCAT Working Group

A total of 732 cases of omphalocele and 274 cases of gastroschisis was registered in 21 regional registers in Europe (EUROCAT registers) during the period 1980-1990. The total prevalence rates were 2.52 per 10,000 for omphalocele and 0.94 per 10,000 for gastroschisis. There was significant heterogeneity in total prevalence rates among regions for omphalocele. Consistently higher than average total prevalence rates of omphalocele were found in the five centers of the British Isles. This was in large part linked to the association between omphalocele and neural tube defects. A significant female excess among the cases of omphalocele associated with neural tube defects, in comparison with an insignificant male excess for other cases of omphalocele, was observed. Geographical differences in the total prevalence of gastroschisis are partly explained by differences in maternal age distributions in the populations surveyed. Omphalocele was an isolated malformation in 46% of cases; gastroschisis was isolated in 79% of cases. The average birthweight and gestational age of both isolated and multiply malformed cases of both omphalocele and gastroschisis were low, especially for multiply malformed cases, and to a greater extent for isolated gastroschisis than for isolated omphalocele. Prenatal diagnosis leading to termination of pregnancy was reported in 33.2% of omphalocele and in 26.5% of gastroschisis cases, demonstrating the considerable impact of current prenatal screening programs. On the basis of clinical manifestations, epidemiologic characteristics, and the presence and type of additional malformations, omphalocele and gastroschisis can be considered heterogeneous conditions.

A fetus with sirenomelia, omphalocele, and meningomyelocele, but normal kidneys

Sirenomelia, which has been reported for more than 450 years, is the most severe form of caudal dysplasia. This disorder is classically associated with agenesis or severe dysplasia of the urinary tract. A 27-year-old gravida 3 para 0020 presented at 19 weeks' gestation with monoamniotic twins, one normal and one with sirenomelia. The pregnancy miscarried following invasive diagnostic testing. Autopsy confirmed the findings of sirenomelia, meningomyelocele, omphalocele, persistent cloaca, and two normal kidneys. The abnormalities accompanying sirenomelia appear as a spectrum. The pathogenic theories of sirenomelia are reviewed in light of this case with normal kidneys.

Polysplenia syndrome and congenital short pancreas

We present a report of a stillborn female of mixed ancestry with congenitally short pancreas, polysplenia, congenital heart defect, normal bronchial branch pattern, and interruption of the inferior vena cava to add to the growing numbers (15) of this malformation complex in the literature. Additional manifestations were congenital hydrocephalus and absence of intestinal malrotation. A recent poster presentation at the Second International Workshop on Fetal Genetic Pathology in Montana by Drut et al. underlined the importance of reporting these cases and of the pathological examination required ["Abnormal Spleen Lobulation and Short Pancreas," in Blastogenesis-Normal and Abnormal. New York: Wiley-Liss, Inc. for the National Foundation-March of Dimes, 1993].

Omphalocele and gastroschisis: a collaborative study of five Italian congenital malformation registries

During 1984-1989, 116 cases of omphalocele and 42 cases of gastroschisis were detected among 736,760 consecutive births in the area covered by five Italian congenital malformation registries. The prevalence rate was 1.6 per 10,000 for omphalocele and 0.6 per 10,000 for gastroschisis. Three additional cases were detected among spontaneous abortions, giving a total of 117 cases of omphalocele and 44 of gastroschisis. No variations in prevalence rates were observed among registries. A cluster of omphalocele was found in 1989 in Firenze. All cases were sporadic except for one infant with two sibs with Beckwith-Wiedemann syndrome. A predominance of male infants was observed for both defects. This study confirms the very young maternal age for isolated gastroschisis as compared to that for omphalocele and controls. Birth weight and the percentage of small-for-date is different among isolated gastroschisis, omphalocele and controls. Associated anomalies occurred in 45 cases of omphalocele and 11 cases of gastroschisis. Our data confirm the association of omphalocele with trisomies 13 and 18. Twelve cases of omphalocele and gastroschisis with associated limb defects were classified as limb body wall complex. The possible differences in etiopathology between omphalocele and gastroschisis, both isolated and associated, are discussed.

Absence of limbs and gross body wall defects: an epidemiological study of related rare malformation conditions

The study is based on almost 10 million births and reports on 215 infants with two unusual malformations: amelia and gross body wall defect. Amelia without body wall defect was present in 116 cases, 67 had body wall defects without amelia, and 32 had both. The total rate was 2.2 per 100,000 births. The infants were divided into five mutually exclusive groups. There were 40 infants (0.4 per 100,000) with agenesis of the body stalk, 18 with amelia and other types of gross body wall defects (0.2 per 100,000), 56 with amelia and malformations other than gross body wall defects (0.6 per 100,000), 41 with amelia (with or without other limb reduction defects) but no nonlimb malformations (0.4 per 100,000), and 60 infants with gross body wall defects of a type other than agenesis of body stalk and without amelia (0.6 per 100,000). A weak trend of decreasing prevalence of these malformations was found during the observation period. Infants with agenesis of the body stalk and infants with amelia combined with other types of gross body wall defects occurred at an increased rate in infants of young women. This maternal age effect is also found with gastroschisis, but not with omphalocele, and may indicate etiological or pathogenetic similarities between gastroschisis and the two former groups of defect. In infants with amelia, additional limb reduction defects could be of any type: transverse, longitudinal, or intercalary. Therefore, amelia may be the end result of different types of disturbances of limb morphogenesis. There was an increased rate of twinning. The relationship with amniotic band syndrome is discussed.

Amniotic band sequence: Streeter's hypothesis reexamined

Recently published reports of 54 subjects with the amniotic band syndrome (ABS) were reviewed, paying particular attention to internal anomalies. Evidence from the internal anomalies suggests that in most cases reviewed, damage occurred in a definable time period, probably prior to 26 days postconception and before the establishment of effective embryonic circulation. Most defects are explicable in terms of interference with neuropore closure, malmigration of cephalic neural crest tissue, and damage to the mesonephros consistent with local interference of the graded expression of organizational genes resulting in a local defect in the organization of the embryo.