Umbilical Appendix Masquerading as a Patent Omphalomesenteric Duct in a Neonate.

The umbilicus is the site of a number of well-recognized and unusual abnormalities. Well-known neonatal umbilical abnormalities include umbilical hernias, granulomas/polyps, and congenital remnants of development. In this article, we describe a rare case of an appendix draining through the umbilicus of a neonate. In the literature, there are only 15 cases with possible umbilical appendix. We describe this rare case along with a review of the literature and discuss the underlying pathophysiology.

Omphalomesenteric Duct Anomalies in Children: A Multimodality Overview.

The omphalomesenteric duct is an embryologic structure that connects the yolk sac with the primitive midgut of the developing fetus. Omphalomesenteric duct anomalies include a group of entities that result from failed resorption of the omphalomesenteric duct. These anomalies include Meckel diverticulum, omphalomesenteric fistula, fibrous bands, cysts, and umbilical polyps. Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract and is usually asymptomatic. Symptoms develop when Meckel diverticulum involves complications such as hemorrhage, inflammation, and perforation, or when it causes intussusception or bowel obstruction. Hemorrhage is the most common complication of Meckel diverticulum, and technetium 99m-pertechnetate scintigraphy is the imaging modality of choice for detecting acute bleeding. US and CT are commonly used for the evaluation of patients with other complications such as obstruction and inflammation. Nevertheless, the diagnosis of these complications can be challenging, as their clinical manifestations are usually nonspecific and can masquerade as other acute intraabdominal entities such as appendicitis, inflammatory bowel disease, or other causes of bowel obstruction. There are other umbilical disorders, such as urachal remnants and umbilical granuloma, that may present with symptoms and imaging findings similar to those of omphalomesenteric duct anomalies. An accurate preoperative diagnosis of omphalomesenteric duct anomaly is crucial for appropriate management and a better outcome, particularly when these anomalies manifest as a life-threatening condition. The authors review the anatomy, clinical features, and complications of omphalomesenteric duct anomalies in children, describing the relevant differential diagnoses and associated imaging findings seen with different imaging modalities. ©RSNA, 2021.

Cutaneous presentations of omphalomesenteric duct remnant: A systematic review of the literature.

BACKGROUND: Disorders of the umbilicus are commonly seen in infancy, including hernias, infections, anomalies, granulomas, and malignancies. Meticulous inspection of the umbilicus at birth might reveal a persisting embryonic remnant, such as an omphalomesenteric duct (OMD), manifested by a variety of cutaneous signs, such as an umbilical mass, granulation tissue, or discharge. OBJECTIVE: To systematically review the available data regarding the presence and management of OMD remnant with cutaneous involvement to suggest a practical approach for diagnosis and treatment. METHODS: A systematic review of the literature evaluating OMD anomalies presenting with cutaneous symptoms was performed. In addition, an index case of an 11-month-old patient is presented. RESULTS: We included 59 publications reporting 536 cases; 97% of the patients whose age was noted were infants (mean age 11 months). In 7.5% of the cases, diagnosis was established only after treatment failure. In 6.4% of patients, nonlethal complications were reported, and in 10.3%, the outcome was death, partly due to delayed diagnosis or mismanagement. LIMITATIONS: Limited quality of the collected data, reporting bias. CONCLUSION: OMD is relatively rare; however, the clinician must consider this remnant while examining patients with umbilical abnormalities because mismanagement could cause severe morbidity and mortality.

Changes in the Prevalence of Embryologic Remnants in Umbilical Cord With Gestational Age.

The aim of this study was to examine the prevalence of embryologic remnants in umbilical cords of different gestational ages. Sections from 392 umbilical cords were examined using light microscopy. Of these, 52% contained at least 1 remnant, most commonly of the allantoic duct type. Although there was a significant decrease in vitelline duct remnants over increasing gestational age, from 11% at weeks 11-25 to 1.6% at weeks 36-42 (P = .009; χ2 test), the allantoic duct remnants remained constant in prevalence irrespective of gestational age.

Prevalence, Morphology, Embryogenesis, and Diagnostic Utility of Umbilical Cord Vitelline Vascular Remnants.

The objective of this study is to better understand embryonic vitelline vascular remnants in the umbilical cord, to assess their prevalence, to categorize their morphology, and then finally to describe and assess inflammation arising from these structures. During routine placental sign out, the author noted the presence or absence of vitelline vessel remnants for 1 year; when present, he assessed their histologic patterns and noted whether there were neutrophils marginating from the remnants and into the adjacent Wharton's jelly and whether there was any other evidence of amniotic fluid infection in sections of placental disc, membranes, or cord. All cord sections with vitelline vessel remnants were immunostained for CD15 to document any infiltrates, to highlight patterns of infiltration, and to evaluate whether mild cases of umbilical phlebitis were associated with these lesions and were at risk of being missed. Vitelline vessel remnants were present in 4.2% of placentas examined. There were 5 vitelline vessel remnant histologic patterns identified providing insight into the vitelline vessel circulation. Funisitis, primarily neutrophilic, arising from vitelline vessel remnants was present in 70.3% of the 37 cords with vitelline vessel remnants. The presence of vitelline vessel remnant funisitis documents continued active circulation in these vascular structures, and vitelline vessel remnant funisitis was associated with the presence of other placental histological evidence of amniotic fluid infection in 53.8% of cases. The author also reviews normal embryology and the pathology of vitelline vessel remnants.

Patterning mechanisms of the sub-intestinal venous plexus in zebrafish.

Despite considerable interest in angiogenesis, organ-specific angiogenesis remains less well characterized. The vessels that absorb nutrients from the yolk and later provide blood supply to the developing digestive system are primarily venous in origin. In zebrafish, these are the vessels of the Sub-intestinal venous plexus (SIVP) and they represent a new candidate model to gain an insight into the mechanisms of venous angiogenesis. Unlike other vessel beds in zebrafish, the SIVP is not stereotypically patterned and lacks obvious sources of patterning information. However, by examining the area of vessel coverage, number of compartments, proliferation and migration speed we have identified common developmental steps in SIVP formation. We applied our analysis of SIVP development to obd mutants that have a mutation in the guidance receptor PlexinD1. obd mutants show dysregulation of nearly all parameters of SIVP formation. We show that the SIVP responds to a unique combination of pathways that control both arterial and venous growth in other systems. Blocking Shh, Notch and Pdgf signaling has no effect on SIVP growth. However Vegf promotes sprouting of the predominantly venous plexus and Bmp promotes outgrowth of the structure. We propose that the SIVP is a unique model to understand novel mechanisms utilized in organ-specific angiogenesis.

The fate of the vitelline and umbilical veins during the development of the human liver.

Differentiation of endodermal cells into hepatoblasts is well studied, but the remodeling of the vitelline and umbilical veins during liver development is less well understood. We compared human embryos between 3 and 10 weeks of development with pig and mouse embryos at comparable stages, and used Amira 3D reconstruction and Cinema 4D remodeling software for visualization. The vitelline and umbilical veins enter the systemic venous sinus on each side via a common entrance, the hepatocardiac channel. During expansion into the transverse septum at Carnegie Stage (CS)12 the liver bud develops as two dorsolateral lobes or 'wings' and a single ventromedial lobe, with the liver hilum at the intersection of these lobes. The dorsolateral lobes each engulf a vitelline vein during CS13 and the ventromedial lobe both umbilical veins during CS14, but both venous systems remain temporarily identifiable inside the liver. The dominance of the left-sided umbilical vein and the rightward repositioning of the sinuatrial junction cause de novo development of left-to-right shunts between the left umbilical vein in the liver hilum and the right hepatocardiac channel (venous duct) and the right vitelline vein (portal sinus), respectively. Once these shunts have formed, portal branches develop from the intrahepatic portions of the portal vein on the right side and the umbilical vein on the left side. The gall bladder is a reliable marker for this hepatic vascular midline. We found no evidence for large-scale fragmentation of embryonic veins as claimed by the 'vestigial' theory. Instead and in agreement with the 'lineage' theory, the vitelline and umbilical veins remained temporally identifiable inside the liver after being engulfed by hepatoblasts. In agreement with the 'hemodynamic' theory, the left-right shunts develop de novo.

Hernia of the umbilical cord associated with a patent omphalomesenteric duct.

Congenital hernia of the cord is a different type of ventral abdominal wall defect in which the bowel usually herniates into the base of normally inserted umbilical cord through a patent umbilical ring. It is rare congenital anomaly with incidence of 1 in 5000. Although it was described as a distinct entity since 1920s it is often misdiagnosed as a small omphalocele. We present an unusal case of term male newborn with umbilical cord hernia associated with patent omphalomesenteric duct. The diagnose was made after birth despite antenatal ultrasound scans and it is managed successfully with uneventful recovery. If this is missdiagnosed, it could cause iatrogenic atresia of the ileum by clamping the umbilical cord after birth.

Occult Adenoma in Patent Vitellointestinal Duct Presenting as an Umbilical Fistula: Cause for Concern?

INTRODUCTION: Prevalence of vitellointestinal duct anomalies varies from 2-4%. Though a completely patent vitellointestinal duct is a common symptomatic embryological defect with a prevalence of 0.0063-0.067%, other vitellointestinal abnormalities are rarely reported. Ours is the first case to describe histopathological features of an umbilical fistula harboring an occult tubular adenoma. CASE REPORT: We report a case of one-month old child, presenting with umbilical fistula for which excision and ileal anastomosis was performed. Routine histopathologic examination revealed an occult tubular adenoma in tip of the fistula. CONCLUSION: Adenoma arising in an umbilical fistula at such an early stage of infancy has never been reported before. Detection of occult adenoma warrants screening GI endoscopy, genetic testing for syndromic gastrointestinal adenomatosis and carcinomas and lifelong surveillance. Our case highlights the importance of routine histopathologic examination in detection of occult premalignant lesions as it significantly affects the patient management and prognosis.

[Comorbid Meckel's diverticulum and omphalomesenteric cyst evaluated by small bowel series under double-balloon enteroscopy: a case report].

A 59-year-old man was referred to our hospital for examination of intermittent abdominal pain. Computed tomography scan showed a cystic lesion adjoining the ileum, and small bowel series demonstrated a small bowel diverticulum. Double-balloon enteroscopy (DBE) revealed a diverticulum in the ileum and a soft and smooth elevated lesion with a small hole at the base of the diverticulum. Small bowel series under DBE demonstrated that the cystic lesion communicated with the diverticulum through the small hole. The diagnosis was Meckel's diverticulum and an omphalomesenteric cyst. This is the first reported case of a Meckel's diverticulum and omphalomesenteric cyst communicating through a small hole without a fibrous ligament. In addition, precise evaluation was possible by small bowel series and DBE.

Mouse extraembryonic arterial vessels harbor precursors capable of maturing into definitive HSCs.

During mouse development, definitive hematopoietic stem cells (dHSCs) emerge by late E10.5 to E11 in several hematopoietic sites. Of them, the aorta-gonad-mesonephros (AGM) region drew particular attention owing to its capacity to autonomously initiate and expand dHSCs in culture, indicating its key role in HSC development. The dorsal aorta contains characteristic hematopoietic clusters and is the initial site of dHSC emergence, where they mature through vascular endothelial (VE)-cadherin(+)CD45(-)CD41(low) (type 1 pre-HSCs) and VE-cadherin(+)CD45(+) (type 2 pre-HSCs) intermediates. Although dHSCs were also found in other embryonic niches (placenta, yolk sac, and extraembryonic vessels), attempts to detect their HSC initiating potential have been unsuccessful to date. Extraembryonic arterial vessels contain hematopoietic clusters, suggesting that they develop HSCs, but functional evidence for this has been lacking. Here we show that umbilical cord and vitelline arteries (VAs), but not veins, contain pre-HSCs capable of maturing into dHSCs in the presence of exogenous interleukin 3, although in fewer numbers than the AGM region, and that pre-HSC activity in VAs increases with proximity to the embryo proper. Our functional data strongly suggest that extraembryonic arteries can actively contribute to adult hematopoiesis.

Internal herniation due to an omphalomesenteric duct cyst in a 69-year-old man.

Previous abdominal surgery is the most common cause of mechanical small bowel obstruction. However, in patients with no history of abdominal surgery, the diagnosis and treatment of mechanical small bowel obstruction is difficult. A persistent omphalomesenteric duct remnant is a rare finding that typically presents in the pediatric population and is extremely rare in patients aged > 60 years. In the present report, we describe the case of an omphalomesenteric duct cyst causing small bowel obstruction in a 69-year-old man with no history of a surgical procedure.

Aneurysmal dilatation of persistent vitelline vein with thrombus in a neonate.

The paired vitelline veins selectively involute and form a part of the portal vein during embryonic development. The presence of a persistent vitelline vein segment after birth is very rare and can be confused with anomalies of the portal and umbilical veins. We present sonographic, CT and MRI findings of aneurysmal dilatation of a persistent vitelline vein with thrombus in a neonate; this case was first misdiagnosed as an umbilical vein varix by prenatal US. MRI was used to identify the persistent vitelline vein segment and the remnant umbilical vein segment.

PATENT VITELLINE DUCT WITH GANGRENOUS SMALL BOWEL PROLAPSE: CASE REPORT AND REVIEW OF LITERATURE.

Vitelline duct anomalies (VDA) are rare complications of persistent omphalomesentric duct or vitelline duct connecting the developing embryo with the yolk sac. VDA can be asymptomatic (detected incidentally) or symptomatic, most common of which is Meckel's diverticulum. A patent vitelline duct is the. most common symptomatic presentation in African children and we present here a four day old neonate with patent vitelline duct with ileal prolapse. The neonate was operated with the patent vitelline duct and gangrenous ileum resected and end to end ileal anastomosis done.