A 2-week-old girl had been born to a 28-year-old gravida 2, para 1 mother at 39 weeks of gestation following normal spontaneous vaginal delivery. The mother had had diabetes mellitus during the pregnancy, which had been well controlled with diet. The neonatal course had been uneventful. In particular, there had been no hypoglycemia.
The umbilical cord had fallen off when the infant was 10 days old. The mother was concerned that the umbilicus of the infant looked abnormal. The umbilical protrusion did not increase in size when the infant strained or cried. There was no discharge or bleeding from the umbilicus. The infant was asymptomatic and thriving.
A PubMed search was conducted in December 2018 using the Clinical Queries tool with the key terms umbilicus cutis OR cutaneous umbilicus. The search strategy included randomized controlled trials, meta-analyses, observational studies, clinical trials, reviews, case reports, and letters to the editor. Unfortunately, no information could be retrieved from this search.
Epidemiology and Etiopathogenesis
The prevalence and incidence of umbilicus cutis is not known, because epidemiological data on this condition are lacking. In our experience, umbilicus cutis is not uncommon. To produce a normal navel, the skin of the abdominal wall joins the umbilical cord at the level of the abdomen. When the cord sloughs, only a small amount of skin at the base remains, and a normal umbilical cicatrix is formed. Umbilicus cutis results from failure of physiological infolding or involution of the periumbilical skin following separation of the cord.1
Clinically, umbilicus cutis presents as a projecting cylinder of skin in the periumbilical area that extends up the sides of the umbilical cord, forming an outpouching after the umbilical cord falls off.1 The condition is asymptomatic.
Although umbilicus cutis is usually an isolated anomaly, it has been reported to be associated with Axenfeld-Rieger syndrome and Robinow syndrome.
Axenfeld-Rieger syndrome, an autosomal dominant disorder, is characterized by mesodermal dysgenesis of the cornea and iris, strands of tissue connecting the posterior cornea to the iris, posterior embryotoxon, hypodontia of the upper incisors, oligodontia, microdontia, umbilicus cutis, prominent forehead, hypertelorism, flat nasal bridge, and maxillary hypoplasia.2-4
Robinow syndrome is characterized by skeletal anomalies (short stature, hemivertebrae, scoliosis, mesomelia, brachydactyly, syndactyly), craniofacial anomalies (midfacial hypoplasia, broad and prominent forehead, hypertelorism, wide and depressed nasal bridge, anteverted nares, tented lip, long philtrum), dental anomalies (dental crowding, hypodontia, malocclusion), and genital anomalies (micropenis in males and hypoplastic clitoris and labia majora in females).5-6
Other reported anomalies include umbilicus cutis, flat umbilicus, umbilical hernia, omphalocele, imperforate anus, choanal atresia, and congenital heart disease.2,5,6 Both autosomal dominant and recessive modes of inheritance have been described.5,6
Diagnosis and Differential Diagnosis
The diagnosis is clinical based on the characteristic physical finding. No investigation is necessary.
The differential diagnosis includes umbilical hernia, paraumbilical hernia, umbilical granuloma, umbilical polyp, patent omphalomesenteric duct, and omphalocele.
Umbilicus cutis must be differentiated from an umbilical hernia. In umbilicus cutis, there is a lack of fascial defect, and there is no further protrusion when the infant cries or strains. Classically, an umbilical hernia presents as a soft, skin-covered swelling that protrudes through the fibrous ring at the umbilicus (Figure 2).7 The umbilical bulge becomes more apparent during episodes of crying, straining, or coughing, and is easily reducible.7,8 The content usually consists of a piece of small intestine and sometimes omentum, fat, or peritoneal fluid. The condition is usually recognized in the neonatal period and is usually asymptomatic. Most umbilical hernias resolve spontaneously, usually within the first year of life.
In contrast to an umbilical hernia, a paraumbilical hernia does not protrude through the umbilical area. Rather, the hernia protrudes just above (referred to as supraumbilical hernia) (Figure 3) or below (referred to as infraumbilical hernia) the umbilicus. At times, it may be lateral to the umbilicus (Figure 4). A paraumbilical hernia is at risk for strangulation and incarceration. Also, a paraumbilical hernia usually does not resolve on its own, often requiring elective herniorrhaphy.
An umbilical granuloma forms from excess granulation tissue persisting at the base of the umbilical area after separation of the umbilical cord.9 The condition represents continuing inflammation of the granulation tissue that has not yet completely epithelialized. Delayed separation of the umbilical cord increases the risk of granuloma formation.7 The presence of saprophytic organisms in the umbilical area increases the chance of invasion by pathogenic organisms.
Typically, an umbilical granuloma presents as a red papule or a pedunculated mass that has a soft, moist, velvety, and friable appearance (Figure 5).7,9,10 The size ranges from 3 to 10 mm in diameter.7,10,11 Persistent serosanguinous or serous discharge from the mass is characteristic.10,12 The mass may bleed with minimal contact.10 An umbilical granuloma usually responds to cauterization with silver nitrate.
An umbilical polyp (also known as omphalomesenteric duct polyp) is a remnant of the omphalomesenteric duct (also known as vitelline duct) with enteric mucosa at the umbilicus but with no intestinal connection.13-15 Clinically, an umbilical polyp presents as a painless, reddish, firm mass at the umbilicus with mucoid/blood/serous/serosanguinous discharge (Figure 6).12,13,16 The mass has a smooth surface. Characteristically, an umbilical polyp presents in the neonatal period and does not respond to cauterization with silver nitrate.12,14
The omphalomesenteric duct usually closes between the fifth and seventh week of gestation.14 Persistence and patency of the omphalomesenteric duct results in a fistula connecting the terminal ileum to the umbilicus.17 A patent omphalomesenteric duct typically presents with an umbilical discharge that is often feculent but may also be bilious or serous (Figure 7).11,13,17,18 Less commonly, a patent omphalomesenteric duct presents with an umbilical mass.18
An omphalocele is a congenital anomaly of the anterior abdominal wall in which the abdominal viscera herniates through a central defect at the site of the umbilical ring (Figure 8).19,20 An omphalocele presents as an umbilical mass covered by a translucent membrane that is composed of peritoneum on the inner surface, amnion on the outer surface, and Wharton jelly between the layers.19 The umbilical vessels insert into the membranous sac, and the rectus abdominis muscles insert laterally on the costal margins. The defect is usually in the mid abdomen and rarely occurs in the upper or lower abdomen.
Omphaloceles vary in size, and they can contain small intestine, large intestine, stomach, liver, spleen, urinary bladder, or gonads.19,21
Complications and Management
Umbilical cutis is a benign anomaly. The condition, however, can be cosmetically unsightly and socially embarrassing for those wearing swimming suits.
While no treatment is necessary, plastic surgery for cosmetic purposes may be considered.
Authors: Alexander K. C. Leung, MD; Amy A. M. Leung, MD; and Alex H. Wong, MD