Pediatric Annals

Special Issue Article 

A Review of Benign Congenital Anomalies

Wisdeen Wu, DO, FAAP; Deepak Kamat, MD, PhD, FAAP


Benign congenital anomalies are common in neonates. Some of these common benign congenital anomalies include preauricular pits, sacral dimples, supernumerary digits, accessory nipple, and natal teeth. It is important for health care providers who take care of newborns to recognize these benign anomalies so that unnecessary evaluations and investigations are not performed. However, some of these anomalies may be associated with clinically significant conditions. In this article, we discuss when further evaluation should be performed in babies presenting with these common benign congenital anomalies. [Pediatr Ann. 2020;49(2):e66–e70.]


Benign congenital anomalies are common in neonates. Some of these common benign congenital anomalies include preauricular pits, sacral dimples, supernumerary digits, accessory nipple, and natal teeth. It is important for health care providers who take care of newborns to recognize these benign anomalies so that unnecessary evaluations and investigations are not performed. However, some of these anomalies may be associated with clinically significant conditions. In this article, we discuss when further evaluation should be performed in babies presenting with these common benign congenital anomalies. [Pediatr Ann. 2020;49(2):e66–e70.]

Congenital anomalies in the neonate are commonly identified at delivery or at the first few outpatient well-visits during infancy. It is important for the general practitioner to be familiar with these anomalies so that proper advice can be provided to the families or appropriate evaluation performed to delineate the congenital anomaly. This article outlines several common benign anomalies, their etiologies, and their appropriate management.

Preauricular Pits

A preauricular pit or sinus is a small dimple that is typically located anterior to the tragus or helix. The incidence of preauricular pits is less than 1% of the population in the United States. The preauricular sinus develops because of the incomplete fusion of the first and second branchial arch structures between gestational weeks 6 and 9.1 They can be unilateral or bilateral, with right-sided lesions being more common. They occur sporadically or have a variable autosomal dominant inheritance.2 Bilateral pits are more commonly inherited than unilateral pits.

Preauricular pits can be associated with syndromes, such as branchio-oto-renal syndrome. Pits are present in 3% to 10% of these cases.2 As the name suggests, this syndrome is associated with branchial arch anomalies, hearing loss, and renal anomalies. Branchio-oto-renal syndrome has an autosomal dominant inheritance pattern, so the physician should inquire about a family history of hearing loss or renal anomalies.1 Preauricular pits and tags are found in other craniofacial syndromes as well, and further evaluation should be pursued if multiple anomalies or dysmorphic features are present with the preauricular pits or tags. An audiologic examination should be performed to rule out hearing loss in a child when a syndrome is suspected, because incidence of hearing loss is high in these patients.

Preauricular pits can become infected and usually present with typical signs of infection and/or inflammation, such as edema, pain, erythema, and drainage. Antibiotic coverage for Staphylococcus and Streptococcus species is appropriate. Recurrent infections may warrant a referral to a head and neck surgeon for complete surgical excision.

There is some controversy regarding the association of preauricular pits and hearing loss. Some studies suggest that isolated pits without other risk factors or an otologic surgical history do not have an increased risk for hearing loss,3 whereas other studies have reported a higher risk of conductive hearing loss with isolated preauricular pits and tags even when other risk factors are not present.4 In the United States, because of the universal newborn hearing screening program, most cases of hearing loss are detected with otoacoustic emissions testing, and further audiologic testing with auditory brainstem response is pursued when hearing loss continues to be a concern.4

Another consideration with preauricular pits and tags is renal anomalies. Renal ultrasound is recommended when an additional risk factor such as dysmorphic features, family history of hearing loss or renal abnormalities, or maternal history of gestational diabetes is present.5 An isolated preauricular pit or tag does not require evaluation with a renal ultrasound, as the incidence of renal abnormalities in patients with isolated preauricular pits or tag is comparable to the general population.6

Sacral Dimples

Sacral dimples and pits are other common congenital anomalies that are identified in the newborn period. A sacral dimple or pit is found commonly overlying the sacral bone or towards the gluteal cleft. The characteristics of most sacral pits are a solitary pit with an easily visible base, less than 5 mm in size, and no more than 2.5 cm above the anal opening. They occur in 2% to 4% of normal newborns.7

Sacral dimples associated with other physical findings is an indication for imaging studies to look for occult spinal dysraphisms. Sacral dimples can be associated with underlying neural tube defects, which occur due to incomplete cell migration during the embryologic process of neural tube development and neurulation.8 The specific cutaneous lesions that are associated with occult spinal dysraphisms are subcutaneous lipoma, skin tag, deviation of the gluteal fold, hemangioma, hairy patch, depigmented macule, and vascular nevus. In addition, the occult spinal dysraphism is common if the dimple is not midline, is greater than 5 mm in size, is porous, has a “cigarette burn” appearance, or is too close or far away from the anus.9 Because these lesions have a higher incidence of underlying spinal cord abnormalities, it warrants imaging studies and may possibly require surgical intervention. An ultrasound is often the first imaging study performed for suspected occult spinal dysraphism. Magnetic resonance imaging can also be performed when a lesion has atypical cutaneous findings or if there is an abnormal neurologic examination.7 In studies in which screening ultrasounds were performed for simple sacral dimples, 80% to 96% had normal results.10,11 In one large study, only 0.13% of the healthy infants who had an abnormal screening ultrasound and abnormal results on subsequent imaging studies received surgical intervention.11

Thus, in an otherwise healthy infant, simple sacral dimples and pits do not require ultrasound or other imaging studies unless there are additional abnormal overlying skin findings or there are other systemic congenital anomalies.

Supernumerary Digits

Supernumerary digits are a common abnormality that is easily identified at delivery. These extra digits are also referred to as polydactyly, and they are classified based on the location of the extra digit and whether the digit involves only soft tissue or bone. They can occur spontaneously, although familial cases of polydactyly are well documented. Familial types are often inherited in an autosomal dominant pattern, and familial polydactyly more commonly occurs bilaterally and symmetrically.12 The etiology of polydactyly is thought to be the failure of multiple cell signaling pathways to arrest continued growth during limb development as an embryo.13 In our discussion below, we focus primarily on supernumerary digits of the hand.

The most common type of supernumerary digit is classified as post-axial polydactyly, in which the extra digit is located on the ulnar side of the hand. It is further classified into type A, where a bony structure is attached to the hand, or type B, where only a skin bridge attaches the digit to the hand.14 A post-axial type B digit is the most commonly occurring form of polydactyly in the United States. The incidence of post-axial type B polydactyly in the US varies from 1 in 100 to 300 in black children to 1 in 1,500 in white children.14 These digits are nonfunctional appendages. Palpation of bony elements can be confirmed with radiograph, because further management of any digit with bony structures will require a surgical removal.

Traditionally, post-axial type B polydactyly has been ligated in the outpatient setting or nursery with suture ligation. Some document successful removal using topical anesthetic only, with minimal complications in the nursery setting.15 Others report good results in an office-based procedure for removal using injectable lidocaine and epinephrine. These authors highlight the cost-effectiveness of outpatient management, along with the avoidance of general anesthesia at a young age.16 On the other hand, the risk of simple ligation is the development of amputation neuroma, which is a residual stump of tissue that has significant pain and sensitivity. A small case study examined children and their parents with supernumerary digits who had suture ligation performed on their supernumerary digits at a young age.17 Many parents continued with pain, irritation, and sensitivity at the sites of ligations, and histologic examination revealed neurologic tissue growth in these residual stumps. Thus, these authors consider the risk for later complication of amputation neuroma as a possible reason for proper surgical removal instead, although further studies need to be performed to confirm these findings.17

Another type of supernumerary digit is a digit located on the radial side of the hand, which is called pre-axial polydactyly. This is less common than post-axial polydactyly, with an incidence of 1 in 1,000 births, 14 and the surgical management depends on the type of duplication that occurs. Pre-axial polydactyly can be associated with other syndromes, such as Holt-Oram syndrome or Rubenstein-Taybi syndrome. In general, surgical management is recommended, with the timing depending on the lesion and the preference of the individual surgical team.14

Identifying the type and location of the supernumerary digit helps to inform parents on management plans. Although these are often benign findings at delivery, they may have cosmetic, cultural, or even functional implications for the child. It is appropriate to refer parents to a specialist such as an orthopedist, plastic surgeon, or dermatologist to help determine the best timing for surgical intervention.

Accessory Nipple

An accessory nipple, also referred to as polythelia, appears as extra darkened tissue with a flat or raised surface, typically along the milk lines on the anterior chest, although they can occur anywhere. The incidence of an accessory nipple varies in the literature. It was identified in 25 per 1,000 infants in one study, with a unilateral nipple identified more commonly than bilateral accessory nipples.18 Another study found a prevalence of 5.6% in their population, with a higher prevalence of an accessory nipple found in males than females and more commonly on the left side.19 Varying degrees of breast tissue, from a simple accessory nipple to an accessory nipple with an areola or full accessory glandular breast tissue, have been described. An isolated accessory nipple is generally thought to be asymptomatic, but pain during menstruation has been described and needs to be discussed with parents or caregivers.20

A higher incidence of renal anomalies in Italian and Hungarian children with accessory nipples has been reported.21,22 The renal anomalies reported include renal or ureteral duplication, single kidney, renal agenesis, renal hypoplasia, multicystic kidney, and horseshoe kidney. These studies recommend that renal ultrasound should be performed to screen for renal abnormalities when accessory nipple is identified in their specific population.21,22 A more recent study concludes no association between an accessory nipple and renal anomalies, based on the observation that an accessory nipple is not found more frequently in children with known renal anomalies identified on imaging studies.23 These authors highlight the small sample size and specific populations in previous studies as a possible reason for higher prevalence reported in those studies.23 Thus, currently there is no evidence to support evaluation for renal anomalies in neonates with accessory nipples. One study reports an association between supernumerary nipples with renal cell or breast carcinoma, although these are thought to be rare.20 Anticipatory guidance and monitoring for possible growth over time is appropriate for conservative management given the benign nature of an accessory nipple. If desired by the caregivers, referral to a dermatologist can help confirm the diagnoses for removal for cosmetic reason.

Natal Teeth

Natal teeth are teeth found at the time of birth, and neonatal teeth appear during the first 30 days of life. The prevalence of natal teeth ranges from 1 in 1,400 to 1 in 3,400 births.24,25 They occur most commonly as mandibular central incisors, although they may also occur as maxillary central incisors, mandibular canines, and molars. They are often found as a pair of teeth, rather than a single tooth. The etiology of natal teeth remains unclear. Some studies suggest a hereditary component to natal teeth, as they have been reported in families. Some natal teeth have been determined to be early primary teeth, and supernumerary teeth comprise less than 10% of the natal teeth.25 They may appear yellow-brown in color and have a conical shape. Many may have hypoplastic enamel, and they may not have roots or have only rudimentary roots. They may also be partially erupted through the gumline.26,27

Natal teeth can also be associated with other conditions and syndromes. They are commonly found in children with cleft lip and palate. Other syndromes that have been identified with natal teeth include cleidocranial dysplasia, familial adenomatous polyposis, Nance-Horan syndrome, trichorinophalangeal syndrome, Rubenstein-Taybi syndrome, Opitz G/BBB syndrome, and oculofaciocardiodental syndrome.28 Therefore, a genetic consult is necessary when natal teeth are identified with other significant congenital abnormalities.

Management of natal teeth depends on several factors, including hypermobility of the tooth and risk of aspiration, difficulty in feeding, and ulceration of the tongue. The mobility of a natal tooth can be a risk for aspiration as the infant is learning to feed and suckle. If the tooth is not mobile and does not interfere with breast-feeding or bottle feeding, then monitoring is recommended.29 A rare complication of natal teeth is called Riga-Fedes syndrome, in which the ventral surface of the tongue develops traumatic ulceration due to natal teeth. The ulceration may cause pain and difficulty with feeding. It can be managed with observation or with a safe barrier to the area to allow healing.30 In general, in the presence of hypermobility of the tooth, difficulty feeding, or ulceration on the tongue, a referral to a pediatric dentist will be helpful in determining the best time and method for extraction. Some authors recommend waiting for extraction until after 10 days of life, when the neonate's vitamin K production is usually established by the intestinal flora and liver. When waiting is not an option, they recommend providing a prophylactic administration of intramuscular vitamin K to reduce the risk of hemorrhage.26,29 After extraction, the infant should continue follow-up care with a pediatric dentist to monitor for appropriate dental eruption and any other complications.

In summary, when natal teeth are identified, examining the mobility of the tooth and feeding habits of the neonate will assist in counseling parents and caregivers on further management.


Benign congenital anomalies in neonates are common. Most of them do not need any intervention other than close observation. Some of them, however, are associated with other conditions or syndromes and, therefore, may need further evaluation in terms of imaging studies and/or consultation with specialists such as a geneticist, nephrologist, orthopedist, or dentist. Thus, recognizing those newborns who would need further evaluation is crucial to prevent morbidity and mortality.


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Wisdeen Wu, DO, FAAP, is an Assistant Professor, General Pediatrics, University of Texas Health San Antonio. Deepak Kamat, MD, PhD, FAAP, is a Professor of Pediatrics and the Vice Chair for Academic Affairs, Department of Pediatrics, University of Texas Health San Antonio.

Address correspondence to Wisdeen Wu, DO, FAAP, University of Texas Health San Antonio, 7703 Floyd Curl Drive, Mail Code 7808, San Antonio, TX 78229; email:

Disclosure: The authors have no relevant financial relationships to disclose.


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