Cutaneous developmental anomalies in the newborn and infant

INTRODUCTION — Developmental anomalies that involve the skin present in most cases at birth or in the first few months or years of life [1,2]. Common locations include the head, nose, preauricular area, neck, and spine.

Congenital cutaneous anomalies vary in severity, from minor findings of cosmetic significance only to severe deformities. Some may be cutaneous markers of underlying malformations or components of complex syndromes.

This topic will review common and uncommon cutaneous developmental anomalies that are seen in the newborn and infant. Other skin lesions in newborns and infants are reviewed separately.

●(See "Skin lesions in the newborn and infant".)

●(See "Vesicular, pustular, and bullous lesions in the newborn and infant".)

●(See "Skin nodules in newborns and infants".)

●(See "Congenital melanocytic nevi".)

EPIDEMIOLOGY — The incidence of cutaneous developmental anomalies in newborns is unknown. In prospective, cross-sectional studies of skin findings in neonates, minor anomalies like accessory tragus, "skin tags," adnexal polyps, and preauricular pits were found at a rate of 0.1 to 2.5 percent each [3-6]. In an outpatient neonatal dermatology clinic, the overall prevalence of congenital skin anomalies was 4.8 percent [7].

HEAD AND NECK

Preauricular pits and sinuses — Preauricular pits are common, small depressions at the anterior margin of the ascending limb of the helix (picture 1). They are in most cases an isolated finding but in 3 to 10 percent of cases may be associated with extracutaneous anomalies [8]. Preauricular cysts are swellings in the preauricular area that may drain fluid or pus if there is a sinus tract. Surgical excision is the treatment of choice for cysts and sinuses but not pits. (See "Congenital anomalies of the ear", section on 'Outer ear malformations'.)

Accessory tragus — Accessory tragus is a common congenital anomaly of the external ear [9]. It presents as a small, dome-shaped, skin-colored papule or nodule that may be soft or firm, usually located in the preauricular area or along a line drawn from the tragus to the corner of the mouth (picture 2). They may contain a cartilaginous core and may be single or multiple, and bilateral. They are generally isolated findings, though they can be associated with some rare disorders, including Goldenhar and Treacher Collins syndromes, among others. Excision is usually performed for cosmetic purpose. (See "Congenital anomalies of the ear", section on 'Outer ear malformations' and "Syndromes with craniofacial abnormalities", section on 'Treacher Collins syndrome'.)

Congenital cartilaginous rests of the neck — Congenital cartilaginous rests of the neck, also called cervical tabs or cervical wattles, are rare congenital anomalies thought to be remnants of branchial arches. They present as skin-colored, soft nodules typically located on the lower third of the neck, the anterior border of the sternocleidomastoid muscle (picture 3) [10]. Histologically, there is ectopic cartilaginous tissue covered with normal epidermis. Surgical excision is usually performed for cosmetic reasons.

Branchial cysts, clefts, and sinuses — Branchial cysts, clefts, and sinuses are congenital anomalies that represent, in the majority of cases, remnants of the second branchial cleft (figure 1) [11]. They are usually present at birth, although they may not become apparent for several years. Branchial cysts are painless, mobile swellings that occur on the lateral aspect of the upper neck along the sternocleidomastoid muscle (picture 4). They may swell with respiratory tract infections. Branchial sinuses and clefts are noted at birth or within the first few years of life along the lateral lower third of the neck. All branchial lesions should be addressed surgically. (See "Differential diagnosis of a neck mass", section on 'Branchial cleft cyst'.)

Thyroglossal duct cysts — Thyroglossal duct cysts (thyroglossal duct remnants) are the most common cause of congenital neck masses [12,13]. They present as soft, painless masses located on the midline anywhere from the base of the tongue to the suprasternal notch along the migration site of the rudimentary thyroid gland; a sinus tract may be present (picture 5A-B) [14]. Ultrasound examination is an appropriate imaging technique for initial evaluation [15,16]. Treatment is surgical excision; recurrence is reported in approximately 10 percent of cases [17]. (See "Differential diagnosis of a neck mass", section on 'Thyroglossal duct cyst'.)

Bronchogenic cysts and sinuses — Bronchogenic cysts are uncommon developmental anomalies derived from the embryonal foregut or trachea. These lesions are usually apparent at birth and found in the chest or mediastinum. More rarely, they may be found in the skin, typically in the suprasternal notch, presternal area, or lateral or medial neck [18,19]. Several cases presenting in the scapular area have also been reported [20-22]. They are usually asymptomatic swellings that may discharge fluid and are typically not associated with any other abnormalities. Treatment is surgical excision. (See "Congenital anomalies of the intrathoracic airways and tracheoesophageal fistula", section on 'Bronchogenic cyst'.)

Midline anterior neck inclusion cyst — Midline anterior neck inclusion cysts (MANICs) are superficial anterior neck cysts that are present at birth and resemble giant milia [23-25]. They are thought to be a forme fruste of a developmental fusion defect occurring at a very superficial level. Reported cases do not have deep extension and are lined with stratified squamous epithelium akin to a follicular inclusion cyst [23]. They can be distinguished from other anterior neck developmental anomalies by their small size; superficial location in the skin; and characteristic appearance as white, round, exophytic or dome-shaped papules resembling giant milia. They can be removed with shave or snip excision or curettage and may also spontaneously regress.

Cranial dysraphism — Closed or small neural tube defects may present with cutaneous scalp lesions (neuroglial heterotopia of the scalp), which may include firm or cystic swellings, all located along or close to the midline scalp in frontal, parietal, and occipital regions [26]. These nodular lesions are in most cases accompanied by an overlying alopecic area surrounded by localized hypertrichosis, the "hair-collar" sign (picture 6), and by a capillary stain [27]. The lesions usually contain ectopic leptomeningeal or glial tissue confined to the dermis and subcutis but may contain ectopic brain tissue or may communicate intracranially. Thus, all midline cranial lesions in newborns must be evaluated with magnetic resonance imaging (MRI) before intervention is undertaken.

Open neural tube defects are discussed separately. (See "Primary (congenital) encephalocele".)

Nasal gliomas — Nasal gliomas (also called nasal glial heterotopia or neuroglial heterotopia) are congenital midline masses due to ectopic rests of neuroglial tissue that do not have patent intracranial connection [26]. They may be external, intranasal, or both. They present as firm, nontender, skin-colored or red-bluish nodules at the root of the nose. They are frequently misdiagnosed as hemangiomas but do not respond to standard therapies for infantile hemangiomas. Surgical excision is the preferred treatment. (See "Congenital anomalies of the nose", section on 'Nasal gliomas'.)

Cranial dermoid cysts and dermal sinus tracts — Dermoid cysts are congenital lesions that present as subcutaneous nodules seen along embryonic fusion lines on the face, scalp, and spine and contain epidermal and dermal tissues [26]. The most common locations include the anterior fontanelle, the junction of the sagittal and coronal sutures on the scalp, the upper lateral region of the forehead near the eyebrow (picture 7), and in the submental region. They do not transilluminate, and overlying skin is usually normal (though there may be a pit or sinus). They usually are adherent to underlying periosteum. (See "Skin nodules in newborns and infants", section on 'Cysts'.)

Dermal sinuses are small tracts that connect a dermoid cyst to the surface of the skin. They are found on the midline nose, occipital scalp, and spine, often with a small tuft of hair protruding from the surface [28]. These lesions may communicate with the central nervous system, putting the patient at risk for meningitis. All midline lesions should be evaluated radiologically before surgical intervention.

Aplasia cutis — Membranous aplasia cutis presents at birth as a well-marginated, round or oval lesion resembling a cyst or bulla on the scalp midline (picture 8). It is thought to be a "forme fruste" variant of neural tube defect. Aplasia cutis is discussed in greater detail separately. (See "Aplasia cutis congenita".)

TRUNK

Congenital sternoclavicular sinus — Congenital sternoclavicular sinus, also called congenital dermoid sinus or congenital dermoid fistula of the anterior chest region, is a rare congenital anomaly presenting as a pit located at the sternoclavicular joint, most often on the left side [29-31]. A white/yellow, solid drainage when squeezing has been reported in many cases. Secondary infection and abscess formation are common. The embryologic origin of sternoclavicular sinus is uncertain. It has been suggested that it may be related to the fourth branchial remnant fistula [31]. Treatment is surgical.

Supernumerary nipples — Supernumerary (or accessory) nipples, also called polythelia, are the most common variant of accessory mammary tissue [32]. They are found along the embryologic milk lines from the axillae to inner thighs. Lesions are typically subtle in newborns but may appear as light brown papules a few millimeters in size (picture 9A-B). Excision is not necessary unless glandular tissue is present, as this may enlarge at puberty. (See "Breast disorders in children and adolescents", section on 'Congenital abnormalities'.)

Congenital anetoderma — Congenital anetoderma is a rare congenital anomaly seen in very premature infants [33,34]. It presents with round areas of cutaneous atrophy on the trunk or proximal limbs. It should be distinguished from the iatrogenic anetoderma of prematurity, which becomes apparent weeks to months after birth in preterm infants, typically at sites where monitoring leads or gel electrocardiographic electrodes were previously placed (picture 10). (See "Anetoderma", section on 'Iatrogenic anetoderma of prematurity'.)

Supraumbilical cleft — Supraumbilical clefts are midline defects that occur as a result of disruption of abdominal wall fusion. They are rarely an isolated finding. In most cases, midline clefts are associated with hemangiomas and other cardiovascular anomalies in PHACE (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac anomalies, and eye anomalies) syndrome [35]. (See "PHACE syndrome", section on 'Ventral midline anomalies'.)

Cutaneous signs of spinal dysraphism — Closed spinal dysraphism may present with several cutaneous signs in the midline, including hypertrichosis; lipomas; capillary malformations and hemangiomas (picture 11); sacral dimples (picture 12), especially if located at more than 2.5 cm from the anal verge; aplasia cutis; acrochordons (picture 13); dermoid cyst or dermal sinus tracts (picture 14) [36]; and faun tail nevus [26]. Magnetic resonance imaging (MRI) is the imaging modality of choice, followed by surgical intervention if needed. (See "Closed spinal dysraphism: Clinical manifestations, diagnosis, and management", section on 'Clinical manifestations'.)

Cutaneous dimples — Skin dimples are common and most frequently seen overlying joints [37]. The vast majority are benign, but some may be associated with various rare disorders and fetal mechanical trauma [38].

Adnexal polyp of neonatal skin — Adnexal polyps are small, skin-colored pedunculated papules on the chest, usually on or medial to the areola (picture 15) [39,40]. They are congenital and usually fall off after birth, though they may persist.

Anomalies of the umbilicus

Umbilical granuloma — Umbilical granulomas are pink to red, friable, velvety papules on the umbilical stump that bleed easily (picture 16A-C) [41]. They must be differentiated from other umbilical anomalies, such as patent urachus and omphalomesenteric duct remnant. Umbilical granulomas usually resolve with application of silver nitrate. (See "Care of the umbilicus and management of umbilical disorders", section on 'Umbilical granuloma'.)

Patent urachus — Patent urachus is a rare urachal anomaly that may result in drainage of urine from the umbilical stump. (See "Care of the umbilicus and management of umbilical disorders", section on 'Urachal anomalies'.)

Omphalomesenteric duct remnant — Omphalomesenteric duct remnants present in most cases as bright red umbilical polyps or masses or as a nonspecific, discharging lesion of the umbilical stump (picture 17) [42-44]. Umbilical polyps are often misdiagnosed as umbilical granuloma, but they typically do not respond to cauterization with silver nitrate. Surgical excision is the treatment of choice [45]. (See "Care of the umbilicus and management of umbilical disorders", section on 'Umbilical polyp'.)

EXTREMITIES

Supernumerary digits (polydactyly) — Polydactyly is one of the most common congenital limb anomalies [46]. It can occur as an isolated finding or in association with other congenital anomalies (syndromic polydactyly) [47]. Supernumerary digits of the hand are most often found on the lateral (ulnar) surface of the fifth digit (postaxial polydactyly). They may be small, pedunculated papules or fully formed digits. Treatment is surgical. (See "Assessment of the newborn infant", section on 'Extremities'.)

Amniotic bands — Fibrous bands may form in the amniotic sac and cause disruption of the growing fetus (amniotic band syndrome) [48]. The most common skin finding is a constriction band of the distal extremity, which is usually circumferential and may result in distal amputations (picture 18A-B) [49]. (See "Amniotic band sequence".)

SUMMARY

●Head and neck region – Lesions that can be seen in the head and neck region include ear anomalies, such as preauricular pits (picture 1) and sinuses and accessory tragi (picture 2); branchial cysts and sinuses (picture 4); thyroglossal duct cysts (picture 5A-B); bronchogenic cysts and sinuses; cranial dysraphism (picture 6); and dermoid cysts and dermal sinus tracts (picture 7). (See 'Head and neck' above.)

●Trunk – Supernumerary nipples are the most common variant of accessory mammary tissue. They are found along the embryologic milk lines from the axillae to inner thighs (picture 9A-B).

Umbilical anomalies include umbilical granulomas (picture 16B) and umbilical polyps (picture 17). (See 'Trunk' above and 'Supernumerary nipples' above and 'Anomalies of the umbilicus' above.)

●Midline truncal lesions – Of particular importance are midline truncal lesions that may be associated with closed spinal dysraphism, including capillary malformations and hemangiomas (picture 11), sacral dimples (picture 12), acrochordons (picture 13), dermoid cysts or sinuses, and faun tail nevus. (See "Closed spinal dysraphism: Clinical manifestations, diagnosis, and management", section on 'Clinical manifestations'.)

●Extremities – Polydactyly (supernumerary digits) is one of the most common congenital limb anomalies, most frequently found on the lateral surface of the fifth hand digit. Amniotic bands causing limb constriction may result in distal amputations (picture 18A-B). (See 'Extremities' above.)