INTRODUCTION — Defects in the formation and growth of the midface lead to a variety of malformations. The embryology, clinical features, and management of congenital anomalies of the nose are reviewed here. Other congenital anomalies (including those of the ear and upper respiratory tract) and the approach to congenital malformations more broadly are discussed separately:
EMBRYOLOGY — The nose arises from the nasal placodes during the third and fourth weeks of intrauterine life. Each nasal placode is a local thickening of the surface ectoderm on the lateral surface of the head of the embryo, just above the oral stoma. The nasal placodes sink into the mesenchyme to form the depressions that will become the nostrils. Hypertrophy of the tissue surrounding the nasal placodes creates the medial and lateral nasal prominences (picture 1).
The nostrils migrate medially, and their soft tissues fuse as the orbits begin their medial migration. The medial nasal processes form the anterior nasal septum, mid-upper lip, and a portion of the anterior hard palate. The nasofrontal process originates from the floor of the anterior cranial fossa as a division of the prosencephalon. The nasofrontal process forms the posterior nasal septum and the ethmoid, nasal, and premaxillary bones. The posterior nasal and oral cavities are separated by the oronasal membrane until the sixth or seventh week of intrauterine life, when the oronasal membrane is resorbed to form the primitive choanae.
The prenasal space is located between the nasal and frontal bones during embryogenesis. It extends from the nasal skin to the foramen cecum, an area of the anterior cranial fossa where some prolapse of the dura may occur. The foramen cecum fuses with the fonticulus frontalis to form the cribriform plate .
ARHINIA — Arhinia, or absence of the nose, is a rare anomaly that may cause neonatal respiratory distress at birth due to upper airway obstruction (picture 2) . Arhinia is presumed to result from a specific defect in the nasal placodes or surrounding neural crest-derived tissues during embryonic development. It is variably associated with absent paranasal sinuses, hypertelorism, microphthalmia, colobomas, nasolacrimal duct abnormalities, midface hypoplasia, high-arched palate, absent olfactory bulbs, and defects of the reproductive axis in males . In a study that performed DNA sequencing of 40 people with arhinia, 84 percent had a missense mutation in the SMCHD1 gene . While surgical reconstruction is possible, nasal prostheses may produce superior results .
SUPERNUMERARY NOSTRIL — Supernumerary nostril is a rare malformation of the nose, characterized by an accessory, eccentric nasal opening, either connecting to the ipsilateral nasal cavity or terminating in a blind pouch (picture 3). Its cause is not known, but the defect likely occurs between the fifth and seventh weeks of embryogenesis . It should be differentiated from the double nose, or polyrrhinia, where there may be two septae and four nostrils and nasal cavities . Surgical treatment usually consists of excision of the fistulous tract with plastic closure. Narrowing of the nasal base may be required, as with cleft nose deformities .
HOLOPROSENCEPHALY — Holoprosencephaly is the most common developmental defect of the forebrain, characterized by inadequate or absent midline division of the forebrain into cerebral hemispheres, with concomitant midline facial defects in the majority of cases.
The clinical manifestations of holoprosencephaly range from an isolated single maxillary incisor to cebocephaly (eg, small mouth, single nostril, and close-set eyes) or cyclopia (picture 4 and image 1). The brain may be normal, but incomplete separation of the hemispheres (semilobar holoprosencephaly), single common ventricle (picture 5), and absence of the corpus callosum (alobar holoprosencephaly) are frequent occurrences. As a general rule, the more severe the facial malformations, the worse the abnormalities of the central nervous system. The more severe forms of holoprosencephaly often are lethal. Intellectual disability and seizures are common occurrences in survivors. Children with semilobar holoprosencephaly may be asymptomatic and have normal mentation.
Solitary median maxillary incisor syndrome likely represents a holoprosencephaly variant .
Holoprosencephaly is discussed in greater detail separately. (See "Overview of craniofacial clefts and holoprosencephaly", section on 'Holoprosencephaly'.)
FRONTONASAL DYSPLASIA — In contrast with holoprosencephaly, frontonasal dysplasia (median cleft face syndrome) is characterized by hypertelorism, widow's peak (ie, V-shaped frontal hairline), cranium bifidum occultum ("cleft skull"), and a median cleft of the upper lip and palate (figure 1) . The classification system for craniofacial clefts numbers clefts based upon their location surrounding the orbit arranged in a counterclockwise direction (figure 2). Frontonasal dysplasia is classified as number 14 cleft.
The frontonasal dysplasia sequence is thought to be caused by a primary defect in the nasofrontal process that prevents appropriate migration to the midline. It is associated with loss-of-function mutations in the ALX homeobox gene family . Craniofacial surgery may be required to improve appearance .
Craniofacial clefts, including frontonasal dysplasia, are discussed separately. (See "Overview of craniofacial clefts and holoprosencephaly", section on 'Craniofacial clefts'.)
NASAL DERMOIDS — Nasal dermoid sinuses and cysts result from congenital fusion abnormalities at the nasal root. Nasal dermoids are epithelium-lined sinus tracts that extend from the root or tip of the nose through the nasal septum to the anterior cranial fossa.
●Pathogenesis – Nasal dermoid sinuses and cysts account for 1 percent of all dermoid cysts and between 3 and 12 percent of dermoids of the head and neck . Familial occurrence and autosomal dominant inheritance have been described [13,14].
Two theories attempt to explain the origin of nasal dermoids :
•Cranial origin theory – Nasal dermoids result from the faulty recession of the dura mater from the prenasal space during normal embryogenesis
•Superficial inclusion theory – Nasal dermoids are formed by the submucosal trapping of ectoderm during the fusion of the lateral nasal processes
●Clinical features – Nasal dermoids are classically described as noncompressible masses over the nasal dorsum with an associated midline pit or punctum anywhere along the dorsal surface of the nose (picture 6) [16-21]. The lesions have been variably described as pale, flesh-colored, pearly, or erythematous [22,23]. An unusual but important presentation is that of an ill-defined, yellowish plaque of the midline nasal dorsum . The ability to express sebaceous material or the protrusion of a hair from the pit or punctum suggests the presence of a dermoid . The pits may not be noticed unless they have drainage or become infected. They may terminate near the skin surface but often extend deeply toward the cribriform plate (image 2).
Associated congenital anomalies, such as cleft defects, aural atresia, or hydrocephalus, have been reported in up to 41 percent of cases . The presence of associated anomalies increases the frequency of intracranial extension from 31 to 65 percent .
●Diagnostic imaging – The extent of the lesion is best determined by a combination of high-resolution axial and coronal computed tomography and magnetic resonance imaging (image 2 and image 3) [25-27]. The use of contrast may differentiate between dermoids, which are avascular, and enhancing lesions, such as hemangiomas or vascular teratomas .
●Surgical excision – Nasal dermoids with intracranial extension should be surgically excised because they increase the risk of central nervous system infection . Craniotomy, usually as a staged procedure, was classically necessary for the excision of nasal dermoids with intracranial extension . Minimally invasive endoscope-assisted approaches to the skull base combined with direct nasal incision or the open rhinoplasty approaches (ie, degloving the nose from tip to dorsum) have gained favor for lesions extending to the skull base or with minimal intracranial extension .
NASAL ENCEPHALOCELES — Similar to nasal dermoids, nasal encephaloceles result from congenital fusion abnormalities at the nasal root. Nasal encephaloceles are herniations of brain, meninges, and/or cerebrospinal fluid through a defect in the skull (image 4) . They communicate freely with the subarachnoid space and intracranial ventricular system. They occur in approximately 1 in 4000 live births and are thought to be caused by the defective closure of the anterior neuropore during the fourth week of embryogenesis . (See "Primary (congenital) encephalocele".)
Nasal encephaloceles may be frontoethmoidal (60 percent), basal (30 percent), or both (10 percent) [15,30]. Frontoethmoidal cephaloceles usually are evident at birth, presenting as a skin-covered mass at the root of the nose. Lesions that retain a connection with the subarachnoid space enlarge when the infant cries or strains. Basal cephaloceles are not apparent externally. They may cause nasal obstruction or symptoms related to the herniation of basal structures [15,30,31].
Surgical correction of nasal cephaloceles improves appearance and decreases the risk of developing meningitis . Cephaloceles typically are treated through a frontal craniotomy. The soft tissue and nose are approached only after dysplastic brain tissue is transected and a watertight closure of the dural defect is achieved . For limited lesions, transnasal anterior skull base approaches are possible and may be less morbid .
Neurologic outcome depends upon the extent of excision that is necessary. Normal mentation is possible after correction of pure meningoceles or small encephaloceles. In contrast, persistent neurologic deficits are common occurrences after excision of large portions of brain parenchyma.
NASAL GLIOMAS — Nasal gliomas are benign congenital tumors of ectopic glial tissue [35,36]. Their development is thought to be caused by faulty closure of the anterior neuropore. Most of these lesions arise from the lateral nasal wall and cause nasal obstruction . They typically appear in proximity to the skull base and must be differentiated from nasal dermoids, polyps, encephaloceles, and hemangiomas by distinctive computed tomography and magnetic resonance imaging features [15,37,38]. Biopsy and/or surgical excision should not be performed until the nature of the lesion is determined by computed tomography and magnetic resonance imaging . Surgical excision is the preferred treatment . Delayed therapy may result in infection or abnormalities of the septum and/or nasal bone.
PYRIFORM APERTURE STENOSIS — The pyriform aperture is the anterior bony opening of the nose in the facial skeleton. Congenital stenosis of this opening, known as congenital pyriform aperture stenosis (CPAS), may cause airway obstruction in newborn infants [20,39-41].
●Presentation – Infants with CPAS present with noisy breathing and respiratory distress that worsen with feeding and improve with crying [39,41]. CPAS may occur in isolation or in association with other anomalies, including single central maxillary incisor, pituitary abnormalities, craniosynostosis, and holoprosencephaly [20,42-46].
●Diagnostic imaging – The computed tomography finding of a small nasal opening confirms the diagnosis (image 5) and differentiates this malformation from choanal atresia and other causes of anterior nasal obstruction, including nasal mucosal edema, nasolacrimal duct cyst, or hypoplasia of the nasal alae . Computed tomography studies have also revealed that both the width of the nasal cavity and the pyriform aperture are narrowed [48,49]. Neuroimaging also may detect the presence of associated anomalies requiring intervention (eg, pituitary insufficiency). (See 'Choanal atresia' below and 'Nasolacrimal duct cyst' below.)
●Management – Nasal stenting with paired endotracheal tubes may be sufficient treatment for infants with mild stenosis. However, infants with severe stenosis may require tracheotomy to secure the airway until the child is large enough to tolerate the surgical enlargement of the pyriform aperture [42,50]. Even after surgical repair, the aperture may be relatively small, predisposing the child to developing upper airway obstruction during respiratory infection in the first years of life. Nasal dilation without bony removal or stenting is a potential alternative treatment option in patients with severe CPAS . In addition, neonatal rapid maxillary expansion as a treatment for this condition has been described in a case report .
Patients with congenital nasal pyriform aperture stenosis may become less symptomatic with age. One case series showed that after an initial period of rapid growth, pyriform aperture enlargement tends to be slower from 3.5 years to 6 years of age .
NASOLACRIMAL DUCT CYST — Nasolacrimal duct cysts (also called dacryocystoceles) are discussed separately. (See "Congenital nasolacrimal duct obstruction (dacryostenosis) and dacryocystocele", section on 'Dacryocystocele'.)
CONGENITAL MIDNASAL STENOSIS — Congenital midnasal stenosis is a relatively novel entity that has been described as a cause of nasal obstruction in newborns with choanae and nasal pyriform apertures of normal size. Diagnosis depends upon a high level of clinical suspicion and radiologic confirmation . Neonates typically present with nasal obstruction, stertor, and a nasal cavity that will not admit a 2.7-mm pediatric fiberoptic endoscope. In one series, computed tomography measurement of the narrowest width of the nasal cavity was significantly smaller than in control-group neonates .
Treatment consists of topical intranasal vasoconstrictors (eg, oxymetazoline) in the short term and longer applications of topical nasal steroids. In severe cases, nasal dilation with urethral sounds or balloon catheters has been employed with or without stenting .
CHOANAL ATRESIA — Choanal atresia is obliteration or blockage of the posterior nasal aperture. Choanal atresia often is associated with bony abnormalities of the pterygoid plates and midfacial growth abnormalities.
●Pathogenesis – One etiologic explanation for choanal atresia holds that persistence of the oronasal membrane prevents the joining of the nose and oropharynx. This theory does not account for the associated bony and midface abnormalities. An alternate explanation is that alterations in local growth factors result in small or imperforate choanae . Most cases involve bony and membranous obstruction to varying degrees (picture 7A-B).
●Presentation – The presentation of choanal atresia varies depending upon whether one or both sides are involved. Individuals with unilateral choanal atresia typically present later in life with unilateral nasal discharge and/or obstruction. Infants with bilateral choanal atresia typically present with upper airway obstruction, noisy breathing, or cyanosis that worsens during feeding and improves when the infant cries.
●Associated malformations and syndromes – Other congenital anomalies are present in 50 and 60 percent of individuals with unilateral and bilateral choanal atresia, respectively . Choanal atresia may occur as an isolated anomaly or as part of a multiple congenital anomaly syndrome (eg, Treacher Collins, CHARGE [coloboma of the iris or choroid, heart defect, atresia of the choanae, retarded growth and development, genitourinary abnormalities, and ear defects with associated deafness], Kallmann, VACTERL/VATER association [vertebral anomalies, anal atresia, cardiac defects, tracheoesophageal fistula and/or esophageal atresia, renal and radial anomalies, and limb defects], Pfeiffer) . (See "Syndromes with craniofacial abnormalities".)
Associated anomalies may include :
•Facial, nasal, or palatal deformities
•Congenital heart disease
•Coloboma of the iris and retina (picture 8)
•Malformations of the external ear
●Evaluation and diagnosis – The diagnosis should be suspected if a number 5 or 6 French catheter cannot be passed from the nose to oropharynx a distance of at least 32 mm . Qualitative measure of nasal airflow, such as the movement of a wisp of cotton under the nostrils or fogging of a mirror, adds support to the clinical diagnosis . Flexible or rigid nasal endoscopy can confirm the diagnosis by demonstration of a narrow or absent opening from the nasal cavity into the nasopharynx (picture 9).
The diagnosis of choanal atresia is confirmed by computed tomography with intranasal contrast that shows narrowing of the posterior nasal cavity at the level of the pterygoid plate (image 6).
In addition to a thorough physical examination to detect associated anomalies, cardiology and ophthalmology consultation are warranted for infants with choanal atresia.
●Management – Immediate management of infants with bilateral choanal atresia includes placement of an oral airway and initiation of gavage feedings .
Definitive repair involves transnasal puncture and stenting (picture 10) or endoscopic resection of the posterior nasal septum through a transnasal approach with or without stenting (picture 9) [60,61]. The transnasal puncture alone has fallen out of favor because of an unacceptable rate of recurrence [20,58]. Advantages of the transnasal endoscopic approach include clear vision of the operative field and accurate removal of the atretic plate and posterior vomerine bone without damage to surrounding structures . The classic transpalatal approach is reserved for difficult or recurrent cases (picture 11). Recurrent stenosis may occur even after successful surgery.
NASAL SEPTAL DEFORMITIES — Deformities of the nasal septum may be present at birth (image 7). These may be associated with other congenital midface anomalies, particularly cleft lip and palate , or may appear as isolated deformities. Anterior deviations in an otherwise well-formed nasal septum are thought to arise from intrauterine pressure effects or intrapartum trauma, which occurs more frequently in normal vaginal deliveries than following cesarean delivery .
Considerable controversy surrounds the necessity and timing of surgical repair of congenital nasal septal deformities . The nasal septum is a major growth center for the midface . There is evidence from animal experimentation  and serial clinical observations to suggest that disruption of this growth center may lead to maxillary hypoplasia. Given this information, any corrective surgery should aim for minimal disruption of normal growth centers.
Deviations of the nasal tip due to intrapartum pressure effects may resolve spontaneously. More significant nasal septal deformities may cause upper airway obstruction in infants because they are obligate nasal breathers. Under such circumstances, surgical correction in the first weeks of life may be necessary. Such surgery may involve intranasal stenting or manipulation of the cartilage of the nasal septum to return it to its normal position on the maxillary crest. Alternatively, conservative septoplasty with resection of fractured or deformed cartilages has been recommended by some authors in severe cases .
Rarely, portions of the anterior cartilaginous nasal septum or the posterior bony vomer may be congenitally absent [69,70].
SUMMARY AND RECOMMENDATIONS
●Arhinia, or absence of the nose, is a rare anomaly that is variably associated with absent paranasal sinuses, hypertelorism, microphthalmia, colobomas, nasolacrimal duct abnormalities, midface hypoplasia, high-arched palate, absent olfactory bulbs, and defects of the reproductive axis in males. Arhinia may cause neonatal respiratory distress at birth due to upper airway obstruction. (See 'Arhinia' above.)
●Supernumerary nostril is a rare malformation of the nose, characterized by an accessory, eccentric nasal opening, either connecting to the ipsilateral nasal cavity or terminating in a blind pouch. Surgical treatment usually consists of excision of the fistulous tract with plastic closure. (See 'Supernumerary nostril' above.)
●The holoprosencephalies are a group of midface and central nervous system malformations that result from improper segmentation and growth of the prosencephalon. The clinical manifestations range from an isolated single maxillary incisor to cebocephaly or cyclopia (picture 4 and image 1). Children with holoprosencephaly should be monitored for pituitary hormone deficiencies beginning in early childhood. (See 'Holoprosencephaly' above and "Overview of craniofacial clefts and holoprosencephaly", section on 'Holoprosencephaly'.)
●Frontonasal dysplasia (median cleft face syndrome) is characterized by hypertelorism, widow's peak (ie, V-shaped frontal hairline), cleft skull, and a median cleft of the upper lip and palate (figure 1). Associated ophthalmologic abnormalities are common. Evaluation by an ophthalmologist should be part of the initial management. (See 'Frontonasal dysplasia' above and "Overview of craniofacial clefts and holoprosencephaly", section on 'Craniofacial clefts'.)
●Nasal dermoids are epithelium-lined sinus tracts that extend from the root or tip of the nose through the nasal septum to the anterior cranial fossa (picture 6). The extent of the lesion is best determined by a combination of high-resolution axial and coronal computed tomography and magnetic resonance imaging. (See 'Nasal dermoids' above.)
●Nasal encephaloceles are herniations of brain, meninges, and/or cerebrospinal fluid through a defect in the skull (image 4). Those containing brain tissue are termed encephaloceles. They may communicate with the subarachnoid space and, occasionally, the ventricular system. (See 'Nasal encephaloceles' above.)
●Nasal gliomas are benign congenital tumors of ectopic glial tissue. Nasal gliomas must be differentiated radiographically from nasal dermoids, polyps, encephaloceles, and hemangiomas. (See 'Nasal gliomas' above.)
●Congenital pyriform aperture stenosis (CPAS) causes airway obstruction in newborn infants. Infants with CPAS present with noisy breathing and respiratory distress. These symptoms worsen with feeding and improve with crying. The computed tomography finding of a small nasal opening confirms the diagnosis (image 5). (See 'Pyriform aperture stenosis' above.)
●Nasolacrimal duct cysts (also called dacryocystoceles) are discussed separately. (See "Congenital nasolacrimal duct obstruction (dacryostenosis) and dacryocystocele", section on 'Dacryocystocele'.)
●Choanal atresia is obliteration or blockage of the posterior nasal aperture. Infants with bilateral choanal atresia typically present with upper airway obstruction, noisy breathing, or cyanosis that worsens during feeding and improves with crying. Patients with unilateral choanal atresia generally present later in life. The diagnosis is confirmed by computed tomography with intranasal contrast (image 6). Infants with choanal atresia should be evaluated for associated cardiac and ophthalmologic anomalies. (See 'Choanal atresia' above.)
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