Arhinia

Arhinia refers to congenital failure of the external nose, nasal cavity, and olfactory apparatus to develop. It is an extremely rare condition that can be detected on prenatal ultrasound or MRI.

Epidemiology

Arhinia may occur in a syndromic setting (such as ethmocephaly), but it has been reported to occur sporadically.

Pathology

Results from a fetal insult at 3-8 weeks gestational age.

Radiographic features

Absence of the soft tissues of the nose can be detected on a second trimester ultrasound study and confirmed with fetal MRI, if desired. Midfacial flattening of the facial profile and a prominent upper lip can be seen .

Arhinia is associated with other midface anomalies, such as hypo- or hypertelorism. It has also been associated with other anomalies such as syndactyly and hypospadias .

Both partial arhinia and total arhinia have been reported.

Treatment and prognosis

Treatment involves managing the nasal cavity airway and managing subsequent feeding difficulties. Surgical reconstruction can be performed at a later date.

Differential diagnosis

Arhinia is different than a hypoplastic or absent nasal bone, which is a marker for trisomy 21.