Congenital nasal pyriform aperture stenosis, single central maxillary incisor and ectopic posterior pituitary gland

Clinical History

A female neonate presented shortly after birth with respiratory distress and noisy breathing. The introduction of an intra-nasal catheter was difficult. Due to the presence of respiratory distress and inability to feed, immediate surgery was indicated. Hormonal investigation showed central hypothyroidism, growth hormone and corticotropin deficiency, and normal posterior pituitary function.

Imaging Findings

CT demonstrated the presence of marked stenosis in both pyriform apertures due to overgrowth of the nasal process of the maxilla and a single maxillary incisor (Figures 1, 2).
Brain MRI preformed to evaluate the presence of concomitant CNS abnormalities revealed an ectopic position of the posterior pituitary gland at the median eminence, a hypoplastic anterior pituitary and a thin continuous pituitary stalk (figure 3, 4).

Discussion

Congenital nasal pyriform aperture stenosis (CNPAS) is a rare condition that causes airway obstruction in the newborn, first described in 1989 [1]. It is caused by an overgrowth of the nasal process of the maxillar during embryogenesis, reducing the anterior part of the nasal cavity [1-3]. Abnormal bony overgrowth can cause varying degrees of nasal airway obstruction resulting in respiratory difficulty with cyclic cyanosis, relieved by crying. The clinical symptom of the CNPAS resembles that of the posterior choanal atresia [1, 2]. However, CNPAS must be distinguished from the choanal atresia, which causes a reduction of the posterior part of the nasal cavity [2, 3]. On nasal examination, there is a bone protruding medially at the area of limen vestibule and the passing of a catheter is difficult.
Initially, the occurrence of the CNPAS was thought to be an isolated nasal anomaly but later studies revealed its association with other craniofacial or CNS abnormalities and particularly with a single central maxillary mega incisor (SCMI)[4-7]. A SCMI can be detected in up to 60% of CNPAS cases [4-7]. CNPAS is now considered to be a manifestation of a broader developmental field defect known as holoprosencephaly (HPE) [4, 5]. HPE is a dysgenesis of the prosencephalon resulting in abnormal or non-separation of the forebrain into cerebral hemispheres. Midline facial structures are often affected as well. Facial anomalies range in severity from anophthalmia, cyclopia, ethmocephaly, flat nasal bridge, maxillary agenesis, absent frenulum, medial cleft lip, or a SCMI [4, 5]. Individuals with these specific mild facial malformations without CNS abnormalities may represent “microforms” or part of the HPE spectrum. Nowadays, CNPAS and SCMI represent “microforms” of HPE.
Abnormalities of the hypothalamo-pituitary (HP) axis and endocrine dysfunction are frequently reported in children with CNPAS. Endocrine dysfunction (hypopituitarism and diabetes insipidus) is observed in 56% of the patients with HP axis abnormalities on MRI while a normal HP axis on MRI is highly predictive of normal endocrine function [8, 9]. Ectopic neurohypophysis is the most frequent abnormality seen on MRI [8, 9].
In conclusion, CNPAS is an anterior nasal obstruction that should be included in the differential diagnosis of congenital nasal airway obstruction in infancy. The association with findings of holoprosencephaly and pituitary gland abnormalities should always be taken into account when managing children with CNPAS. It is essential to always check for abnormalities of the HP axis in order to prevent the development of clinical signs due to endocrine dysfunction.

Differential Diagnosis List

Final Diagnosis

Congenital nasal pyriform aperture stenosis, single central maxillary incisor and ectopic posterior pituitary gland

URL:	https://eurorad.org/case/12963
DOI:	10.1594/EURORAD/CASE.12963
ISSN:	1563-4086