Congenital nasal pyriform aperture stenosis in the monozygotic twin of a child with holoprosencephaly.

Abstract C ongenital nasal pyriform aperture stenosis (CNPAS) is a recently defined clinical entity that causes airway obstruction in the neonate as a result of narrowing of the nasal pyriform aperture. The first description of nasal pyriform aperture stenosis (NPAS) was in 1952 by Douglas, 1 who reported a series of eight affected adults, most of whom also had a cleft lip. In 1989 Brown et al. 2 described six infants with CNPAS, all of whom lacked other congenital anomalies. They explained that CNPAS represents a bony overgrowth at the inferior aspect of the pyriform aperture and can occur either as an isolated abnormality or as part of a group of abnormalities. They also provided the first management recommendations for this condition. In 1992 Arlis and Ward 3 reported six patients with CNPAS, four of whom had a single prominent maxillary incisor. Thus, because of the known association of a single central incisor with holoprosencephaly (HPE), 4 they hypothesized that CNPAS may represent part of the HPE spectrum. 3