Arhinencephaly

This code describes arhinencephaly, a rare congenital malformation characterized by the absence of the rhinencephalon, which includes the olfactory bulbs and tracts. This condition is often associated with other midline facial defects and brain abnormalities, indicating a failure of forebrain development.

Assign this code when documentation explicitly states a diagnosis of arhinencephaly. This diagnosis is typically made prenatally via ultrasound or MRI, or postnatally based on clinical examination and neuroimaging findings. Supporting documentation should clearly identify the absence of olfactory structures.

• Differentiate from other forebrain anomalies such as holoprosencephaly, which may present with similar features but involve more extensive brain malformations.
• Always review imaging reports (e.g., fetal MRI, postnatal brain MRI) for definitive diagnostic confirmation.
• Consider co-occurring congenital anomalies and code them appropriately, as arhinencephaly rarely occurs in isolation.