De Morsier Syndrome Associated With Megalocornea: Impact of Hormone Replacement Therapy on the Resolution of Neonatal Cholestasis

De Morsier syndrome, or septo-optic dysplasia (SOD), is a rare congenital malformation characterized by optic nerve hypoplasia, midline brain abnormalities, and pituitary hormone deficiencies. Neonatal presentation can be misleading, particularly when it manifests as cholestatic jaundice. We report the clinical, biochemical, and radiological evaluation of a two-month-old male infant admitted for persistent neonatal cholestatic jaundice, progressive weight faltering, and recurrent hypoglycemia. Slit-lamp examination, comprehensive endocrine workup, and brain magnetic resonance imaging (MRI) were performed to establish the diagnosis. Written informed consent was obtained from the patient's parents (or legal guardians) for publication of this case report and any accompanying images. Physical examination revealed horizontal nystagmus and bilateral megalocornea (diameter > 13 mm). Laboratory investigations showed cholestasis with normal gamma-glutamyl transferase (GGT) levels and recurrent hypoglycemia, which led to the diagnosis of combined anterior pituitary hormone deficiency (growth hormone, thyroid-stimulating hormone, and adrenocorticotropic hormone). Brain MRI confirmed the diagnosis by showing agenesis of the septum pellucidum, bilateral optic nerve hypoplasia, and an ectopic posterior pituitary gland. Targeted hormone replacement therapy with L-thyroxine (10 μg/kg/day) and hydrocortisone (5 mg/kg/day) led to a complete resolution of the cholestasis within three weeks, alongside blood glucose stabilization and weight gain. Neonatal cholestasis is a classic early manifestation of SOD due to impaired bile acid transporter maturation caused by endocrine deficits. Its association with megalocornea highlights the variability of embryonic anterior segment anomalies. Early diagnosis is vital to initiate prompt hormone therapy, ensure hepatic recovery, and optimize neurodevelopmental outcomes.