Congenital Cytomegalovirus Pneumonitis Mimicking Childhood Interstitial Lung Disease: A Case Report and Review of Diagnostic Challenges.

We present a case of a full-term neonate with congenital cytomegalovirus (CMV) infection manifesting as severe pneumonitis. The patient exhibited intrauterine growth restriction (IUGR), early onset of respiratory distress, and persistent oxygen dependency. High viral load in urine and plasma supported the diagnosis, confirmed within the first three weeks of life. Despite treatment with oral valganciclovir for six months, persistent tachypnea, failure to thrive, and radiological findings prompted a broader differential diagnosis, including childhood interstitial lung disease (chILD). Bronchoscopy and whole-exome sequencing (WES) were performed. This case underscores the need for multidisciplinary evaluation in neonates with unexplained or protracted respiratory illness and highlights the potential overlap between congenital CMV pneumonitis and genetic interstitial lung disease (ILD).