Case Report: Cytomegalovirus-associated granulomatous lung disease in an immunocompetent preterm infant.

Granulomatous lung disease caused by cytomegalovirus (CMV) has not been described in immunocompetent infants. We report a 5-month-old boy, born at 31+5 weeks of gestation, with a 2-month history of isolated cough and normal growth. Contrast-enhanced chest computed tomography showed a multiloculated cystic mass in the right upper lobe. CMV DNA was detected in whole blood (1.41 × 104 copies/mL) and urine (1.44 × 106 copies/mL). Intravenous ganciclovir for 2 weeks produced no radiological change; because a tumor could not be excluded, video-assisted thoracoscopic right upper lobectomy was performed. Histology showed extensive necrosis with well-formed epithelioid granulomas and multinucleated giant cells. Stains for acid-fast bacilli and fungi and Epstein-Barr virus-encoded RNA in situ hybridization were negative. To exclude an infectious granulomatous disease, metagenomic next-generation sequencing (mNGS) of the resected tissue identified CMV at 1,143 reads per million as the only pathogen. The postoperative course was uncomplicated, with no recurrence at 6 months. CMV produced a localized granulomatous mass mimicking a congenital lung lesion or neoplasm, and tissue mNGS provided the decisive microbiological evidence. When a preterm infant has an unexplained chronic pulmonary lesion, CMV should be considered, and mNGS of pathological tissue can establish the diagnosis.