Fatal Deterioration of a Respiratory Syncytial Virus Infection in an Infant with Abnormal Muscularization of Intra-Acinar Pulmonary Arteries: Autopsy and Histological Findings.

Respiratory syncytial virus (RSV) infection represents a global and noteworthy cause of hospitalization and death in infants of less than 1 year of age. The typical clinical manifestation is bronchiolitis, an inflammatory process of the small airways. The symptoms are usually a brief period of low-grade fever, cough, coryza, breathing difficulties, and reduced feeding. The progression of the disease is difficult to predict, even in previous healthy subjects. Symptoms may also be subtle and underestimated, thus leading to sudden unexpected infant death (SUID). In these cases, RSV infection is discovered at autopsy, either histologically or through real-time reverse transcription polymerase chain reaction (RT-PCR) performed on nasopharyngeal swabs. Herein, we describe a case of RSV infection in a 6-month-old infant with no risk factors, who rapidly deteriorated and unexpectedly died of respiratory insufficiency in a hospital setting. RT-PCR on nasopharyngeal swabs revealed RSV. The autopsy showed diffuse lymphogranulocytic bronchitis and bronchiolitis, and multiple foci of acute pneumonia. Abnormal muscularization of the intra-acinar pulmonary arteries was also observed, which likely contributed to worsening the lung impairment.