Diagnosis of Neonatal Herpes Simplex Infection from the Placenta.

Due to a high rate of fetal demise and premature birth in intrauterine HSV infection, the outcome in neonates is usually adverse. A female preterm infant with a gestational age of 25 1/7 weeks with expected early clinical course tested positive for neonatal herpes simplex virus (HSV) 2 after the neonatologist was informed of positive immunohistochemistry for the virus on the fifth day of life by the pathologist. Pathological examination of the placenta had revealed subacute necrotizing inflammation with stromal cell necrosis suggestive of intrauterine infection, possibly ascending due to prolonged rupture of membranes. To the best of our knowledge, this is the first case wherein placental pathology indicated exposure to HSV before the infant presented with signs or symptoms of neonatal HSV resulting in a favorable outcome for the infant. Due to the variability of presentation of intrauterine HSV infection, pathological examination of the placenta in the first 2-5 days of life in premature infants can provide clues to the diagnosis of neonatal HSV which may significantly impact the outcome.