Neonatal Vesicles with a Febrile Mother
A 9-day-old term boy, born by spontaneous vaginal delivery, is brought with clusters of 2–4 mm tense vesicles on an erythematous base over the left cheek and chin, present since day 6. He is feeding poorly today and feels warm. Mother reports a 'cold sore' on her lip that appeared 3 days after delivery; she has not been examined. Temperature is 38.1°C, heart rate 168/min, and the infant is irritable but consolable. A Tzanck smear from a vesicle shows multinucleated giant cells. You are the dermatology consultant called by the pediatric team at 22:00 in a hospital without a virology laboratory overnight.
1. What is your leading diagnosis and immediate management plan? Justify each step and state what you would NOT do.
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Leading diagnosis: neonatal herpes simplex virus (HSV) infection, most likely HSV-1 acquired perinatally or postnatally from maternal labial lesions, presenting as skin-eye-mouth (SEM) disease but with systemic features (fever, poor feeding, tachycardia) that raise concern for disseminated or CNS involvement.
Immediate steps (do not wait for confirmation):
- Admit and start IV high-dose acyclovir (20 mg/kg every 8 h in neonates) empirically - neonatal HSV is a time-critical emergency; mortality and morbidity in disseminated/CNS disease depend on how early therapy starts.
- Full sepsis evaluation before or alongside antivirals: surface swabs from vesicles, conjunctivae, nasopharynx and rectum for HSV PCR/culture; blood HSV PCR; lumbar puncture with CSF HSV PCR (and cell count/protein/glucose) - CNS disease can occur with normal CSF early; LFTs and CBC.
- Empirical antibacterial cover per neonatal sepsis protocol until cultures are back, since bacterial sepsis cannot be excluded clinically.
- Eye and mouth examination for keratitis and oral lesions; ophthalmology review.
- Infection control: cohort nursing, contact precautions; examine and swab the mother's lip lesion; counsel her on hand hygiene and avoiding kissing the infant.
What I would NOT do: deroof or biopsy the vesicles for diagnosis when a Tzanck smear plus PCR swabs suffice; apply topical antivirals as sole therapy; delay IV acyclovir for imaging; or reassure on the basis of a 'benign' Tzanck result - multinucleated giant cells support HSV but do not exclude serious disease.
2. The CSF PCR returns negative at 48 h and the infant is afebrile but still has new vesicles. How does this change management, and how long should treatment continue?
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Interpretation: a negative CSF PCR at 48 h reduces but does not exclude CNS disease - sensitivity is highest in the first 72 h and can be falsely negative with early sampling or low viral load. Persisting new vesicles indicate ongoing viral replication and inadequate control, not a benign course.
Management:
- Continue IV acyclovir at treatment dose; do not step down to oral therapy while new lesions appear.
- Repeat lumbar puncture if neurological signs develop or if the initial tap was traumatic; consider repeat CSF PCR at 72–96 h in the presence of new vesicles.
- Reassess for disseminated disease: repeat LFTs, CBC, and check for pneumonitis; consider abdominal imaging if hepatitis is suspected.
- Exclude bacterial superinfection of vesicles and review antibacterial therapy.
Duration: for SEM disease without CNS involvement, IV acyclovir for 14 days; for CNS or disseminated disease, 21 days with a repeat CSF PCR at the end of therapy to guide stopping. Since CNS disease is not definitively excluded, I would treat for at least 14 days and extend to 21 days if any CNS/disseminated features emerge. Suppressive oral acyclovir for 6 months after the neonatal course reduces recurrences and improves neurodevelopmental outcome and should be discussed with the family.