A clinical diagnosis quandary: herpes zoster ophthalmicus versus paederus dermatitis

Abstract

Background: Herpes zoster ophthalmicus (HZO) and Paederus dermatitis (PD) may present with overlapping dermatological features, leading to diagnostic challenges.

Case report: A 15-year-old boy presented with a one-week history of right eye pain, swelling, and fever, accompanied by vesicular lesions distributed along the right V1 and V2 dermatomes, respecting the midline. He reported a Paederus fuscipes bite in the right cheek two days before symptom onset. Examination revealed conjunctival chemosis, mechanical ptosis, restricted extraocular motility, and a grade 1 relative afferent pupillary defect. Imaging showed preseptal cellulitis with facial extension and lacrimal gland abscess. Treatment comprised oral acyclovir, intravenous ceftriaxone, intravenous metronidazole, and topical chloramphenicol ointment, with gradual improvement in systemic, ocular, and dermatological findings, and restoration of optic nerve function.

Conclusion: The clinical overlap between HZO and PD emphasizes the importance of a thorough clinical assessment—including dermatome pattern recognition, ocular examination, and systemic symptoms—to guide appropriate treatment.