Infectious Disease · Viral Infections
The facts most likely to be tested
Primary orolabial herpes infection typically presents as gingivostomatitis with vesicular lesions on the oral mucosa and cervical lymphadenopathy in children.
Recurrent orolabial herpes manifests as herpes labialis (cold sores) characterized by a prodrome of burning, tingling, or itching at the vermilion border.
The gold standard diagnostic test for active lesions is PCR for HSV-1 DNA, which is more sensitive than viral culture.
Tzanck smear of a lesion scraping reveals multinucleated giant cells with intranuclear inclusions (Cowdry type A).
The virus remains latent in the trigeminal ganglia and reactivates due to triggers like ultraviolet light, stress, or immunosuppression.
First-line treatment for symptomatic orolabial herpes is oral valacyclovir or acyclovir, ideally initiated during the prodromal phase.
Erythema multiforme is a classic hypersensitivity reaction that can occur 1–2 weeks following an HSV outbreak, presenting with targetoid lesions.
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A 24-year-old male presents to the clinic with a painful cluster of small blisters on his lower lip. He reports that he felt a tingling and burning sensation in that area two days ago before the blisters appeared. On physical exam, there are grouped vesicles on an erythematous base at the vermilion border. He has no fever or systemic symptoms. He reports a similar episode last year after a beach vacation.
What is the most appropriate management for this patient?
Oral valacyclovir
The patient presents with recurrent herpes labialis; initiating oral antiviral therapy during the prodromal phase is the most effective way to reduce the duration and severity of the outbreak.
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Etiology / Epidemiology
Caused by HSV-1 via direct contact; primary infection often asymptomatic or gingivostomatitis.
Clinical Manifestations
Prodromal burning/tingling followed by grouped vesicles on an erythematous base.
Diagnosis
PCR is the gold standard; Tzanck smear shows multinucleated giant cells.
Treatment
Valacyclovir is first-line; avoid in severe renal impairment.
Prognosis
Virus remains latent in trigeminal ganglia; recurrence triggered by stress/UV light.
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Epidemiology & Etiology
Primary infection typically occurs in childhood via respiratory droplets or direct contact. HSV-1 is the primary pathogen, though HSV-2 is increasingly common due to oral-genital contact. Transmission occurs even during asymptomatic viral shedding.
Pertinent Anatomy
The virus establishes lifelong latency within the trigeminal ganglia. Reactivation travels down the sensory nerve axons to the mucocutaneous junction of the lips.
Pathophysiology
Initial infection involves viral replication in epithelial cells, causing cell lysis and inflammation. The virus then migrates via retrograde axonal transport to the sensory nerve root. Reactivation is triggered by UV light, immunosuppression, or emotional stress.
Clinical Manifestations
Primary infection often presents as herpetic gingivostomatitis with fever and painful oral ulcers. Recurrent outbreaks manifest as grouped vesicles on an erythematous base at the vermilion border. Red flags include ocular involvement (keratitis) or signs of herpetic whitlow on digits.
Diagnosis
PCR is the most sensitive and specific diagnostic test. A Tzanck smear of vesicle scrapings reveals multinucleated giant cells, though it lacks the sensitivity of PCR. Viral culture is rarely used due to low sensitivity.
Treatment
Initiate Valacyclovir within 48 hours of prodrome to shorten duration. Dose adjust for renal failure to prevent neurotoxicity. Topical agents are generally ineffective for established lesions.
Prognosis
Most cases are self-limiting within 7-10 days. Herpetic keratitis is a sight-threatening complication requiring urgent ophthalmology referral. Recurrence rates vary widely based on host immune status.
Differential Diagnosis
Aphthous ulcers: lack prodrome and vesicles
Impetigo: honey-colored crusts, not grouped vesicles
Hand-foot-and-mouth disease: involves palms and soles
Syphilitic chancre: painless, indurated ulcer
Erythema multiforme: targetoid lesions