History
A 10-year-old boy presents to the accident and emergency department with a 7-day his-tory of a blister, which appeared on his lower lip with subsequent crusting and is now spreading over the right side of his cheek. He complains of pain in his mouth, lip and right side of his face, which feels swollen. He is initially referred to the maxillary-facial team with a suspected dental abscess. An orthopantomogram X-ray is normal; he is then referred to the on-call dermatology team. He reports an allergy to erythromycin.
Examination
He has tense blistering and erythematous crusted lesions on his right lower lip and cheek (Fig. 74.1). There is erythema that has golden crusting with vesiculation particularly on his lower lip. He has tender lymphadenopathy in the supraclavicular region. Inside his mouth there is no evidence of a dental abscess.
Questions
• What is the most likely diagnosis?
• What secondary cutaneous complica-tion has arisen?
• How would you manage this patient acutely and in the future?
Medicine
When any patient presents with a blistering eruption on the lip, the most likely diagnosis is herpes simplex virus (HSV), usually type I. Patients may describe a prodrome of tin-gling and pain 24–48 hours prior to the onset of blistering. Although the lip is the most common site (herpes labialis), lesions of HSV can occur at other mucous membrane sites (nose and genitalia, usually type II), or indeed anywhere else on the skin.
Primary HSV is usually asymptomatic, however in a small minority of patients the initial infection can be very severe and extensive. Subsequent attacks occur due to reactiva-tion of the life-long persistent HSV, which stays within the dorsal root ganglion of the affected nerve. Attacks of so-called ‘cold-sores’ can occur at intervals, usually at the same mucous membrane/skin site. Triggers include cold weather, bright sunlight, immunosup-pression, intercurrent illness, trauma and high altitude.
The differential diagnosis of blistering on the lips includes primary impetigo, burn/trauma, hand-foot and mouth, erythema multiforme major, Stevens–Johnson syndrome, toxic epidermal necrolysis, fixed drug eruption, immunobullous disease and porphyria. The history, clinical signs and investigations should, however, help to distinguish HSV from these other diagnoses.
This patient suffered a HSV type I infection of the right lower lip and subsequently developed secondary impetigo due to Staphylococcus aureus (an ‘aureus’ was a goldn coin issued in Rome in the first century BC). Secondary bacterial infection is particularly common with HSV infections and is characterized by golden crusted areas on the skin.
Antibacterial washes containing low concentrations of chlorhexidine (Dermol®) are help-ful in clearing mild, localized skin infections. Topical (fucidin) or oral antibiotics (flu-cloxacillin, erythromycin) are required in some cases.
Swabs that were sent to the laboratory in viral transport medium confirmed the presence of HSV type I DNA. If patients present within 72 hours of the onset of HSV infections, then a course of oral aciclovir is helpful. Patients can purchase topical aciclovir over the counter, which can be effective in mild attacks if treated early. Patients developing recurrent symptomatic attacks may benefit from secondary prophylaxis with aciclovir 400 mg daily, other patients may prefer to have some aciclovir tablets at home to take immediately they become symptomatic with the prodrome/blisters.
KEY POINTS
• Herpes simplex virus (HSV) reactivation is usually preceded by a cutaneous prodrome of tingling and pain.
• Recurrent attacks of blistering affecting a mucous membrane site are likely to be caused by HSV.
• Patients suffering from recurrent attacks of reactivation may require secondary prophy-laxis with aciclovir.
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