Herpes zoster oticus. The absence of grouped vesicles at any point during the eruption, itching rather than pain, and negative viral culture and polymerase chain reaction studies for herpes simplex and varicella zoster virus excluded the diagnosis of herpes zoster oticus.
Diagnostic criteria were met
This case was compatible with the characterizations of IED as initially described by Engman3 in 1902 and further detailed by Sutton,4 who provided the following criteria for diagnosis:
- an initial eczematous or pustular lesion
- extension peripherally by autoinoculation
- an absence of central clearing
- Staphylococcus on culture of the initial lesion
- a history of infection.
Case reports have added to our understanding of the mechanism of autosensitization of surrounding skin.5 Yamany and Schwartz have proposed the diagnostic criteria summarized in the TABLE.2
Age factors into location. The ears, nose, and face are predominantly involved in cases of IED in the pediatric population, while the lower extremities are predominantly involved in adults.6 Laboratory tests and imaging may aid in excluding other potential diagnoses or complications, but the diagnosis remains clinical and requires the clinician to avoid jumping to the conclusion that every moist, erythematous crusting eruption is purely infectious in nature.
Tx and prevention hinge on a combination of antibiotics, steroids
The management of IED should be aimed at fighting the infection, eliminating the allergic contact dermatitis associated with infectious products, and improving barrier protection. Topical and/or systemic antibiotics guided by culture focus on killing bacteria. The allergic immune response is dampened by systemic steroids. Topical steroids, however, are difficult to utilize on moist, draining skin. In the case of otitis externa, a combination topical antibiotic and steroid otic drop can be utilized. As healing begins, emollients are applied to aid in skin repair.2 Topical antibiotics containing neomycin or polymyxin should be avoided to eliminate the possibility of developing contact sensitivity to these agents.
For our patient, inpatient wound cultures demonstrated methicillin-resistant S aureus, and empiric treatment with IV cefepime and vancomycin was transitioned to IV clindamycin based on sensitivities and then transitioned to a 12-day course of oral clindamycin 150 mg bid. In addition, the patient received ciprofloxacin/dexamethasone otic drops 3 times/d to treat his otitis externa. After initiating prednisone 30 mg (1 mg/kg/d) for 10 days to cover the allergic component, the patient showed prompt clinical improvement. Gentle cleansing of the right ear with hypoallergenic soap and water followed by application of petrolatum ointment 4 times/d was used to promote healing and improve barrier function (FIGURE 2). The patient’s mother indicated during a follow-up call that the affected area had dramatically improved.
