[Risk factors for disseminated herpes zoster]

When skin abnormalities in patients extend over several dermatomes, disseminated herpes zoster should be suspected. This complication is most often seen in immunocompromised patients.

An 87-year-old patient came to the dermatology outpatient clinic with several vesicles scattered over her body. She was being treated with methotrexate for rheumatoid arthritis. Upon physical examination, we found groups of vesicles in the area of the maxillary nerve as well as several solitary vesicles scattered over her body. We made the diagnosis of 'disseminated herpes zoster'. PCR test of fluid from one of the vesicles found Varicella zoster virus. We treated the patient with intravenous acyclovir for 48 hours after which we treated her with oral acyclovir for another 8 days. We temporarily halted methotrexate. Outpatient follow-up found that the patient's skin abnormalities had diminished significantly.

The risk of disseminated herpes zoster depends on several factors. Use of immunosuppressants is often not the only contributing factor. Risk of disseminated herpes zoster in a patient who is being treated with methotrexate depends on age, comorbidities and co-medication of the patient.