Track

Case Reports

Abstract

An 85-year-old male presented with an occasionally pruritic eruption on the left chest and back that had been present for 4 months. Exam showed violaceous to orange agminated smooth papules and subtle vesicles in a dermatomal distribution over the left chest and back. Skin biopsy showed ill-defined granulomas with an interstitial pattern in the dermis, scattered multinucleated giant cells, and areas of elastophagocytosis. Areas of associated superficial fibrosis and scar were present. There was an associated perineural lymphoplasmacytic and focally granulomatous inflammatory infiltrate as well as lymphohistiocytic inflammation within the eccrine coils. In deeper sections there were remnants of a dilated follicular infundibulum with a surrounding mixed and granulomatous inflammatory infiltrate and with focal granulomatous inflammation within an arrector pili muscle. Overall, these findings were consistent with herpes zoster granulomatous dermatitis. The rash was then treated with a topical corticosteroid. Treatment with valacyclovir or gabapentin was not pursued given a lack of evidence of active infection.

The emergence of granulomatous dermatitis in regions previously affected by herpes zoster may occur weeks to years following acute infection. The pathogenesis of this eruption is not fully elucidated but has been previously attributed to Wolf’s isotopic response, referring to the occurrence of a new dermatosis at the site of another unrelated, already healed skin disease. However, recent data suggest that this eruption may be alternatively explained by remnant viral envelope glycoproteins that induce a persistent inflammatory reaction rather than an independent, new eruption occurring in old scars of herpes zoster.