Two cases of reactive perforating collagenosis arising at the site of healed herpes tester

Case 1 A 67-year-old South Korean woman presented with a painful eruption o n the left trunk. Several groups of vesicles with an erythematous and edema tous base were situated unilaterally within the distribution of the left T9 dermatome; they had been present for 7 days. A diagnosis of herpes tester was made, and treatment with acyclovir, analgesics, tranquilizers, and wet dressings produced a moderate response. Two weeks after onset, the lesions appeared to have healed with a scar. Four months later. however, the patien t noticed another eruption of papules in the postherpetic area (Fig. 1A,B). The biopsy specimen showed a cup-shaped epidermal invagination filled with a keratotic , plug containing basophilic debris and collagen, with perforat ion of the epidermis. Masson's trichrome stain identified refractile fibers within the epidermis as hyalinized and degenerating collagen. Van Gieson s taining for elastic fibers was negative in the epidermis and in the crater. These findings are consistent with reactive perforating collagenosis (RPC) . Case 2 A 66-year-old South Korean woman developed herpes tester of the le ft neck and shoulder, which resolved after an uncomplicated course. Two mon ths later, a zosteriform, pink, papular eruption developed at the site of t he resolved herpes tester. Examination revealed multiple, erythematous papu les with a central umbilication containing a firmly adherent keratotic plug on the left shoulder and neck (Fig. 2A). The biopsy specimen showed a dome-shaped lesion with a central crater that extended from the epidermis to the papillary dermis and contained degenerat ed collagen in vertical strands (Fig. 2B).