Pseudoherpetic transient acantholytic dermatosis (Grover disease): case series and review of the literature.

A total of 3 cases of pseudoherpetic transient acantholytic dermatosis (Grover disease) are presented, followed by a brief review of prior reports. All 3 patients were above the age of 60 and presented with a pruritic eruption composed of papules with or without vesicles distributed on the trunk. For all 3 patients, the clinical differential diagnosis included drug eruption but did not include Grover disease; in 1 patient, the clinical impression included herpesvirus infection. Similar histologic and immunohistochemical findings were demonstrated in all 3 cases. Intraepidermal vesicles with acantholysis, multinucleation and hypereosinophilic keratinocytes mimicking necrosis raised the possibility of herpesvirus infection. However, the focality of the process at scanning magnification, absence of true cytopathic effect despite multinucleation, and identification of dyskeratosis rather than true necrosis all permitted for morphologic distinction as pseudoherpetic change. Immunohistochemistry, negative for herpes simplex virus and varicella zoster virus antigens, also distinguished pseudoherpetic change in these patients from a true herpesvirus infection. This series highlights an uncommon histologic variant of a common disorder and describes morphologic and immunohistochemical findings to facilitate its distinction from true herpesvirus infection.