A rare presentation of pemphigus vegetans as an isolated vegetative lesion—Review of histopathological clues and treatment effects in multiple biopsy specimens

Pemphigus is a group of immunobullous dermatoses characterized by the presence of autoantibodies directed against adhesion molecules of keratinocytes, with pemphigus vegetans being the rarest form, accounting for 1%-2% of all cases of pemphigus. Pemphigus vegetans is characterized by verrucous vegetative lesions in addition to vesiculobullous lesions.We report a rare case of pemphigus vegetans presenting as an isolated vegetative lesion in the groin 3 months prior to the development of blisters. Owing to the atypical presentation, multiple biopsies were performed before and after corticosteroid treatment.Comparing the histopathology of pre-treatment and post-treatment biopsy specimens, the resolution of intraepidermal microabscesses, and reduction in intraepidermal and dermal inflammatory infiltrates, spongiosis and interface change, attributable to treatment, were noted. However, direct immunofluorescence showed persistent intracellular intraepidermal deposition of IgG and C3 2 weeks into treatment, despite near-complete resolution of blisters on clinical examination. Clinical regression of the vegetative lesion was noted only after 6 weeks into corticosteroid treatment, while histopathological evidence of treatment was apparent at the second week.The current case illustrates the importance of a liberal use of immunofluorescence studies in establishing the uncommon yet significant diagnosis of pemphigus vegetans, particularly for vegetative lesions that are persistent, in the intertriginous areas and/or in the setting of concurrent cutaneous or mucosal symptoms.