ABSTRACT
Anti-melanoma differentiation-associated gene 5 (MDA5) dermatomyositis is characterized by serological detection of anti-MDA5 antibody and rapidly progressive interstitial lung disease. In this study, the largest cohort of skin biopsies to date of anti-MDA5 dermatomyositis was reviewed and compared with cases of dermatomyositis with negative serology. Findings contribute to the histological diagnosis and evaluation of the severity of cutaneous inflammation in anti-MDA5 dermatomyositis. Skin biopsies collected over a 7-year period from individuals with clinically and histologically confirmed dermatomyositis with anti-MDA5 serology were reviewed. A total of 46 cases with 17 anti-MDA5 positive cases were retrieved. Patients with positive antibody were younger (53.7 vs. 60.6 years, p = .013). No differences in epidermal changes (p > .05) were observed. Pertaining to interface changes, anti-MDA5 dermatomyositis showed a higher degree of pigmentary incontinence (p = .014), suggesting increased and sustained cutaneous inflammation. Periodic acid-Schiff (PAS) stain demonstrated a greater degree of basement membrane thickening (p = .045). Other parameters, including dermal inflammation, dermal mucin deposition and vasculitic/vasculopathic features did not show statistical difference between anti-MDA5 positive and negative dermatomyositis (p > .05). Findings suggest increased cutaneous inflammation for anti-MDA5 dermatomyositis. In skin biopsies, marked pigmentary incontinence or basement membrane thickening should raise suspicion of anti-MDA5 dermatomyositis.
ABSTRACT
BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
