Palisaded neutrophilic granulomatous dermatitis: Spectrum of histologic findings in a single patient

GA: granuloma annulare PNGD: palisaded neutrophilic granulomatous dermatitis RA: rheumatoid arthritis INTRODUCTION Palisaded neutrophilic granulomatous dermatitis (PNGD) is a typically associated with underlying disease states, including autoimmune connective tissue disease, lymphoproliferative disorders, and infections. Although most common in patients with rheumatoid arthritis (RA), PNGD can also be seen in patients with systemic lupus erythematosus and systemic vasculitides. Clinically, PNGD presents with tender, erythematous-to-violaceous papules, plaques, or nodules affecting the extensor surfaces. Acral, including palmar, involvement is characteristic, and umbilicated papules overlying bony prominences are also described. Histologically, early lesions of PNGD present with neutrophilic infiltrates and leukocytoclastic vasculitis; fully developed lesions feature palisaded granulomas with collagen trapping and neutrophil remnants. Given the wide range of clinical features, histopathologic findings, and underlying systemic diseases, the diagnosis of PNGD can be challenging, requires careful clinicopathologic correlation, and relies on knowledge of the varying histologic findings. Here, PNGD with underlying RA in a single patient with 3 distinct histopathologic patterns is presented.