Palisaded neutrophilic and granulomatous dermatitis, A critical diagnosis in a severe lupus flare

Palisaded Neutrophilic And Granulomatous Dermatitis (PNGD) is a rare inflammatory cutaneous eruption associated with underlying systemic disease, commonly Systemic Lupus Erythematosus (SLE), rheumatoid arthritis, or Anti-Neutrophilic Cytoplasmic Autoantibody (ANCA)-associated vasculitis. Appropriate diagnosis is challenging, requiring coordination of care between medicine, dermatology, pathology, and rheumatology. We describe a 29-year-old female with SLE who developed eroded papules and erythematous, edematous plaques on the ear anti-helices, hands, and elbows during hospitalization for workup of acute on chronic abdominal pain. Biopsies showed an interstitial infiltrate of zonal collagen necrobiosis, consistent with typical PNGD histopathology, involving collagen inflammation surrounded by palisading neutrophils, histiocytes, karyorrhexis, and leukocytoclastic vasculitis. The association of ANCA-vasculitis makes differentiation between underlying autoinflammatory disease in PNGD from new vasculitis difficult; however, histopathology is key to distinguishing them. Treatment should focus on improvement of the underlying autoimmune condition. Adjuvant treatments are intralesional or systemic corticosteroids, hydroxychloroquine, or dapsone. Given the complexities of associated conditions, it is important to bring awareness of PNGD to the medical community for improved diagnostic accuracy and subsequent care.