Palisaded neutrophilic and granulomatous dermatitis presenting in a patient with hidradenitis suppurativa on infliximab

Summary: Abstract Body: To describe a case of PNGD associated with infliximab therapy in a patient with HS and present relevant clinical and histopathological findings. Hidradenitis suppurativa (HS) is a chronic, debilitating skin disorder involving follicular biology, often treated with a combination of antibiotics, anti-androgen, and anti-inflammatory therapy. Tumor necrosis factor-alpha (TNF-α) inhibitors, such as infliximab, are well-tolerated options for patients with inflammatory lesions, tunnels, and scarring who fail to achieve disease control with conventional therapies1. However, TNF-α inhibitors can paradoxically trigger adverse cutaneous reactions, including palisaded neutrophilic and granulomatous dermatitis (PNGD)2. A 26-year-old African American female with a 13-year history of HS presented to our dermatology center for management. Shortly after initiating infliximab therapy, the patient developed eruptive, monomorphic flesh-colored papules involving the face, anterior trunk, and proximal upper extremities. After 3 months, a 4.0-mm punch biopsy of a representative lesion on the on the shoulder revealed ischemic-driven necrobiosis with palisading histiocytes, consistent with a rheumatoid nodule. Ischemic-driven necrobiosis with palisading granulomatous inflammation, resembling rheumatoid nodules, is a recognized, paradoxical complication of TNF-α inhibitor therapy.2,4,5 This auto-inflammatory reaction may result from downregulation of T-regulatory cell activity, contributing to neutrophilic and granulomatous inflammation. While PNGD is well-documented in patients with rheumatoid arthritis receiving TNF-α blockade,3 this case highlights its occurrence in the setting of HS treated with infliximab. This case underscores the importance of identifying paradoxical cutaneous reactions, such as PNGD, in HS patients undergoing TNF-α inhibitor therapy. Further studies are needed to elucidate the underlying immunopathogenesis and guide management in such cases. Khyla Hill¹, Steven Cohen¹, Hansen Tai¹, Aarthi Parvathaneni¹ 1. Dermatology, Weill Cornell Medicine, New York, NY, United States. Translational Studies: Cell and Molecular Biology