DP10 Are all Sweet’s Sweet?

Abstract A 57-year-old woman was referred urgently to the hospital due to an uncommon pustular rash that had been present on her feet and hands (dorsum and palms) for 6 months, along with progressive suppuration changes on her hands. Despite being given topical steroids, she showed no improvement. She had no past medical history or skin issues, and no history of taking any regular drugs. However, she had smoked since the age of 18 years. Due to the atypical presentation a biopsy was taken from the dorsum and palmar aspect of the right hand in order to confirm the diagnosis. A dense intradermal neutrophilic infiltration was observed in the dorsal hand specimen associated with Sweet syndrome, while a dense intraepidermal neutrophilic infiltration was observed in the palm sample associated with palmoplantar pustulosis. In neither instance was there any indication of vasculitis. Baseline blood counts showed elevated neutrophils, C-reactive protein and total count. Based on these results, we concluded that the diagnosis was neutrophilic dermatosis of the dorsal hands (NDDH) and palmoplantar pustulosis (PPP) (Micallef D, Bonnici M, Pisani D, Boffa MJ. Neutrophilic dermatosis of the dorsal hands: a review of 123 cases. J Am Acad Dermatol 2023; 88: 1338–44; Misiak-Galazka M, Zozula J, Rudnicka L. Palmoplantar pustulosis: recent advances in etiopathogenesis and emerging treatments. Am J Clin Dermatol 2020; 21: 355–70). Our patient was started on topical steroids, a tapering dose of oral steroids and acitretin, following which the rash has improved. NDDH is an uncommon localized variant of Sweet syndrome, first described in 1995. Clinically, it presents with tender, erythematous plaques, pustules and bullae restricted to the dorsal aspects of the hands. In contrast, PPP is a chronic, recurrent disorder within the psoriasis spectrum that manifests as sterile pustules on the palms and soles. Histopathology is crucial for diagnosis, and while dermal neutrophilic infiltrates are observed in NDDH, intraepidermal neutrophilic infiltrates are observed in PPP. The simultaneous occurrence of NDDH and PPP in this patient raises intriguing questions regarding a potential shared immunological mechanism. While each condition has been individually documented in the literature, their concurrent occurrence in a single patient is exceptionally rare and raises questions about potential shared immunological and molecular pathways. This case represents the first documented instance of the coexistence of NDDH and PPP, underscoring the necessity for a high index of suspicion and a comprehensive diagnostic evaluation when faced with atypical or overlapping inflammatory dermatoses.