A case of filgrastim-induced neutrophilic dermatosis of the dorsal hands in a patient with Felty Syndrome.

Neutrophilic dermatosis of the dorsal hands (NDDH) is a variant of Sweet syndrome that presents with erythematous bullae, papules/plaques, or pustules on the dorsal hands. It is most commonly associated with hematologic and solid organ malignancies, though cases of NDDH associated with inflammatory bowel disease, rheumatologic disorders, and medication exposure have also been described in the literature. Felty syndrome is a rare complication of long-standing rheumatoid arthritis characterized by neuropathy, splenomegaly, and neutropenia. Granulocyte colony stimulating factors (e.g., filgrastim) can be utilized to rescue the neutropenia observed in Felty syndrome, but this treatment may subsequently cause Sweet syndrome. Herein, we present a 64-year-old man with Felty syndrome and a complex medical history who presented with sudden onset, painful blisters located on the dorsal and palmar aspects of his bilateral hands. Given the patient's past medical history, a broad differential diagnosis, including disseminated fungal and viral infection was initially considered. A punch biopsy of the skin lesion disclosed neutrophilic dermatosis, which together with laboratory data satisfied the von den Driesch criteria for Sweet syndrome. As the lesions were localized exclusively on the patient's hands, the qualification of NDDH was also endorsed.