Sweet syndrome with peripheral neuropathy in a patient with metastatic clear cell renal cell carcinoma.

A female patient in her 70s with a newly diagnosed clear cell renal cell carcinoma (ccRCC) with osseous metastasis presented with sudden onset erythematous painful blistering skin lesions on the dorsum of both hands, with associated intermittent fever episodes. Blood tests showed elevated inflammatory marker levels (C reactive protein 257.8 mg/dL, leucocytes 17.79×10⁹/L, with 94% neutrophils). Histologically, there was predominately neutrophil dermal infiltrate without leucocytoclastic vasculitis. The diagnostic criteria of Sweet syndrome were fulfilled. A week later, the patient developed abrupt left-hand palsy, which was confirmed as a medial and ulnar sensorimotor axonal peripheral neuropathy of paraneoplastic origin. The patient was prescribed a course of oral high-dose steroids, which significantly improved the skin lesions. The peripheral nerve palsy improved after 3 months. This case describes the two very rare concurrent paraneoplastic manifestations of ccRCC occurring simultaneously, which have been rarely reported.