Tehran University of Medical Sciences International Journal of Hematology-Oncology and Stem Cell Research 2008-2207 19 3 2025 07 21 286 290 EN Atefeh Rezaee Ahvaz Jundishapur University of Medical Sciences, Thalassemia and Hemoglobinopathy Research Centre, Health Research Institute, Ahvaz, Iran Tina Vosoughi Ahvaz Jundishapur University of Medical Sciences, Thalassemia and Hemoglobinopathy Research Centre, Health Research Institute, Ahvaz, Iran Mehran Hosseinzadeh Ahvaz Jundishapur University of Medical Sciences, Thalassemia and Hemoglobinopathy Research Centre, Health Research Institute, Ahvaz, Iran Mohammad Hossein Rastegar Ahvaz Jundishapur University of Medical Sciences, Thalassemia and Hemoglobinopathy Research Centre, Health Research Institute, Ahvaz, Iran 2024 04 16 2025 05 03 Sweet's syndrome is a rare dermatological condition characterized by a constellation of clinical features, including fever, neutrophilic leukocytosis, painful skin plaques, and dermal neutrophil infiltration. Various etiologies have been documented, encompassing both underlying diseases and pharmacological agents. We present a case involving a 35-year-old female patient who exhibited fever and progressive cutaneous lesions manifesting as a painful erythematous rash on the limbs and trunk. Initially misdiagnosed as seronegative lupus erythematosus, her condition did not improve. A skin biopsy revealed significant neutrophilic infiltration, and she subsequently developed leukocytosis, leading to a diagnosis of acute leukemia upon bone marrow examination. The patient was treated with chemotherapy, resulting in a relative improvement of her skin lesions. https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/view/2223 https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/download/2223/1093