RESUMEN
Sweet's syndrome is characterized by a combination of clinical and pathologic findings including fever, neutrophilia, tender erythematous skin lesions, and a diffuse infiltration of mature neutrophils in the upper dermis. Numerous diseases and clinical manifestations have been associated with the disease; however, Sweet's syndrome associated with subdermal cystic skin lesions and arthritis is rare. A 71-year-old female patient presented with fever, erythematous plaques, multiple hypoglossal ulcers, and arthritis in both ankles. The skin lesions were variously sized areas of erythematous swelling on the forehead, back, and left shoulder. Musculoskeletal sonography revealed hypervascularity and a subdermal cyst in the erythematous plaque on her back. The results of a skin biopsy indicated the presence of mature neutrophilic infiltration in the dermis and thus led to the diagnosis of Sweet's syndrome. We herein present an unusual case of Sweet's syndrome presenting as erythematous subdermal cystic lesions, multiple hypoglossal ulcers, and bilateral ankle arthritis with a literature review.