A Sweet-like syndrome manifesting as gingival hyperplasia and myositis without cutaneous involvement

Sweet's syndrome or acute febrile neutrophilic dermatosis, characterized by fever, neutrophilia, and focal infiltration of the dermis was originally described after episodes of infection. It is also known to occur in acute myeloid leukemia. A patient with acute myeloid leukemia (AML M3) developed gingival hyperplasia and muscle swelling and tenderness after starting treatment with all- trans retinoic acid. Microscopic examination showed neutrophilic infiltrate. All cultures were sterile. The lesions did not respond to cytotoxic therapy and continued to persist even after achievement of remission. The response was seen only after prednisolone was started. This case highlights the fact that a Sweet-like syndrome can occur without the characteristic cutaneous lesions and in such situations there can be considerable diagnostic and therapeutic difficulty.