A 38-year-old woman presented with a gradually increasing vulvar lump. Malignant lymphoma was suspected. No infiltrating tumor cells were observed in her blood or bone marrow, and PET revealed abnormal accumulation of cells only in the vulvar lesion. Histopathological examination showed invasion of tumor cells with small to medium nuclei and clumped chromatin in the dermis and fat tissue. Immunohistologically, the tumor cells were positive for myeloperoxidase, CD68, and CD117. The diagnosis was myeloid sarcoma. According to the recommended treatment for acute myeloid leukemia, the patient underwent chemotherapy, radiotherapy, and peripheral stem cell transplantation. However, her condition worsened and she died 3 years after the diagnosis.[Skin Cancer (Japan) 2017 ; 32 : 12-15]
