An 87-year-old woman with a 2-cm left vulvar mass was initially treated with antibiotics due to a suspicion of Bartholin's gland abscess. The mass grew rapidly, from 2 cm to 10 cm, within 3 months. Biopsy showed a diffuse large B cell lymphoma. After one cycle (5 days) of treatment with 200 mg endoxan and 60 mg prednisolone, the vulvar mass significantly decreased in size within two days after beginning treatment, and completely resolved seven days later. We concluded that if a vulvar mass is found in an elderly women, the physician should consider the possibility of malignancy, especially metastasis.