A 72-year-old man was admitted to hospital because of backache. Physical examination also revealed a genital skin lesion with inguinal lymphadenopathy. Skin biopsy showed an infiltrating adenoma, arising from extramammary Paget disease. MRI of the vertebral column revealed multiple osteolytic lesions, likely metastases. The patient was diagnosed with metastatic extramammary Paget disease, which has a poor prognosis.