RESUMO
Arsenic keratosis can be a precursor of both Bowen's disease and squamous cell carcinoma. In fact, there is a direct dose-response relationship between the amount of arsenic exposure and the development of skin cancer. Therefore, meticulous dermatologic surveillance and follow-up are advised to detect malignancy at an early and curable stage. We herein report on a case of a 62-year-old man who presented with multiple Bowen's disease and arsenic keratosis. His past history revealed chronic exposure to arsenic through consumption of Chinese traditional herbal medicine. After a follow-up loss of 2 years, he returned with multiple extracutaneous metastases of squamous cell carcinoma, including the liver. Our case emphasizes the importance of regular follow-up and survey for skin cancer and other internal malignancies in patients with history of chronic arsenic exposure.