Past Marks: A Case Report of Basal Cell Carcinoma Induced by Arsenic Exposure.

Basal cell carcinoma (BCC) is one of the most common forms of skin cancer worldwide. Chronic exposure to arsenic, particularly in its inorganic form, has been identified as a potential etiological factor in its development. However, not all individuals exposed to arsenic will develop BCC, suggesting that genetic and environmental factors influence susceptibility. Arsenic was historically used for medicinal purposes, most notably in Fowler's solution, once prescribed for conditions such as psoriasis. Despite its past therapeutic applications, arsenic is now classified as a carcinogen due to its well-established toxicity.  The authors present a case of a 69-year-old patient with a history of prolonged use of Fowler's solution for psoriasis, who subsequently developed recurrent BCC, requiring continuous surveillance and treatment, such as surgery, cryotherapy, and laser therapy. Given the significant personal history of long-term exposure to an arsenic-based solution, arsenic was identified as the most plausible contributing factor in the development of cutaneous neoplasms in this case. This case highlights the importance of a detailed medical history, including drugs or other toxic agents that the patient may have used previously. In particular, patients with known exposure to arsenic, especially for periods exceeding six months, should undergo lifelong surveillance due to the increased risk of developing skin cancer and other arsenic-related health conditions.