Palmoplantar keratoses and Bowen's disease in a Vietnam veteran: Could Agent Blue be implicated?

Agent Blue was an arsenical herbicide used extensively in the Vietnam War. Arsenic is one of the known causes of acquired palmoplantar keratoderma (PPK). The most common manifestation of arsenic exposure in susceptible individuals is bilateral palmoplantar hyperkeratosis. We report a 67-year-old man with no known prior exposure to arsenic in the USA or family history of PPK who developed multiple squamous cell carcinoma in situ (SCCIS) and palmoplantar hyperkeratotic lesions beginning 23 years after service in Vietnam. The SCCIS were located on the trunk and extremities in both sun-exposed and non-sun-exposed sites and his palmoplantar lesions were diagnosed concurrently with his SCCIS. He has continued to develop SCCIS since his first visit to our clinic 25 years ago.