Palmoplantar keratoderma with mottled pigmentation: A clue to chronic arsenicosis.

Arsenical keratosis is a precancerous skin condition resulting from chronic exposure to arsenic, typically through ingestion of contaminated water, food (notably rice), certain medications, or tobacco products. Exposure can also occur via industrial and environmental sources, including some herbal remedies. According to the World Health Organization, a minimum of six months of exposure above safe limits is required to develop toxicity, with cutaneous manifestations appearing anywhere from 4 to 40 years later. Clinically, it presents as thick, painful, keratotic lesions on the palms and soles, often with accompanying pigmentary changes such as a raindrop pattern. Chronic arsenic toxicity may also cause systemic symptoms involving the nervous, hepatic, pulmonary, and gastrointestinal systems.