Chronic Arsenic Poisoning
A 34-year-old woman presented to the general medicine clinic with a 3-year history of changes in skin color. Examination was notable for innumerable hypopigmented macules on a background of hyperpigmentation, creating a raindrop-like appearance on the chest (Panel A) and back. The palms (Panel B) and soles had similar changes in pigmentation, as well as hyperkeratotic papules. On additional history taking, the patient reported that neighbors who drank water from the same tube well that she used had similar skin changes. Laboratory testing revealed markedly elevated levels of arsenic in the patient’s fingernails and hair, as well as in her well water. A diagnosis of chronic arsenic poisoning was made. Chronic arsenic poisoning typically manifests as skin pigmentation changes, skin thickening, or a sensorimotor neuropathy. It is a major public health issue in West Bengal, India — where this patient lived — and Bangladesh owing to the contamination of well water. The patient was advised to find an alternative water source, and the contaminated well was sealed. At a 3-month follow-up visit, her skin changes had abated. She remains under surveillance for skin cancer and other cancers, given that her risk remains elevated even after exposure to carcinogenic arsenic has ceased.