The World Health Organisation's revised guideline value for arsenic in drinking water is 10 μg/L. Chronic arsenicosis from groundwater contamination in West Bengal produces which dermatological manifestation considered pathognomonic for advanced exposure?
- A Diffuse hyperpigmentation with raindrop depigmentation and palmoplantar keratosis ✓
- B Leukonychia (white nails)
- C Pellagra-like photosensitive dermatitis
- D Acrocyanosis with peripheral gangrene
Explanation
Chronic arsenicosis classically produces a triad of diffuse hyperpigmentation (melanosis), raindrop-pattern focal depigmentation (leucomelanosis), and palmoplantar keratosis (arsenical keratosis). These dermatological changes occur after years of exposure at >50–100 μg/L. The raindrop pattern on the trunk (alternating hyper- and hypo-pigmented spots) is pathognomonic. Peripheral gangrene ('blackfoot disease') is a Taiwanese presentation associated with very high exposure. Acrocyanosis is not characteristic. Leukonychia (Mees' lines) occurs with acute arsenic poisoning.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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