Revised Draft – June , 2000 Chapter 4 : Diagnosis and treatment of chronic arsenic poisoning

Humans are exposed to arsenic (As) primarily from air, food and water. However, elevated inorganic As in drinking water is the major cause of As toxicity. Most of the reports of chronic As toxicity in man focus attention on skin manifestations because of its diagnostic specificity, but As often affects most systems of the body. The clinical manifestations of chronic As intoxication are dependent on host susceptibility, the dose and the time course of exposure. The symptoms are often insidious in onset and varied in nature. However in a few epidemiological studies no significant clinical features of toxicity were attributed to chronic intake of As contaminated water. Although chronic As toxicity produces varied non malignant manifestations as well as cancer of skin and different internal organs, dermal manifestations such as hyperpigmentation and hyperkeratosis are diagnostic of chronic arsenicosis. The pigmentation of chronic As poisoning commonly appears in a finely freckled, " raindrop " pattern of pigmentation or depigmentation that is particularly pronounced on the trunk and extremities and has a bilateral symmetrical distribution (Fig. 4.1.1-Mild pigmentation (a) Diffuse melanosis (with mild keratosis), (b) Mild spotty pigmentations, (c) Mild spotty depigmentations. (Guha Mazumder DN & Ghosh AK, personal collection) and Fig. 4.1.2-(a) Moderate pigmentation, (b) Severe pigmentation. (Guha Mazumder DN & Ghosh AK, personal collection) (PENDING)) Pigmentation may sometimes be blotchy and involve mucous membranes such as the undersurface of the tongue or buccal raindrop appearance results from the presence of numerous rounded hyperpigmented or hypopigmented macules (typically 2-4 mm in diameter) widely dispersed against a tan-to-brown hyperpigmented background (Tay 1974). Although less common, other patterns include diffuse in which the hypopigmented macules take a spotty, white appearance usually occur in the early stages of intoxication. Arsenical hyperkeratosis appears predominantly on the palms and the plantar aspect of the feet, although involvement of the dorsum of the extremities and the trunk have also been described. In 3 the early stages, the involved skin might have an indurated, gritlike character that can be best appreciated by palpation; however, the lesions usually advance to form raised, punctated, 2-4 mm wartlike keratosis that are readily visible (Tay 1974). Occasional lesions might be larger (0.5 to 1 cm) and have a nodular or horny appearance occurring in the palm or dorsum of the feet. In severe cases, the hands and soles present with diffuse verrucous lesions (Fig. 4.1.3 (a) Mild keratosis, (b) moderate keratosis (i) …