Rain drop pigmentation is seen in
chronic arsenic exposure from occupations for polonged periods 1-20 years may develop diffuse pigmentation predominant over trunk and is superimposed by 2-10mm macules of depigmentation producing characteristic rain drop appearence. IADVL textbook of dermatology, disorders of pigmentation page 786
Chronic lead poisoning
Chronic Arsenic poisoning
Chronic Mercury poisoning
All of the above
Skin lesions and disorders of pigmentation