We report a woman with acute arsenic poisoning, who developed an erythroderma with vesicles and pustules after the ingestion of 8-16 g of sodium arsenite. Simultaneously, she presented a herpes simplex virus infection. Skin biopsies showed unique features which included multiple small pigment granules inside and outside the histiocytes. In our opinion, these findings are consistent with acute arsenic poisoning, and constitute the first histological description of this entity in skin.