Visual Hallucinations With Arsenic Trioxide Therapy in Acute Promyelocytic Leukemia

A 68-year-old male with a history of diabetes and hypertension was diagnosed with acute promyelocytic leukemia (APML). He underwent induction therapy with all-trans retinoic acid (ATRA) and arsenic trioxide. He had a complete hematologic response and was initiated on consolidation therapy with arsenic trioxide (0.15 mg/kg/day intravenous (IV)) and ATRA (45 mg/per meter square of body surface area/day IV). He developed blurred vision and floaters after a few days. Soon after, he felt that his diabetic neuropathy had suddenly worsened. The floaters and flashing lights worsened and morphed into visual hallucinations. He reported seeing figures watching him from the corner of the room. He was admitted and head imaging was unremarkable. Routine labs did not show anything unusual. Arsenic trioxide therapy was held. The hallucinations gradually started decreasing and eventually subsided after around eight weeks. ATRA was continued but arsenic was permanently discontinued. Arsenic is known to cause poisoning if exposed in significant amounts. The arsenic dose used for APML is substantially low (0.15 mg/kg/day IV). We delineate this unanticipated case of arsenic toxicity leading to severe neurological symptoms like visual hallucinations which has not been previously reported in the literature. It is imperative to closely monitor patients who are on arsenic therapy and inform them about possible rare toxicities.