Dermal discoloration due to osmium tetroxide

Introduction: Osmium tetroxide is a strong oxidizing agent. After dermal exposure to osmium tetroxide, skin discoloration and red papules can occur. We describe a patient with skin discoloration due to osmium tetroxide.Case summary: A 25-year-old postgraduate student unintentionally exposed his hand to osmium tetroxide while working in a laboratory setting. After immediate washing, he sought medical care due to left middle finger discoloration. He reported no discomfort in the affected area. Thorough water rinsing was continued, and corticosteroid ointment was applied.Images: Our patient developed dark brown pigmentation on the ventral side of the left middle finger. The pigmentation disappeared one week later.Conclusion: Osmium tetroxide may induce dark brown skin discoloration.