Congenital Methemoglobinemia-Induced Cyanosis in Assault Victim

Methemoglobinemia is a blood disorder in which there is an elevated level of methemoglobin. In contrast to normal hemoglobin, methemoglobin does not bind to oxygen, which leads to functional anemia. The signs of methemoglobinemia often overlap with other cardiovascular and pulmonary diseases, with cyanosis being the key sign of methemoglobinemia. Emergency physicians may find it challenging to diagnose cyanosis as a result of methemoglobinemia. Our patient is a healthy 28-year-old male, a heavy smoker, who presented to the emergency department with multiple minimum bruises on his body, claiming he was assaulted at work. He appeared cyanotic with an O(2) saturation of 82% (normal range is 95-100%) in room air. He also mentioned that his sister complained of a similar presentation of cyanosis but was asymptomatic. All these crucial points strengthened the idea that methemoglobinemia was congenital in this patient. The case was challenging to the emergency physician, and there was significant controversy over whether the patient's hypoxia was a result of the trauma or congenital methemoglobinemia.