LAUSR

Abstract Introduction While 4-chloro-1-nitrobenzene has oxidising properties and can lead to methaemoglobinaemia and haemolysis, such reports are rare. We herein describe two cases of 4-chloro-1-nitrobenzene poisoning after skin exposure and detail relevant clinical characteristics and treatment outcomes. Case presentation A 45-year-old man and his 32-year-old male co-worker presented at our department shortly after skin exposure to 4-chloro-1-nitrobenzene. They developed similar symptoms, including dizziness, dyspnoea, excessive fatigue, and coma. Patients’ chest inspection yielded normal findings. Despite maximal oxygen supplementation, neither patient exhibited improvements in the following clinical parameters: diffuse cyanosis, chocolate-coloured blood, and decreased pulse oximetry. For patients 1 and 2, methaemoglobin levels at admission were 78.6% and 63.6%, and 4-chloro-1-nitrobenzene concentrations were 4.12 μg/mL and 2.89 μg/mL, respectively. Their symptoms and methaemoglobin levels improved after we cautiously administered methylene blue; we subsequently detected oxidative haemolysis (confirmed by peripheral blood smears) that later resolved without further aggravation. No further episodes of anaemia were documented via telephone follow-up for eight months after hospital discharge for either patient. Discussion Typical features of methaemoglobinaemia included diffuse cyanosis, dark chocolate-coloured blood, elevated partial pressure of oxygen, and decreased pulse oximetry saturation. Haemolysis likely occurred secondary to the toxic effects of 4-chloro-1-nitrobenzene.