P-chloroaniline poisoning causing methemoglobinemia: a case report and review of the literature.

Background. Methemoglobin (MetHb) most commonly results from exposure to an oxidizing chemical but may also arise from genetic, dietary, or even idiopathic etiologies. P-chloroaniline (PCA) was one of the first substances described in the context of acquired methemoglobinemia. Case Report. We report the case of a cyanotic chemistry worker who presented to our emergency department (ED) after working with PCA. His peripheral oxygen saturation (SpO2) measured by pulse oximetry was at 81% and remained on that level despite oxygen administration (100% oxygenation via nonrebreather mask). His MetHb level was measured at 42.8% in arterial blood gas analysis. After treatment with intravenous methylene blue cyanosis resolved and the patient was discharged after 36 hours of observation. Conclusion. Acquired methemoglobinemia is a treatable condition, which may cause significant morbidity and mortality. The knowledge about the most common causes, fast diagnostic, and proper treatment is crucial.