Clinical Presentations of Cyanosis Associated With Acquired Methemoglobinemia In Infants: A Clinical Challenge

Lin Wang¹Yang Ye¹Delian Li¹Peng Yang¹Kexing Li¹Huanrui Hu²Yongmei Zhao^1*Xiaoliang Liu^3,4*

• ¹Longquanyi District of Chengdu Maternity and Child Health Care Hospital, Chengdu, Sichuan Province, China
• ²Department of General Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan Province, China
• ³Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, Sichuan Province, China
• ⁴Department of Pediatrics, West China Second University Hospital, West China Second University Hospital-Tianfu·Sichuan Provincial Children's Hospital, Meishan, China

Background: In infants and children, cyanosis is a common clinical finding. Particularly, central cyanosis can be associated with significant and potentially lifethreatening diseases. Acquired methemoglobinemia was a rare but severe or even fatal cause of cyanosis in infants. Given the rarity of this disorder, its timely diagnosis and appropriate management, particularly in infants, may be challenging in a clinical setting. Case report: We reported a previously healthy 49-day-old female who presented with central cyanosis. Four hours prior, this infant's guardian inappropriately prepared the infant's milk formula with spinach juice. This critical clue hinted to us that this infant might suffer from acquired methemoglobinemia. Moreover, we found her blood presented with a chocolate-brown color when her blood was drawn for a laboratory test. Furthermore, laboratory tests showed abnormal findings from arterial blood gas analysis, indicating that the significantly elevated percentage of methemoglobinemia was 44.7%. Regarding the history of inappropriately preparing the infant formula using vegetable juice and the abnormal finding of methemoglobinemia, the diagnosis of acquired methemoglobinemia was proposed; other causes of methemoglobinemia were further excluded. The treatment of methylene blue and Vitamin C was immediately initiated. Encouragingly, the cyanosis of this infant resolved one hour later, with normal results of the repeated blood gas analysis. This infant was discharged home two days later and had no abnormal findings during the follow-up.In this study, we reported a rare case of acquired methemoglobinemia in a 49-day-old infant. Inappropriately preparing the infant milk formula with spinach juice was the potential cause of methemoglobinemia in this case, which presented with central cyanosis. Our findings also suggested that pediatricians should be aware of acquired methemoglobinemia as a potential cause of cyanosis in infants.