A 14-year-old boy of Asian origin presented with a history of bluish discolouration of the finger and toenail bed with associated mild fatiguability on exertion since early childhood. Clinical examination revealed bilaterally symmetric uniform central cyanosis with no associated clubbing. Cardiovascular and respiratory system examination was normal. Pulse oximetry revealed an oxygen saturation of 87% in all four limbs. Transthoracic and transoesophageal echocardiography showed no evidence of shunt lesions. In view of the past diagnosis of pulmonary arteriovenous fistulae made at 4 years of age, a repeat cardiac catheterisation study was done, which revealed no shunt at any level. Interestingly, arterial oxygen tension of the chocolate-brown blood was normal in all the samples, suggesting the possibility of methaemoglobinaemia. Co-oximetry revealed methaemoglobin levels of 36%, confirming the diagnosis. Secondary causes were ruled out. The family was counselled about the hereditary nature of the condition.
- haematology (incl blood transfusion)
- malignant and benign haematology
- congenital disorders
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Contributors AP was involved in the preparation and review of the manuscript. STC was involved in the review of the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Obtained.
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