12th January 2024

A 36-year-old male presents to A&E with a one-week history of dry cough, malaise, diarrhoea and skin rash.

A 36-year-old male presents to A&E with a one-week history of dry cough, malaise, diarrhoea and skin rash. On examination, he has signs of conjunctival pallor, and on his skin, he has multiple lesions with a central darker area surrounded by a lighter circle and then a peripheral erythematous margin. There are no mucosal lesions seen. He has blood tests sent, which show the following: 

Hb 82 g/L (130-180)

WCC 14.0 x 10*9/L (4.0-11.0)

Bilirubin 41 µmol/L (<21)

ALT 14 U/L (<41)

Urea: 6.1 mmol/L (2.5 – 7.8 mmol/L)

CRP 107 mg/L (<10)

Which test is most likely to confirm the diagnosis in this patient?

Select the SINGLE most appropriate option from the list below. Select ONE option only.