Cordelia is a two-month-old infant who is brought in for review by her mother, with 24 hours of persistent irritability.

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<p>Cordelia is a two-month-old infant who is brought in for review by her mother, with 24 hours of persistent irritability.</p><p>There is no clear trigger for this, Cordelia has no fever, no features of URTI, vomiting, diarrhoea or rash and is feeding well, though does not settle as usual after a feed.</p><p>There is no past or family history of note, and growth and development are normal.</p><p>This morning, her mother noticed new swelling and constriction of Cordelia’s left ring finger (pictured), which previously looked like all her other digits.</p><p>On examination, vital signs are within normal limits.</p><p>There is marked oedema, redness and congestion distal to the metacarpophalangeal joint.</p>

Dr Kate Kelso is a GP and medical editor at Australian Doctor.