Janet is a 51-year-old clerk with a five-year history of a gradually enlarging, painful erythematous lesion on her left fifth finger.

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<p>Janet is a 51-year-old clerk with a five-year history of a gradually enlarging, painful erythematous lesion on her left fifth finger (pictured).</p><p>The lesion has enlarged from the fingertip to extend under the distal aspect of the nail plate. It is now so uncomfortable that she avoids using the digit when typing at work. The lesion is markedly more painful and sensitive with cold exposure.</p><p>She is otherwise well, with no history of trauma and no family history of note.</p><p>The lesion has previously been diagnosed as a viral wart, and she briefly tried ablative therapy with no effect.</p><p>On examination, there is a 6mm soft, exquisitely tender lesion affecting the right fifth fingertip (pictured).</p><p>There is no associated nail plate dystrophy, and the rest of the skin and joint examination is normal. A plain X-ray shows evidence of bony erosion of the distal phalanx tuft.</p>

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