Shari is a 41-year-old public servant, with a background of poorly controlled Crohn’s disease, who presents with a painful enlarging skin lesion on her right lower leg for about six weeks.

Test your clinical know-how by taking the quiz below. If you select the wrong answer, have another go — you can try as many times as you like!

<p>Shari is a 41-year-old public servant, with a background of poorly controlled Crohn’s disease, who presents with a painful enlarging skin lesion on her right lower leg for about six weeks.</p><p>The lesion developed from the site of a small shaving scratch, growing rapidly within a week of the injury.</p><p>She had some cefalexin at home, which she took for a week, with no effect.</p><p>She has had no associated fever. Shari has no known allergies and has been taking sulfasalazine for years for inflammatory bowel disease.</p><p>Examination findings are normal apart from the lesion (pictured).</p><p>Blood tests — including FBC, EUC and LFT — reveal an elevated CRP of 15mg/L (normal: &lt;5). Bacterial and viral swabs are negative.</p><p>A biopsy from the ulcerative edge demonstrates neutrophilic infiltrates.</p>

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