Can you work out the cause of this fluctuant mass?

Felicity, a 25-year-old teacher, presents complaining of a tender swelling over her frontal bone with associated fever for the past two days.

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!

Dr Paul Muthiah is GP on the Central Coast, NSW, and medical co-editor at Australian Doctor.

CMAJ 2019; 11 Feb.