Girl presented complaining of swelling, pain, redness of skin on lateral aspect of ankle for 1 day. She had local trauma 1 week back for which immobilization was done. Due to increasing pain, plaster was removed and patient was referred for ultrasound of local swelling. 

Ultrasound shows collection with echoes involving subcutaneous plane - an abscess - abutting fibular cortex. There is secondary involvement of fibula from adjacent soft tissue infection.

Incision and drainage revealed pus.