A 17-year-old boy presented to the rheumatology unit with a one-year history of bilateral symmetrical proximal muscle weakness and erythematous papules over the left third metacarpophalangeal and right third proximal interphalangeal joints with subsequent ulceration. He also reported purulent discharge with severe pain and restriction of movement of the right digit (Panel A). The discharge resolved spontaneously before his presentation to our clinic. The history of severe pain and discharge prompted further evaluation with a radiographand MRI of the right hand.

1. What is the clinical sign shown in image A?

2. What is the likely diagnosis?

3. What is the complication shown?