In this feature, AAOS Now publishes a series of images, challenging readers to diagnose the condition depicted. Next month, we’ll publish the responses we receive.

The images for this month’s challenge were submitted by Stephen A. Albanese, MD, and E. Mark Levinsohn, MD. They provide the following patient information:

“The patient is a 67-year-old, healthy male who complained of swelling of the middle finger. Upon examination, no inflammation or tenderness was found. Radiographs (anteroposterior and lateral views) of the hand were taken and are shown here.”

What’s your diagnosis? E-mail your decision and rationale to aaoscomm@aaos.org