A young woman presenting with a red, painful, swollen DIP joint is most likely experiencing which condition?

The presentation of a red, painful, and swollen distal interphalangeal (DIP) joint in a young woman is characteristic of gonococcal arthritis. This type of arthritis is caused by an infection with Neisseria gonorrhoeae, often seen in sexually active individuals. The key features that support this diagnosis include the acute nature of the joint swelling, the inflammatory signs indicated by redness and pain, and the demographic context of a young woman who may be at risk for sexually transmitted infections.

This condition often presents with significant joint involvement that can evolve rapidly, typically affecting one or several joints, including the hands and feet. The presentation in young individuals and the typical involvement of the DIP joints align well with this condition. Gonococcal arthritis can also be accompanied by systemic symptoms, further distinguishing it from some of the other forms of arthritis that could involve the DIP joint but do not present as acutely or with the same inflammatory profile in a young demographic.