“Pencil-in-cup” describes what the affected bone looks like in an X-ray: The end of the bone has eroded into a sharpened pencil shape, and this “pencil” has worn away the surface of an adjoining bone ...

Pencil-in-cup sign is sometimes called pencil-in-cup change or deformity. It’s an abnormal change in one of the small hinge-like joints of your fingers or toes. It happens when new bone begins to grow ...

Over time, arthritis mutilans leads to the destruction of the affected bones in your hands, particularly in your fingers. It can also affect your feet. People with arthritis mutilans may eventually ...