What Is a Subchondral Bone Cyst? It's a fluid-filled sac that forms in one or both of the bones that make up a joint. They're especially common at the knee or hip. The cysts show up just under the ...

Mastoiditis is a serious infection of the mastoid, the hard, prominent bone just behind and under the ear. It is rare and can be life threatening without treatment. Symptoms of mastoiditis include ...

Mastoiditis is a serious bacterial infection that affects the mastoid bone behind the ear. Without prompt treatment, mastoiditis can potentially lead to meningitis. Meningitis is a potentially life ...