bone spur

It kinda looks like a bubble.

a bursa
solitary bone cyst a pathologic bone space in the metaphyses of long bones of growing children; it may be either empty or filled with fluid and have a delicate connective tissue lining.

The Sistrunk procedure is a surgical operation used to remove a thyroglossal duct cyst. It involves excising the cyst as well as a portion of the hyoid bone and the tract that connects the cyst to the base of the tongue. This procedure helps prevent recurrence of the cyst by removing potential residual tissue.

This essentially is a cyst inside of the neck of the hip bone. The peripheral sclerotic area is the outside of this "cyst" and has a lot of calcium in it... thus it shows up as a very white area on xray, since it is more dense (because of the calcium). Hypo-dense just means there isn't much calcium in the middle of this bone "cyst" so it shows up on the xray as a dark area (hypo= less).