a bone cyst.
sol·i·tar·y bone cyst
a unilocular cyst containing serous fluid and lined with a thin layer of connective tissue, occurring usually in the shaft of a long bone in a child.
osteocystoma/os·teo·cys·to·ma/ (-sis-to´mah) a bone cyst.
a cystic tumor in a bone.
osteocystoma(1) A nonspecific term for a cyst within a bone.
(2) Unicameral bone cyst, see there.