<unk> s result from an abnormal formation of normal tissue, although the underlying reasons for the abnormality are not fully understood. They grow along with, and at the same rate as, the organ from whose tissue they are made, and, unlike cancerous tumors, only rarely invade or compress surrounding structures significantly.
Hamartoma
Thecoma
Askin's tumor
Lipoblastoma
Cylindroma
Syringoma
Neural fibrolipoma
Luteoma