Solitary bone cyst is essentially a disease of the growing period and rarely begins after adult life is reached. It has become extensively recognized and investigated only since the introduction of the roentgen ray. Four main theories have been advanced to explain it. These are: first, that it is a degenerated tumor; second, that it is a localized malacia or dystrophy analogous to von Recklinghausen's multiple fibrocystic disease, occurring mainly in adults; third, that it is the result of hematoma in the bone marrow and, fourth, that it is an infection.
The tumor theory has been abandoned. The theory that it is a localized malacia, advanced by M. B. Schmidt, 1 was based on the supposition that there was extensive replacement of normal marrow and bone by fibrous marrow before cyst formation, which has not been found to be the case. There are no generalized changes in the skeleton of
PHEMISTER DB, GORDON JE. THE ETIOLOGY OF SOLITARY BONE CYST. JAMA. 1926;87(18):1429-1433. doi:10.1001/jama.1926.02680180001001