A bone cyst or geode is a

cyst A cyst is a closed sac, having a distinct envelope and division compared with the nearby tissue. Hence, it is a cluster of cells that have grouped together to form a sac (like the manner in which water molecules group together to form a bubble ...

that forms in

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...

. Types include: * Unicameral bone cyst * Aneurysmal bone cyst * Traumatic bone cyst

Diagnosis

CT scan A computed tomography scan (CT scan; formerly called computed axial tomography scan or CAT scan) is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers ...

s, bone cysts that have a radiodensity of 20 Hounsfield units (HU) or less, and are

osteolytic Osteolysis is an active resorption of bone matrix by osteoclasts and can be interpreted as the reverse of ossification. Although osteoclasts are active during the natural formation of healthy bone the term "osteolysis" specifically refers to a pat ...

, tend to be aneurysmal bone cysts. In contrast, intraosseous

lipoma A lipoma is a benign tumor made of fat tissue. They are generally soft to the touch, movable, and painless. They usually occur just under the skin, but occasionally may be deeper. Most are less than in size. Common locations include upper back, ...

s have a lower radiodensity of -40 to -60 HU.

Treatment and Prevention

Simple (Unicameral) Bone Cyst

Some unicameral bone cysts may spontaneously resolve without medical intervention. Specific treatments are determined based on the size of the cyst, the strength of the bone, medical history, extent of the disease, activity level, symptoms an individual is experiencing, and tolerance for specific medications, procedures, or therapies. The types of methods used to treat this type of cyst are curettage and

bone grafting Bone grafting is a surgical procedure that replaces missing bone in order to repair bone fractures that are extremely complex, pose a significant health risk to the patient, or fail to heal properly. Some small or acute fractures can be cured wit ...

, aspiration, steroid injections, and bone marrow injections.

Watchful waiting Watchful waiting (also watch and wait or WAW) is an approach to a medical problem in which time is allowed to pass before medical intervention or therapy is used. During this time, repeated testing may be performed. Related terms include ''expe ...

and activity modifications are the most common nonsurgical treatments that will help resolve and help prevent unicameral bone cysts from occurring and reoccurring.

Aneurysmal Bone Cyst

Aneurysmal bone cysts can be treated with a variety of different methods. These methods include open curettage and bone grafting with or without adjuvant therapy, cryotherapy, sclerotherapy, ethibloc injections, radionuclide ablation, and selective arterial embolization. En-block resection and reconstruction with strut grafting are the most common treatments and procedures that prevent recurrences of this type of cyst.

Traumatic Bone Cyst

The traumatic bone cyst treatment consists of surgical exploration, curettage of the osseous socket and bony walls, subsequent filling with blood, and intralesional steroid injections. Young athletes can reduce their risk of traumatic bone cyst by wearing protective mouth wear or protective headgear.

History

Aneurysmal bone cysts are benign neoformations which can affect any bone. More than half occur in the metaphysis of long bones (especially

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...

and

tibia The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...

) and between 12 and 30% in the spine. They were described in 1893 by Van Arsdale, who called these lesions "homerus ossifying haematoma". In 1940 Ewing used the term "aneurismal" to describe these lesions. Jaffé and Lichtenstein first coined the term "aneurismal cyst" in 1942 In 1950 they modified this term to "aneurismal bone cyst". They may be associated with bone tumors. The simple bone cyst is a common, benign, fluid-containing lesion, most commonly found in the metaphysis of long bones, typically the proximal

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

or femur. Pathologic fractures are common, often with minor trauma. These cysts typically resolve after skeletal maturity and are not typically associated with bone tumors. The cause is unknown. These were first recognised as a distinct entity in 1910. Jaffe and Lichtenstein provided a detailed discussion of simple bone cysts in 1942. The traumatic bone cyst, also referred to as a simple bone cyst or hemorrhagic cyst, is a pseudocyst that most commonly affects the mandible of young individuals. It is a benign empty or fluid-containing cavity within the mandible body that does not have evidence of a true epithelial lining. This type of bone cyst is a condition found in the long bones and jaws. There is no definitive cause, though it relates to trauma in the oral region. The likelihood of males being affected by this condition is frequently greater than in females. It appears on radiographs as a unilocular radiolucent area with an irregular but well-defined outline. This term was first described by Lucas in 1929.

References

External links

{{Authority control Musculoskeletal disorders