Leg Pain

Cysts and Tumors

This is the final article in Pain.com’s series about the various causes of leg pain. This article discusses bone cysts and bone tumors, two of the possible causes of leg pain.

A cyst, in general, is an abnormal but non-cancerous fluid-filled structure that appears somewhere in the body. Bone cysts are relatively uncommon compared to other types of cysts, such as ovarian cysts, but they can occur. There are two classifications of bone cysts. A unicameral bone cyst is a cyst that appears in a single bone. These cysts, also called “simple” cysts to distinguish them from the other type of bone cyst, are most common in the arm and thigh bones, close to the shoulder and hip joints. They can also occur in the heel bone, ankle bones or pelvis, but this is a less common occurrence. Unicameral bone cysts are more common in children and teenagers than in adults.

This type of bone cyst may go completely unnoticed until a patient gets an X-ray for another reason; however, in some cases the patient may experience some pain when weight is placed on the cyst. Unicameral bone cysts are diagnosed with simple x-rays, but other types of medical imaging may be used as well. It is not known why unicameral bone cysts form, and it is not known how they can be prevented. Much of the time, these bone cysts do not require any treatment except to get x-rays to see if the cyst is getting bigger. Surgery may be needed to stabilize the bone if the simple bone cyst is located so that the bone is at high risk for fracture. Surgery to repair simple bone cysts includes draining or aspirating the fluid from the cyst and injecting the empty cyst with either a steroid medication or a bone graft. The bone will eventually grow back and fill the hole left by the drained cyst.

An aneurysmal bone cyst is a type of bone cyst that affects mostly older children and teenagers. It is still a non-cancerous growth, but in general it is more severe than a simple bone cyst because it can expand to other parts of the bone. An aneurysmal bone cyst takes the form of smaller bone cysts that are connected. Aneurysmal bone cysts are more likely than simple bone cysts to cause pain and put the patient at risk for bone fractures. These bone cysts also cause swelling and bone deformities. It is not known what causes these bone cysts or how to prevent them. Treatment for aneurysmal bone cysts usually involves surgery to remove the cysts and a bone graft. Some cases of aneurysmal bone cysts are completely cured after one surgery, and other times the cysts return.

A tumor is a solid mass, as opposed to a fluid-filled cyst. Bone tumors can be benign or malignant (cancerous). Both types of tumors usually cause some degree of pain. The pain is not usually sharp or intense, but more of a dull, aching sensation. The treatments for benign and malignant tumors are different, because cancerous tumors may spread to other parts of the body. If a bone tumor is located during an X-ray, MRI or other type of medical imaging procedure, a doctor will take a biopsy of the tumor to determine if the tumor is cancerous or benign.

Examples of benign bone tumors include fibrous dysplasia, giant cell tumors, enchondroma and osteochondroma. Benign bone tumors can either be left alone and monitored or surgically removed without much difficulty. It is not known why benign bone tumors form or how to prevent them. In rare cases, benign bone tumors may eventually become malignant. Sometimes, benign tumors will regrow after surgery and require further treatment.

Examples of common malignant bone tumors include multiple myeloma, osteosarcoma, Ewing’s sarcoma and chondrosarcoma. Multiple myeloma affects the bone marrow and is most common in people who are between the ages of 50 and 70. Osteosarcoma is more common in younger people and it usually affects the knee, shoulder or hip joints. Ewing’s sarcoma affects younger people and is most common in the arm, leg, rib cage and pelvis. Chondrosarcoma frequently affects people in middle age and is common in the shoulder and hip.

Malignant bone tumors require more intensive treatment than benign bone tumors. If the cancer is caught in the early stages, surgery alone may cure the patient. A patient may be fitted with a prosthetic bone in some cases, and in other cases, amputation of a limb may be necessary to ensure that all of the cancerous cells are eradicated. In more advanced cases of bone cancer, a patient may require chemotherapy or radiation treatment. The prognosis for bone cancer varies depending on which type of bone cancer the patient has and how far advanced it is.

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