Cyst on the Leg

An abnormal membranous sac that can develop on the skin or internal organs, a cyst can be small or large. It could affect people of all age groups. Cysts that appear under the skin are broadly classified into sebaceous cysts or epidermoid cysts.

The former refers to a closed sac that is filled with sebum, which is the oily secretion of the sebaceous glands that keeps the skin moisturized. The latter refers to a closed sac that is filled with a scleroprotein called keratin. More often than not, sebaceous cysts develop around inflamed hair follicles.

Trauma to the skin could also be a contributing factor. These closed sacs appear like a lump under the skin. Usually, these cysts are painless. However, the affected area might become red, swollen, and tender to touch, if the cyst becomes inflamed. Medical assistance must be sought under such circumstances.

The following sections provide information on the causes of unicameral bone cyst on thigh bone and baker's cyst behind the knee joint.

Baker's Cyst
Also called popliteal cyst, a Baker's cyst is caused by the buildup of excess synovial fluid in the area at the back of the knee. It could develop due to the following reasons:

➻ Inflammation of the knee joint due to osteoarthritis
➻ Rheumatoid arthritis
➻ Tear in the meniscal cartilage of the knee

In some cases, the cyst might not cause any pain. At times, the affected individual might experience the following symptoms:

➻ Knee pain
➻ Stiffness
➻ Swelling behind the knee

In rare cases, the cyst might rupture, thereby giving rise to symptoms that are similar to the ones experienced due to deep vein thrombosis.

Unicameral Bone Cyst
This condition is more common in children and adolescents. Basically, these are cavities within the bone that get filled with fluid. These mostly affect the humerus (upper arm bone) or the femur (thigh bone). The cysts mostly form at the end of the bone, around the joint and the growth plate.

More often than not, when the child is fully grown, the area fills in with bone. While the cysts are mostly asymptomatic, in rare cases, the cysts might expand, thereby weakening the bone and putting one at a risk of developing a fracture.

While skin cysts can be easily diagnosed by conducting a physical examination, imaging tests need to be conducted in other cases. For instance, an MRI scan and ultrasound can help in diagnosing a Baker's cyst, whereas an X-ray examination, magnetic resonance imaging (MRI) scan, and computed tomography (CT) scan might be conducted for diagnosing a unicameral bone cyst on the leg.

Treatment is needed in case of cysts that are symptomatic. Some common treatment options are listed below:

➻ In case of a sebaceous cyst, applying warm compresses over the affected area would prove beneficial.
➻ In case of small cysts, administration of steroids into the cyst would help alleviate swelling.
➻ For large cysts that are painful, surgical removal might be considered.

➻ Analgesics and non-steroidal anti-inflammatory drugs might be recommended for alleviating the pain and swelling.
➻ The treatment of Baker's cysts involves needle aspiration for the drainage of fluid, and administration of cortisone injections for reducing the swelling. Physical therapy, ice therapy, or application of warm compresses might also help.

➻ Needle aspiration for the drainage of fluid, and administration of cortisone injections might be recommended for unicameral bone cysts as well. In severe cases, after removing the fluid, the cyst is scraped out of the bone. Thereafter, the hole is filled with a bone graft (which might be taken from a donor, or from another bone from the body). A bone cement mixture might also be used for filling the hole. After the surgery, the patient should take rest, and refrain from performing strenuous physical activities.

On a concluding note, sebaceous cysts on the leg can be easily treated. Individuals affected by inflammatory joint conditions are at a risk of developing Baker's cyst, which is why they must consult a doctor, if they experience the aforementioned symptoms.

Disclaimer: The information provided in this story is solely for educating the reader. It is not intended to be a substitute for the advice of a medical expert.