All Diseases

An abdominal aortic aneurysm is an enlarged area in the lower part of the aorta, the major blood vessel that supplies blood to the body. The aorta, about the thickness of a garden hose, runs from your heart through the center of your chest and abdomen. Because the aorta is the body's main supplier of blood, a ruptured abdominal aortic aneurysm can cause life-threatening bleeding.

Depending on the size and rate at which your abdominal aortic aneurysm is growing, treatment may vary from watchful waiting to emergency surgery. Once an abdominal aortic aneurysm is found, doctors will closely monitor it so that surgery can be planned if it's necessary. Emergency surgery for a ruptured abdominal aortic aneurysm can be risky.

Absence seizures involve brief, sudden lapses of consciousness. They're more common in children than adults. Someone having an absence seizure may look like he or she is staring into space for a few seconds. This type of seizure usually doesn't lead to physical injury.

Absence seizures usually can be controlled with anti-seizure medications. Some children who have them also develop other seizures. Many children outgrow absence seizures in their teens.

Acanthosis nigricans (ak-an-THOE-sis NIE-grih-kuns) is a skin condition characterized by areas of dark, velvety discoloration in body folds and creases. The affected skin can become thickened and may smell bad. Most often, acanthosis nigricans affects your armpits, groin and neck.

These skin changes typically occur in people who are obese or have diabetes. Children who develop the condition are at higher risk of developing type 2 diabetes. More rarely, acanthosis nigricans can be a warning sign of a cancerous tumor in an internal organ, such as the stomach or liver.

Acanthosis nigricans is most common in Native Americans, blacks and Hispanics. There's no specific treatment for acanthosis nigricans. Treatment of underlying conditions may restore some of the normal color and texture to affected areas of skin.

Achilles tendinitis is an overuse injury of the Achilles (uh-KIL-eez) tendon, the band of tissue that connects calf muscles at the back of the lower leg to your heel bone.

Achilles tendinitis most commonly occurs in runners who have suddenly increased the intensity or duration of their runs. It's also common in middle-aged people who play sports, such as tennis or basketball, only on the weekends.

Most cases of Achilles tendinitis can be treated with relatively simple, at-home care under your doctor's supervision. Self-care strategies are usually necessary to prevent recurring episodes. More-serious cases of Achilles tendinitis can lead to tendon tears (ruptures) that may require surgical repair.

Achilles (uh-KILL-eez) tendon rupture is an injury that affects the back of your lower leg. It most commonly occurs in people playing recreational sports.

The Achilles tendon is a strong fibrous cord that connects the muscles in the back of your calf to your heel bone. If you overstretch your Achilles tendon, it can tear (rupture) completely or just partially.

If your Achilles tendon ruptures, you might feel a pop or snap, followed by an immediate sharp pain in the back of your ankle and lower leg that is likely to affect your ability to walk properly. Surgery is often the best option to repair an Achilles tendon rupture. For many people, however, nonsurgical treatment works just as well.

An ACL injury is the tearing of the anterior cruciate (KROO-she-ate) ligament, or ACL, inside your knee joint. An ACL injury most commonly occurs during sports that involve sudden stops and changes in direction — such as basketball, soccer, tennis and volleyball.

Immediately after an ACL injury, your knee may swell, feel unstable and become too painful to bear weight. Many people hear or feel a "pop" in their knee when an ACL injury occurs.

Depending on the severity of your ACL injury, treatment may include surgery to replace the torn ligament followed by rehabilitation exercises to help you regain strength and stability. If your favorite sport involves pivoting or jumping, a proper training program may help reduce your chances of an ACL injury.

Acne is a skin condition that occurs when your hair follicles become plugged with oil and dead skin cells. Acne usually appears on your face, neck, chest, back and shoulders. Effective treatments are available, but acne can be persistent. The pimples and bumps heal slowly, and when one begins to go away, others seem to crop up.

Acne is most common among teenagers, with a reported prevalence of 70 to 87 percent. Increasingly, younger children are getting acne as well.

Depending on its severity, acne can cause emotional distress and scar the skin. The earlier you start treatment, the lower your risk of lasting physical and emotional damage.

Acoustic neuroma is an uncommon, noncancerous (benign) and usually slow-growing tumor that develops on the main nerve leading from your inner ear to your brain. Because branches of this nerve directly influence your balance and hearing, pressure from an acoustic neuroma can cause hearing loss, ringing in your ear and unsteadiness.

Also known as vestibular schwannoma, acoustic neuroma usually grows slowly or not at all. However, in a few cases, it may grow rapidly and become large enough to press against the brain and interfere with vital functions.

Treatments for acoustic neuroma include regular monitoring, radiation and surgical removal.

Acromegaly is a hormonal disorder that develops when your pituitary gland produces too much growth hormone during adulthood. When this happens, your bones increase in size, including those of your hands, feet and face. Acromegaly usually affects middle-aged adults.

In children who are still growing, too much growth hormone can cause a condition called gigantism. These children have exaggerated bone growth and an abnormal increase in height.

Because acromegaly is uncommon and physical changes occur gradually, the condition often isn't recognized immediately; sometimes not for years. If not treated promptly, acromegaly can lead to serious illness and even become life-threatening. However, available treatments for acromegaly can reduce your risk of complications and significantly improve your symptoms, including the enlargement of your features.

An actinic keratosis (ak-TIN-ik ker-uh-TOE-sis) is a rough, scaly patch on your skin that develops from years of exposure to the sun. It's most commonly found on your face, lips, ears, back of your hands, forearms, scalp or neck.

Also known as solar keratosis, an actinic keratosis enlarges slowly and usually causes no signs or symptoms other than a patch or small spot on your skin. These lesions take years to develop, usually first appearing in older adults.

A small percentage of actinic keratosis lesions can eventually become skin cancer. You can reduce your risk of actinic keratosis by minimizing your sun exposure and protecting your skin from ultraviolet (UV) rays.