DEFINITION Merkel cell carcinoma is a rare type of skin cancer that usually appears as a flesh-colored or bluish-red nodule, often on your face, head or neck. Merkel cell carcinoma is also called neuroendocrine carcinoma of the skin. Merkel cell…
DEFINITION Meralgia paresthetica is a condition characterized by tingling, numbness and burning pain in your outer thigh. The cause of meralgia paresthetica is compression of the nerve that supplies sensation to the skin surface of your thigh. Tight clothing, obesity…
DEFINITION Amyloidosis (am-uh-loi-DO-sis) is a rare disease that occurs when a substance called amyloid builds up in your organs. Amyloid is an abnormal protein that is usually produced in your bone marrow and can be deposited in any tissue or…
DEFINITION Anal itching is a common condition. The itch, situated in your anus or on the skin just around your anus, is often intense and may be accompanied by a strong urge to scratch. You may find anal itching to…
DEFINITION Anaphylaxis is a severe, potentially life-threatening allergic reaction. It can occur within seconds or minutes of exposure to something you’re allergic to, such as a peanut or the venom from a bee sting. The flood of…
DEFINITION Anal cancer is an uncommon type of cancer that occurs in the anal canal. The anal canal is a short tube at the end of your rectum through which stool leaves your body. Anal cancer can…
DEFINITION An aneurysm is an abnormal bulge or ballooning in your blood vessels. You may have one of several types of aneurysms, including: Aortic aneurysm. An aortic aneurysm forms in your aorta, a major blood…
DEFINITION Angelman syndrome is a genetic disorder that causes developmental disabilities and neurological problems, such as difficulty speaking, balancing and walking, and, in some cases, seizures. Frequent smiles and outbursts of laughter are common for people with Angelman syndrome, and…
DEFINITION Anhidrosis is the inability to sweat normally. When you don’t sweat (perspire), your body can’t cool itself, which can lead to overheating and sometimes to heatstroke — a potentially fatal condition. Anhidrosis — sometimes called hypohidrosis…
DEFINITION Malaria is a disease caused by a parasite, transmitted by the bite of infected mosquitoes. Malaria produces recurrent attacks of chills and fever. Malaria kills an estimated 1 million people each year worldwide. While the disease is uncommon in…
DEFINITION Male breast cancer is a rare cancer. Though breast cancer is most commonly thought of as a woman’s disease, male breast cancer does occur. Male breast cancer is most common in older men, though it can occur at any…
DEFINITION Approximately 15 percent of couples are infertile. This means they aren’t able to conceive a child even though they’ve had frequent, unprotected sexual intercourse for a year or longer. In about half of these couples, male infertility plays a…