Lobular carcinoma in situ (LCIS) is a rare condition that happens when you have abnormal cells in your lobules — the glands in your breasts that produce breast milk. LCIS isn’t breast cancer even though its name includes the term “carcinoma” (cancer). The abnormal cells in your breast glands aren’t cancerous. They’re “in situ,” meaning they don’t become invasive cancer that’s spreading from your lobules to …

Lactose intolerance is a reaction in your digestive system to lactose, the sugar in milk. It causes uncomfortable symptoms after you eat dairy products. Many people have difficulty digesting lactose, but not everyone experiences noticeable symptoms from it. If you do, it’s called lactose intolerance. What is lactose malabsorption? Lactose malabsorption is the inability to break down and absorb lactose molecules in …

Noncardiac chest pain is defined as recurring pain in your chest — typically, behind your breast bone and near your heart — that’s not related to your heart. In most people, noncardiac chest pain is actually related to a problem with their esophagus, most often gastroesophageal reflux disease (GERD). Stress, anxiety and depression can also manifest as chronic chest pain. Other conditions can cause …

Klippel-Trenaunay syndrome (KTS) is a rare congenital (present at birth) disorder. It changes the way your soft tissues, bones and blood vessels develop and causes a red “port-wine stain” birthmark on one limb. Many people with KTS also have abnormalities in their lymphatic system. This system helps maintain fluid balance in your body. Although Klippel-Trenaunay syndrome doesn’t have a cure, many treatments can help you manage …

Klinefelter syndrome is a genetic disorder in which people assigned male at birth (AMAB) have an additional X chromosome in their genetic code. Most people AMAB have 46 chromosomes (packages of DNA). This includes one copy of an X chromosome and one copy of a Y chromosome (46, XY). People with Klinefelter syndrome have a total of 47 chromosomes (47, XXY). Klinefelter syndrome is …

Mononucleosis, or infectious mononucleosis (“mono”), is a very contagious viral infection that most commonly affects teenagers and young adults, but it can affect children, as well. Viruses — most often Epstein-Barr virus (EBV) — and certain infections cause the illness. Mono is sometimes called “the kissing disease” because it spreads easily through bodily fluids like saliva. For most people, mono isn’t serious, and it …

Kidney stones are solid masses or crystals that form from substances (like minerals, acids and salts) in your kidneys. They can be as small as a grain of sand or — rarely — larger than a golf ball. Kidney stones are also called renal calculi or nephrolithiasis. Depending on the size of your kidney stone (or stones), you may not even …

A kidney infection (pyelonephritis) is a type of urinary tract infection (UTI). Bacteria cause it when they move from another part of your body, like your bladder, up to one or both of your kidneys. Kidney infections can be more serious than lower UTIs. See a healthcare provider if you have symptoms of a kidney infection. How common are kidney infections? About …

A seborrheic keratosis (seb-o-REE-ik ker-uh-TOE-sis) is a common benign skin growth, similar to a mole. Most people will have at least one in their lifetime. They tend to appear in mid-adulthood and their frequency increases with age. They are harmless and don’t require treatment, but you can have them removed if they bother you. Skin growths like seborrheic keratoses are …

Keratosis pilaris is a benign (not harmful) skin condition that looks like small bumps. If you have this condition, you may notice small, painless bumps on your skin around hair follicles. The bumps consist of excess keratin, which is a protein that helps form your hair, nails and skin’s outer layer (epidermis). Keratosis pilaris bumps may look red, brown or …