Macular degeneration is a common eye disease that affects central vision, making it difficult to see things directly in front of you. While it can cause significant vision loss, it does not lead to complete blindness, and treatments are available to help manage the condition.

Macular oedema is swelling in a small but vital area at the back of your eye that affects your ability to see fine details and read clearly, but with proper treatment and monitoring, many people can reduce the swelling and protect their vision.

Macular telangiectasia, or MacTel, is a disease that damages the central part of your vision, affecting your ability to read, drive, and recognize faces. While it’s a rare condition, understanding what happens in your eyes can help you manage the disease and maintain your quality of life.

Magnetic resonance imaging (MRI) is a powerful medical test that creates detailed pictures of the inside of your body without using radiation, helping doctors diagnose and monitor many different health conditions.

Major depression is more than just feeling sad. It is a serious medical condition that affects how you feel, think, and handle daily activities, and it can be effectively treated with the right support.

Malabsorption is a digestive disorder where your small intestine cannot properly absorb the nutrients, vitamins, and minerals from the food you eat into your bloodstream, potentially leading to nutritional deficiencies and various health complications.

Venous malformation is the most common type of vascular malformation, affecting approximately 1 to 2 in every 10,000 people. These abnormal clusters of veins are present at birth and grow slowly with the child, often causing pain, swelling, and visible discoloration of the skin.

A malignant central nervous system neoplasm is a cancerous tumor that develops in the brain or spinal cord. These tumors grow quickly and can spread into surrounding tissue, causing serious health problems that require immediate medical attention.

Malignant fibrous histiocytoma is a rare and aggressive type of cancer that affects soft tissues or bones, most commonly appearing as a painless mass in the arms or legs of older adults, though it can occur in children and throughout the body.

Malignant gliomas are rapidly progressive brain tumors that grow quickly and can invade healthy brain tissue, making them among the most serious types of brain cancer with very high rates of illness and death.

Malignant lymphoid neoplasm, commonly known as lymphoma, is a group of blood cancers that develop when white blood cells in the lymphatic system grow out of control and spread to other parts of the body.

Malignant mast cell neoplasms are a group of serious diseases where abnormal mast cells—immune cells that normally help fight infections and control allergic responses—grow out of control and can invade various parts of the body.

Malignant melanoma is a serious type of skin cancer that begins in cells called melanocytes, which produce the pigment that gives skin its color. While it accounts for only about 1% of all skin cancers, it causes the great majority of skin cancer-related deaths. When detected early, melanoma has a 99% cure rate, but if left untreated, it can spread quickly to other organs.

Malignant melanoma of the eyelid is a rare but aggressive form of skin cancer that can spread to other parts of the body. Though it makes up less than 1% of all eyelid cancers, early detection and proper treatment are crucial to prevent serious complications.

Stage II melanoma is a localized skin cancer that has grown deeper into the skin layers but has not yet spread to lymph nodes or other parts of the body. Understanding the characteristics of this stage and available treatment options is essential for making informed decisions about your care.

Stage III melanoma means the cancer has spread beyond the original site to nearby lymph nodes, lymph vessels, or skin, but has not reached distant organs. This stage carries a significant risk of recurrence, but modern treatments offer real hope for preventing the cancer from returning.

Stage IV melanoma is the most advanced form of this skin cancer, where the disease has spread beyond its original location to distant parts of the body such as the lungs, liver, brain, or other organs. While this diagnosis is serious, major advances in treatment over the past decade have dramatically improved outcomes for many patients.

Ampullary cancer is a rare type of cancer that develops in a small but critical part of the digestive system where bile and digestive juices meet before entering the intestine.

Choroidal melanoma is a rare but serious cancer that develops in the eye’s middle layer, representing the most common primary eye cancer in adults, though it affects only a small number of people each year.

When cancer spreads through the body but doctors cannot find where it first started, this creates a challenging medical puzzle that requires careful testing and specialized care to guide treatment decisions.

Malignant oligodendroglioma is a fast-growing brain tumor that requires prompt treatment, but advances in understanding its genetic characteristics have improved outcomes for many patients.

Malignant peritoneal neoplasm is a serious cancer affecting the peritoneum, the thin membrane lining the abdomen and covering internal organs. This rare condition can develop directly in the peritoneum or spread from cancers in nearby organs, and often goes unnoticed until it reaches advanced stages.

Cancers of the urinary tract, particularly bladder cancer, are among the most common cancers affecting people worldwide, with thousands of new cases diagnosed each year and a strong tendency to return even after successful treatment.

Mantle cell lymphoma is a rare type of blood cancer that develops when certain white blood cells grow out of control. While it cannot be cured, treatment can help manage symptoms and extend periods when the disease is not active.

Mantle cell lymphoma typically follows a pattern of remission and relapse, where the disease responds well to initial treatment but tends to return over time. Each time the cancer comes back, treatment options remain available, though responses often become shorter with each subsequent relapse.

Mantle cell lymphoma can stop responding to treatment or return after remission, presenting one of the most difficult challenges in cancer care today.

Mantle cell lymphoma stage II affects two or more groups of lymph nodes on the same side of the diaphragm. This rare blood cancer develops when abnormal B cells grow out of control in the lymphatic system, typically requiring treatment with a combination of therapies.

Mantle cell lymphoma stage III is a rare and aggressive form of blood cancer that affects lymph nodes on both sides of the diaphragm. While the diagnosis can be challenging, understanding this condition and the available treatment options can help patients and their families navigate the journey ahead.

Mantle cell lymphoma stage IV represents the most advanced form of this rare blood cancer, where the disease has spread beyond the lymph nodes to other parts of the body. Understanding this diagnosis, its implications, and available treatment options can help patients and their families navigate this challenging journey.

Marfan syndrome is a genetic condition that weakens the body’s connective tissue, affecting the heart, blood vessels, eyes, bones, and other organs. With proper care and monitoring, people with this condition can live long and productive lives.

Marginal zone lymphoma is a slow-growing type of cancer that affects the body’s immune system, typically diagnosed in people over age 60, and can often be treated successfully with various approaches depending on where the disease develops.

When marginal zone lymphoma returns after treatment or stops responding to therapy, patients face a challenging situation that requires specialized care and new treatment approaches.

Mast cell activation syndrome (MCAS) causes your immune system to send repeated false alarms throughout your body, triggering severe episodes of swelling, breathing problems, skin reactions, and digestive symptoms without a clear reason.

Mastocytosis is a rare disease that happens when the body produces too many mast cells, which are white blood cells that normally protect against bacteria and allergens. When these cells become abnormal and multiply uncontrollably, they release chemicals that cause unusually intense or long-lasting allergic reactions throughout the body.

Measles is one of the most contagious diseases known to humans, capable of spreading rapidly through communities and causing serious, sometimes fatal, complications—but it can be prevented with a safe and effective vaccine.

Mechanical ventilation is a life-saving therapy that helps you breathe when your body cannot do it on its own. Whether during surgery or due to serious illness, a ventilator supports your lung function by delivering oxygen and removing carbon dioxide, giving your body the time it needs to heal.

Medical device site joint infection, also known as periprosthetic joint infection, is a serious complication that can occur when bacteria contaminate an artificial joint implant. Although it affects only a small percentage of patients who undergo joint replacement surgery, this infection can lead to significant pain, multiple surgeries, and lasting impact on quality of life.

Medication overuse headache is a challenging condition where the very medicines taken to relieve headaches actually cause more frequent and persistent head pain, creating a difficult cycle that affects around 1-2% of people worldwide.

Medullary thyroid cancer is a rare form of thyroid cancer that develops in special cells inside the thyroid gland. While it accounts for only a small percentage of thyroid cancers, understanding this condition is important because it behaves differently from other thyroid cancers and may run in families.

Medulloblastoma is a cancerous brain tumor that begins in the cerebellum, the part of the brain responsible for balance and coordination. Though it can occur at any age, it is the most common malignant brain tumor in children, with most cases diagnosed between ages 5 and 9.

When medulloblastoma returns after treatment, families face one of the most difficult challenges in pediatric cancer. While initial diagnosis carries an 80% survival rate, recurrence drops survival odds to just 5%, with no established treatment plan available.

Recurrent melanoma means that cancer cells have survived the initial treatment and the disease has returned. Understanding what recurrence means, where it can appear, and how it’s managed is crucial for anyone who has been treated for melanoma.

MELAS syndrome is a rare inherited condition that primarily affects the nervous system and muscles, usually appearing in childhood and causing stroke-like episodes, seizures, and a buildup of lactic acid in the body.

Meniere’s disease is a disorder of the inner ear that causes sudden episodes of severe dizziness, hearing loss, ringing in the ears, and a feeling of fullness or pressure in the ear. While there is no cure, various treatments can help manage symptoms and improve quality of life.

A meningioma is a tumor that grows from the protective layers covering the brain and spinal cord. While most are slow-growing and not cancerous, they can cause serious problems depending on their size and location.

Malignant meningioma is a rare and aggressive form of brain tumor that grows quickly and requires prompt treatment. Though most meningiomas are noncancerous, these cancerous tumors demand specialized care and close monitoring.

Meningococcal infection is a rare but serious bacterial disease that can turn deadly within hours. Early recognition and rapid treatment can save lives, yet many people mistake its early symptoms for a common cold or flu.

Meningorrhagia is a serious medical condition involving bleeding in or around the protective membranes of the brain and spinal cord, a condition that requires immediate medical attention and can have life-threatening consequences.

A meniscus tear is one of the most common knee injuries, affecting athletes and older adults alike. This injury occurs when the tough, rubbery cartilage that cushions your knee becomes torn, causing pain, swelling, and difficulty moving your knee normally.

Meniscus surgery is a common procedure that treats torn cartilage inside your knee. Whether the surgeon repairs the tear with stitches or removes the damaged portion, the operation aims to reduce pain, improve stability, and help you return to your daily activities.

Menopause is a natural life transition that occurs when menstrual periods stop permanently, typically between ages 45 and 55. While it’s a normal part of aging, the physical and emotional changes that come with shifting hormone levels can significantly affect daily life, relationships, and work for many women.

Menopause marks a natural turning point in a woman’s life when menstrual periods stop permanently. While this transition brings hormonal changes that can affect physical and emotional well-being, understanding what happens and knowing your options can help you navigate this stage with confidence.

Mental disorders are conditions that affect how you think, feel, and behave, and they are more common than you might imagine—about 1 in every 7 people worldwide lives with one. These conditions can disrupt daily life, but with proper care and support, many people successfully manage their symptoms and lead fulfilling lives.

Merycism, also known as rumination syndrome, is a chronic condition where undigested food repeatedly comes back up from the stomach into the mouth shortly after eating, without nausea or pain—an involuntary reflex that can affect anyone from infants to adults.

Mesothelioma is a rare and aggressive cancer that develops in the thin layer of tissue covering many internal organs. Most cases are linked to asbestos exposure, and symptoms may not appear until decades after contact with this harmful mineral.

Malignant mesothelioma is a rare and aggressive cancer that develops in the thin layer of tissue covering internal organs, most commonly the lungs. This disease is strongly linked to asbestos exposure and can take decades to appear after contact with this harmful mineral.

Recurrent malignant mesothelioma occurs when the cancer returns after treatment and a period of remission, presenting new challenges for patients who must navigate additional treatment options and adjust their approach to living with this aggressive disease.

Metabolic disorders happen when the body’s normal chemical processes don’t work properly, affecting how we break down food for energy or how our cells function. These conditions can range from inherited genetic problems to diseases that develop when organs like the liver or pancreas stop working correctly.

Metabolic dysfunction-associated steatotic liver disease is when too much fat builds up in your liver, affecting more than 30% of people worldwide. It is closely linked to conditions like obesity and type 2 diabetes, but with changes to diet and exercise, the damage can often be slowed or even reversed.

Metabolic dysfunction-associated steatohepatitis is a serious liver disease that develops when too much fat builds up in the liver, causing inflammation and damage. Often called a “silent disease,” it can progress without obvious symptoms for years, potentially leading to severe scarring, liver failure, or liver cancer.