A spermatocele is a fluid-filled sac that develops near the testicle. It’s usually painless, not cancerous, and often goes unnoticed. While most men never need treatment, understanding this common condition can help ease worry if you discover a lump in your scrotum.

Spina bifida is a condition present at birth where the spine and spinal cord don’t develop properly, leaving a gap in the bones of the spine. While it can range from very mild to severe, understanding the condition and available treatments can help families navigate the challenges and support those affected to live full lives.

A spinal cord injury can change almost every aspect of a person’s life in an instant, affecting movement, sensation, and bodily functions. While these injuries present profound challenges, advances in research and rehabilitation are opening new possibilities for recovery and independence.

Cervical spinal cord injuries affect the uppermost section of the spine in the neck and are the most severe of all spinal cord injuries, often leading to significant disability or even paralysis.

Spinal muscular atrophy is a genetic condition that causes progressive muscle weakness and wasting, affecting movement, breathing, and sometimes swallowing. While there is no cure, new treatments are helping people with this condition live longer and better lives.

Spinal osteoarthritis is a breakdown of cartilage in the joints of the spine that causes pain, stiffness, and reduced mobility. While the damage cannot be reversed, various treatments can help manage symptoms and improve quality of life.

Spinal pain affects millions of people worldwide, ranging from mild discomfort to severe disability that impacts everyday activities, work, and quality of life.

Splenic marginal zone lymphoma is a rare, slow-growing type of blood cancer that mainly affects the spleen, and while it often develops gradually without symptoms, it can usually be treated effectively with modern therapies.

When one of the bones in your spine slips out of place and presses on the bone below it, it can cause pain and limit your daily activities. This condition, known as spondylolisthesis, affects thousands of people each year, but many cases can be successfully managed with the right treatment approach.

Squamous cell carcinoma is the second most common type of skin cancer, affecting over 1 million people in the U.S. each year. While usually not life-threatening when caught early, understanding this condition and seeking prompt treatment is essential for the best outcome.

Squamous cell carcinoma of the head and neck is a cancer that develops in the moist tissues lining your mouth, nose, and throat, with most cases linked to tobacco use, heavy alcohol consumption, or infection with human papillomavirus (HPV).

Squamous cell carcinoma of the lung is the second most common type of lung cancer after adenocarcinoma, representing about 25-30% of all lung cancer cases. This type of cancer forms when thin, flat cells lining the airways become damaged and multiply uncontrollably, most often in the central part of the lung.

Squamous cell carcinoma of the skin is the second most common type of skin cancer, developing when squamous cells in the outer layer of skin grow out of control, most often due to sun exposure.

Squamous cell carcinoma of the cervix is the most common type of cervical cancer, accounting for up to 90% of all cases. This cancer develops when cells on the cervix’s surface become abnormal, usually due to infection with the human papillomavirus (HPV). While cervical cancer remains a significant health concern worldwide, it is largely preventable through regular screening and the HPV vaccine.

Squamous cell carcinoma of the hypopharynx is a rare and aggressive throat cancer that often goes unnoticed until it has spread, making early detection and specialized treatment essential for improving survival outcomes.

Squamous cell carcinoma of the oral cavity is a serious cancer affecting the mouth, accounting for more than 90% of all oral malignancies. Early detection is crucial, as this disease often shows no symptoms in its early stages when it is most treatable.

Squamous cell carcinoma of the vagina is a rare but potentially serious cancer that develops in the thin, flat cells lining the vagina. Though it grows slowly, early detection through regular examinations is crucial, as this cancer may not cause symptoms in its early stages.

Squamous cell carcinoma of the vulva is the most common type of vulvar cancer, accounting for about 90% of all vulvar cancers. This rare disease typically affects older women and often causes visible skin changes, itching, or lumps in the genital area. Early detection and treatment can lead to excellent survival rates.

Staphylococcal bacteraemia is a serious bloodstream infection caused by Staphylococcus aureus bacteria, with a 30-day mortality rate of around 20%. This condition can lead to life-threatening complications affecting the heart, bones, lungs, and other vital organs throughout the body.

Staphylococcal infections are caused by bacteria that commonly live harmlessly on the skin or in the nose of many people, but sometimes enter the body and cause problems ranging from minor skin issues to life-threatening conditions.

Stargardt’s disease is a rare genetic eye condition that causes progressive vision loss, usually beginning in childhood or adolescence. It affects about 1 in 10,000 people and is the most common form of inherited juvenile macular degeneration.

Status epilepticus is a life-threatening medical emergency that occurs when seizures last too long or happen one after another without recovery time in between. This dangerous brain condition requires immediate medical attention to prevent permanent brain damage or death.

Stem cell transplants are life-saving procedures that can treat serious blood cancers, blood disorders, and some autoimmune diseases by replacing damaged or diseased blood cells with healthy ones.

Stevens-Johnson syndrome is a rare but serious skin reaction that can threaten your life. It usually starts with symptoms similar to the flu, followed by a painful rash that spreads, blisters, and causes the skin to peel off. Most cases are triggered by medications, though infections can also be responsible.

Still’s disease is a rare inflammatory condition that causes daily high fevers, a distinctive rash, and joint pain. This disease can appear either in childhood or in adults, often making everyday activities challenging and unpredictable.

Stomatitis is inflammation of the mucous membranes lining the mouth or lips, causing pain, redness, and sometimes sores that can make eating, drinking, and talking difficult.

Streptococcal infections are caused by bacteria that can affect your throat, skin, and in rare cases, deeper parts of your body. While most infections are mild and easily treated with antibiotics, understanding the symptoms and when to seek care is important for protecting your health.

Stress is your body’s natural response to changes and challenges. While everyone experiences it, and some stress can even be helpful, too much stress over a long time can harm both your physical and mental health.

Stress cardiomyopathy is a condition where intense emotional or physical stress causes rapid and severe heart muscle weakness that mimics a heart attack, but without blocked arteries.

Stress urinary incontinence is a common condition where everyday movements like coughing, laughing, or exercising cause unwanted urine leakage. While it can feel embarrassing, effective treatments exist—from simple lifestyle changes to specialized exercises and, when needed, medical procedures.

Strongyloidiasis is an infection caused by a parasitic worm that can persist in the body for decades, often without symptoms. While many infected people remain unaware of their condition, the infection can become life-threatening in those with weakened immune systems.

Subacute cutaneous lupus erythematosus is an autoimmune disease that primarily affects the skin, causing distinctive red rashes and lesions on sun-exposed areas of the body. While there is no cure, understanding the condition and working with healthcare providers can help manage symptoms and maintain quality of life.

A subarachnoid haemorrhage is a rare but life-threatening type of stroke that occurs when bleeding happens in the space between the brain and the tissues covering it, often causing a sudden, extremely severe headache that people describe as the worst of their lives.

A subdural haematoma is a serious medical condition where blood collects between the protective layers of the brain, usually following a head injury. While symptoms can appear immediately after trauma, they may also develop gradually over weeks or even months, making this condition particularly challenging to recognize.

Substance use disorder is a treatable mental health condition affecting millions of people. While it can significantly impact your health, relationships, and daily life, recovery is possible with proper support and treatment.

Suicidal ideation affects millions of people each year, involving thoughts about death or ending one’s life that can range from fleeting wishes to detailed planning—but having these thoughts doesn’t mean you will act on them, and help is available.

Superficial spreading melanoma that has reached stage III represents an advanced form of skin cancer where the disease has spread beyond the original skin site to nearby lymph nodes or surrounding tissues, requiring comprehensive treatment approaches.

Stage 4 superficial spreading melanoma represents the most advanced phase of the most common type of melanoma, where the cancer has traveled beyond its original location to distant parts of the body such as the lungs, liver, bones, or brain.

Superficial spreading melanoma is the most common form of melanoma, accounting for approximately 70% of all cases. This type of skin cancer typically grows slowly along the surface of the skin for months or even years before potentially spreading deeper.

Progressive supranuclear palsy is a rare brain disease that causes serious problems with walking, balance, eye movements, and swallowing, often leading to dangerous falls and complications.

Supraventricular tachycardia is a condition where your heart suddenly beats much faster than normal, with the rapid rhythm starting in the upper chambers of your heart. While it’s usually not life-threatening, understanding this condition can help you manage episodes and know when to seek help.

Synovial sarcoma is a rare soft tissue cancer that grows slowly and often goes unnoticed for years. While it most commonly affects young adults near large joints, it can appear almost anywhere in the body, making early detection challenging but crucial for better outcomes.

Metastatic synovial sarcoma occurs when this rare, aggressive cancer spreads beyond its original location to other parts of the body, most commonly the lungs and lymph nodes, significantly impacting survival and treatment options.

When synovial sarcoma returns after initial treatment, patients face new challenges that require careful multidisciplinary management and individualized treatment approaches.

Synovitis is a swelling and inflammation of the thin membrane that lines certain joints in your body. While it’s especially common in people who have arthritis, this condition can also result from injuries or overuse, causing pain, stiffness, and difficulty moving the affected joint.

Syphilis is a bacterial infection that spreads through sexual contact and can cause serious health problems if left untreated. With early detection and proper antibiotic treatment, this infection can be cured before it causes lasting damage to the body.

Systemic candida is a severe fungal infection that occurs when the yeast Candida spreads from its normal locations in the body to internal organs such as the bloodstream, heart, kidneys, or brain. While Candida naturally lives on our skin and inside our bodies without causing harm, certain conditions can allow it to grow out of control and become life-threatening.

A systemic infection is a serious medical condition where an infection spreads throughout the entire body, affecting multiple organs and tissues rather than remaining in one area. When infections reach the bloodstream, they can trigger life-threatening complications that require immediate medical attention.

Systemic lupus erythematosus is a chronic autoimmune disease where the immune system mistakenly attacks healthy tissue throughout the body. While lupus can affect nearly every organ system, advances in treatment and care mean that most people with this condition can now live long, healthy lives with proper management.

Systemic mastocytosis is a rare blood disorder that occurs when abnormal mast cells build up throughout the body, releasing chemicals that cause a continuous allergic response affecting the skin, digestive system, bones, and other organs.

Systemic scleroderma is a rare autoimmune disease that causes the body to produce too much collagen, leading to hardening and thickening of the skin and internal organs. This chronic condition affects multiple parts of the body and requires careful, ongoing management to control symptoms and prevent serious complications.

Systemic sclerosis affecting the lungs is one of the leading causes of death in people with this rare autoimmune disease, occurring in approximately 35-65% of patients and accounting for 20-40% of all systemic sclerosis-related deaths.