Phaeochromocytoma is a rare tumor that develops in the adrenal glands and causes the body to produce too much adrenaline, leading to high blood pressure, headaches, and other serious symptoms that can be life-threatening if not treated.

Pharyngeal cancer stage I is an early form of cancer that starts in the pharynx, the middle part of your throat. At this stage, the cancer is small and has not spread, which means there are several effective treatment options available.

Stage II pharyngeal cancer is a middle-stage cancer where the tumor is larger than 2 centimeters but no larger than 4 centimeters, and treatment options include surgery, radiation therapy, or a combination of treatments depending on the specific location in the throat.

Stage 3 pharyngeal cancer represents an advanced form of throat cancer where the tumor has grown larger or spread to nearby lymph nodes, requiring comprehensive treatment approaches that often combine multiple therapies.

Phenylketonuria is a rare inherited disorder that, without treatment, can cause serious brain damage. With early diagnosis through newborn screening and lifelong management, people with PKU can live healthy, full lives.

Philadelphia chromosome positive is a genetic abnormality that occurs when two chromosomes in the body swap pieces, creating a harmful protein that causes certain blood cancers. This condition is found in most cases of chronic myeloid leukemia and in some cases of acute lymphoblastic leukemia, primarily affecting adults.

Philadelphia positive acute lymphocytic leukaemia is a serious blood cancer that has seen dramatic improvements in treatment and survival rates thanks to modern targeted therapies that have transformed what was once considered nearly incurable into a disease with much better outcomes.

Philadelphia chromosome-positive chronic myeloid leukaemia is a rare blood cancer that occurs when pieces of two chromosomes swap places, creating an abnormal chromosome that changes how white blood cells grow in the bone marrow.

Pigmentary glaucoma is a form of eye disease that often strikes at a younger age than typical glaucoma, primarily affecting people in their twenties to forties. It occurs when tiny pigment particles from the colored part of the eye break loose and clog the drainage system, potentially leading to vision loss if left untreated.

PIK3CA-related overgrowth spectrum (PROS) is a group of rare conditions that cause unusual growth in different parts of the body. These conditions share a common cause: changes in a gene called PIK3CA that controls how cells grow and divide.

PIK3CA-activated mutations are among the most common genetic changes found in cancer, affecting how cells grow, divide, and survive. These mutations lead to increased activity of a key protein that helps control cell growth, which can contribute to tumor development and affect how well certain treatments work.

Piriformis syndrome causes pain in the buttocks that can travel down the leg. It happens when a small muscle deep in your buttock presses on your sciatic nerve. While not very common, affecting only about 0.3% to 6% of people with lower back pain, it can significantly impact your daily activities.

Benign pituitary tumours are unusual growths in the pituitary gland that are not cancer and grow slowly, but they can affect your hormone levels and cause various health problems throughout your body.

Pituitary-dependent Cushing’s syndrome is a rare hormonal disorder that occurs when a tumor in the pituitary gland causes the body to produce too much cortisol, leading to changes in appearance, weight gain, and numerous health complications.

Placenta praevia is a pregnancy complication where the placenta blocks the exit for the baby, affecting about 1 in 200 pregnancies and requiring careful management to protect both mother and child.

Plasma cell leukaemia is the rarest and most aggressive form of plasma cell cancers, where abnormal plasma cells circulate through the bloodstream instead of staying confined to bone marrow as in typical multiple myeloma.

Plasma cell myeloma is a cancer that develops in a type of white blood cell called a plasma cell, where abnormal cells build up in bone marrow and can affect bones, kidneys, and blood cells throughout the body.

When multiple myeloma comes back after treatment, it is called relapsed or recurrent myeloma. Most people with this disease will experience several cycles of remission and relapse throughout the course of their illness, requiring ongoing treatment to control symptoms and improve quality of life.

When multiple myeloma stops responding to treatment or never responds at all, doctors call it refractory myeloma. This challenging form of the disease requires new treatment strategies and ongoing monitoring to manage symptoms and slow progression.

Plasmablastic lymphoma is a rare and aggressive type of cancer that affects white blood cells. It poses significant challenges in diagnosis and treatment, often occurring in people with weakened immune systems, particularly those with HIV infection.

Pleomorphic leiomyosarcoma is a rare and aggressive form of cancer that develops in smooth muscle tissue, characterized by cancer cells that vary greatly in size and shape, making it particularly challenging to diagnose and treat.

Pleomorphic liposarcoma is a rare and aggressive cancer that develops in fat tissue, most commonly in the arms and legs. It is the least common but most aggressive type of liposarcoma, characterized by abnormally shaped fat cells and a high risk of spreading to other parts of the body.

Pleural mesothelioma is a rare and aggressive cancer that forms in the lining of the lungs and chest wall, caused primarily by asbestos exposure, often decades before symptoms appear.

Pleural mesothelioma malignant is a rare and aggressive cancer that develops in the tissue lining the lungs and chest wall, almost always linked to asbestos exposure that may have occurred decades earlier.

Recurrent pleural mesothelioma occurs when this rare cancer returns after treatment. While this aggressive disease poses serious challenges, understanding available treatment options and living with recurrence can help patients make informed decisions about their care.

Pneumococcal infection is a serious bacterial disease caused by Streptococcus pneumoniae that can affect people of all ages, causing illnesses ranging from ear infections to life-threatening pneumonia and meningitis.

Pneumonia is a lung infection that causes inflammation and fluid buildup in the air sacs, making it hard to breathe. While it can affect anyone, it poses the greatest risk to young children, older adults, and people with certain health conditions.

Bacterial pneumonia is a serious lung infection that can range from mild to life-threatening, affecting millions of people each year and requiring prompt medical attention to prevent complications and ensure full recovery.

Chlamydia pneumoniae is a type of bacteria that can cause respiratory infections ranging from mild cold-like symptoms to more serious pneumonia, though most people recover on their own without treatment.

A pneumothorax, commonly called a collapsed lung, occurs when air leaks into the space between your lung and chest wall, causing the lung to deflate and leading to sudden chest pain and breathing difficulties that require immediate medical attention.

Polycystic liver disease is a rare genetic condition where numerous fluid-filled sacs develop throughout the liver, often without symptoms but sometimes causing significant discomfort as the cysts grow larger over time.

Polycystic ovary syndrome affects millions of women worldwide, causing irregular periods, hormonal imbalances, and fertility challenges—yet up to 70% of cases remain undiagnosed.

Polycythaemia vera is a rare blood cancer that causes your bone marrow to produce too many red blood cells, making your blood thicker and increasing the risk of serious complications like blood clots, heart attack, and stroke.

Polymyalgia rheumatica is an inflammatory condition that causes sudden pain and stiffness in the shoulders, neck, and hips, mainly affecting people over 50 years of age.

Polymyositis is a rare disease that causes your immune system to attack your muscles, leading to chronic inflammation and weakness that affects both sides of the body. While there is no cure, understanding the condition and available treatments can help you manage symptoms and maintain your quality of life.

Polyneuropathy is a condition where multiple peripheral nerves throughout the body become damaged at the same time, causing problems with sensation, movement, or other body functions. It affects between 1% and 7% of people in the United States, with higher rates among those over 50 years of age.

Polypoidal choroidal vasculopathy is a disease affecting the blood vessel layer beneath the retina, causing fluid leakage and bleeding that can lead to vision loss if left untreated. While it shares features with age-related macular degeneration, this condition requires specialized diagnosis and treatment approaches.

Poor quality sleep affects millions of people, disrupting daily life and contributing to serious health problems. Understanding what defines poor sleep and how to improve it can make a significant difference in your overall health and wellbeing.

Non-acute porphyrias are a group of rare inherited conditions that primarily affect the skin, causing it to become sensitive to sunlight and leading to symptoms like pain, blistering, and scarring in sun-exposed areas.

Portal hypertension is a serious complication that develops when blood pressure rises dangerously high in the portal vein, the major vessel that carries blood from your digestive organs to your liver. This condition, most commonly caused by liver scarring from cirrhosis, can lead to life-threatening internal bleeding and other severe complications that require careful medical management.

Porto-sinusoidal vascular disorder is a rare liver condition that causes increased pressure in the blood vessels of the liver without the presence of cirrhosis, often remaining undetected until serious complications arise.

Chronic pain after breast surgery affects between 20 and 68% of women who have undergone breast procedures, significantly impacting their quality of life and daily activities.

Post cardiac arrest syndrome is a serious condition that can develop after a person’s heart is successfully restarted following cardiac arrest. This complex medical situation affects multiple organs throughout the body and requires immediate, specialized care to improve chances of survival and recovery.

Post procedural complications are unwanted or unexpected conditions that develop after a surgical procedure or medical intervention. These complications can occur immediately after surgery or even years later, affecting recovery and overall health outcomes.

Low blood pressure after surgery is a common problem that can lead to serious complications if not properly managed. Understanding its causes and knowing how to respond can help patients recover safely.

An infection after surgery is a complication that can occur when bacteria enter the body through surgical incisions. While healthcare providers take strict precautions to prevent these infections, they remain a significant concern, affecting between 1 and 3 out of every 100 surgical patients and contributing to increased hospital stays, healthcare costs, and health complications.

Swelling after surgery is one of the most common experiences patients face during recovery, yet understanding what’s happening in your body and how to manage it can significantly improve your healing journey and overall comfort.

Post procedural pulmonary embolism is a serious and potentially life-threatening complication that can occur after surgical procedures, ranking as the third most common cause of cardiovascular death worldwide.

Swelling after surgery is a normal part of healing, but understanding what causes it and how to manage it can make your recovery smoother and more comfortable.

Post transplant lymphoproliferative disorder (PTLD) is a rare but serious complication that can develop after organ or stem cell transplant, when white blood cells multiply uncontrollably due to a weakened immune system.

Post-acute COVID-19 syndrome is a condition where symptoms continue or develop weeks, months, or even years after recovering from the initial COVID-19 infection, affecting multiple organs and significantly impacting daily life.

Post-traumatic headache is one of the most common symptoms following a head injury, affecting up to 90% of people who experience traumatic brain injury. While most people recover within weeks, some continue to experience debilitating headaches for months or even years after the initial injury.

Post-traumatic stress disorder (PTSD) is a mental health condition triggered by extremely stressful or frightening events. While most people experience distress after trauma, some develop persistent symptoms that can significantly affect their daily lives—but effective treatments are available that can help people recover.

Postoperative delirium is the most common complication of surgery for older adults, affecting up to half of seniors who undergo operations. This sudden change in mental function—ranging from confusion and disorientation to agitation or unusual sleepiness—typically occurs within hours to days after surgery and can significantly impact recovery if not recognized and managed properly.

Surgery can save lives, but infections at the surgical site remain a common complication that affects millions of patients each year, increasing hospital stays and healthcare costs while threatening recovery.

Postpartum haemorrhage is severe bleeding after childbirth that affects up to 5 in every 100 women, but with early detection and proper treatment, most people make a full recovery.

Postprandial hypoglycaemia, also known as reactive hypoglycemia, is a condition where blood sugar drops too low within a few hours after eating a meal. While it shares similar symptoms with other types of low blood sugar, this condition has distinct causes and requires specific dietary approaches for management.

Postural orthostatic tachycardia syndrome (POTS) is a condition that causes your heart to beat much faster than normal when you stand up, leading to dizziness, exhaustion, and many other symptoms that can significantly impact daily life.

Pouchitis is inflammation that develops inside an ileal pouch, a surgically created internal reservoir made from the small intestine. It’s the most common complication after pouch surgery, affecting between 25% and 45% of people who have this procedure. While most cases respond well to treatment with antibiotics, some people experience ongoing or recurring inflammation that becomes more challenging to manage.

Prader-Willi syndrome is a rare genetic disorder that transforms through a person’s lifetime—beginning with weak, floppy infants who struggle to feed, then shifting dramatically in childhood to an insatiable appetite that never signals fullness, leading to one of the most challenging aspects of care: constant food supervision to prevent life-threatening obesity.