Paraneoplastic neurological syndromes are rare conditions that occur when the body’s immune system, while fighting cancer, mistakenly attacks the nervous system, causing symptoms that often appear before the cancer itself is even discovered.

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare blood disorder where the body’s immune system mistakenly attacks and destroys its own red blood cells, leading to serious complications including anaemia, blood clots, and kidney problems.

Pelizaeus-Merzbacher disease is a rare inherited condition that affects the brain and spinal cord, primarily occurring in males. The disease disrupts the body’s ability to produce enough myelin, the protective coating around nerves, leading to problems with movement, balance, and development that worsen over time.

Pemphigoid is a rare blistering condition that mainly affects people over 60 years old. While it can be serious and last for years, proper treatment helps control the symptoms and allows the skin to heal, though it may take time and patience.

Pemphigus is a group of rare autoimmune diseases that cause painful blisters and sores to form on the skin and inside the mouth. While there is no cure, treatments can help control symptoms and allow many people to manage this lifelong condition.

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.

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.

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.

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.

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.

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.

Primary biliary cholangitis is a long-term liver condition where the immune system mistakenly attacks the small tubes in the liver that carry bile, leading to gradual damage that can worsen over time without treatment.

Primary hyperoxaluria is a rare inherited condition where the body produces too much oxalate, leading to recurring kidney stones and potentially life-threatening kidney damage.

Primary immunodeficiency syndrome refers to a large group of disorders where the body’s immune system doesn’t work properly, making it harder to fight off infections and leading to various health complications throughout life.

Primary mediastinal large B-cell lymphoma is a rare and aggressive form of cancer that develops in the chest, primarily affecting young adults and showing a unique tendency to occur more often in women than men.

Progressive multifocal leukoencephalopathy is a rare and often fatal brain infection caused by a common virus that most people carry harmlessly, but which can become dangerous when the immune system is severely weakened.

Progressive supranuclear palsy is a rare brain disease that primarily affects how you walk, move your eyes, think, and swallow. Although it shares some features with Parkinson’s disease, it progresses faster and has unique characteristics that set it apart.

Prolymphocytic leukaemia is a rare and aggressive blood cancer that affects white blood cells. It advances rapidly and primarily affects older adults, making early diagnosis and treatment critical for managing this challenging condition.

Propionic acidaemia is a rare inherited disorder where the body cannot properly break down certain proteins and fats, leading to a dangerous buildup of toxic acids that can cause serious health problems from the first days of life.

Proteus syndrome is one of the world’s rarest genetic conditions, affecting fewer than 1 in 1 million people worldwide. This complex disorder causes some parts of the body to grow abnormally and out of proportion, leading to significant physical differences that worsen over time.

Pulmonary fibrosis is a lung disease where tissue becomes scarred and thickened, making breathing progressively more difficult. While the exact cause is often unknown, understanding this condition and its management can help improve quality of life for those affected.

Pulmonary sarcoidosis is a condition where the immune system overreacts and forms tiny lumps of inflamed cells called granulomas in the lungs, affecting how well you can breathe and causing symptoms that range from mild to severe.

PAPA syndrome is a rare genetic condition that causes recurring joint inflammation, severe skin ulcers, and acne. It typically begins with joint problems in early childhood and develops skin symptoms during the teenage years.