Online Nursing Library: A Guide to the World's Strangest and Rarest Diseases

Nurses care for patients with a variety of injuries and illnesses each day, but many of these illnesses are the same ones that a nurse sees many times in his or her career. However, there are a number of rare diseases that many nurses never get to see. These diseases cause unusual physical and psychological symptoms and often stump medical professionals when it comes to making a diagnosis. The chance to see one of these diseases in a clinical setting is one of the most exciting opportunities available to nurses. Learning about these diseases can help nursing professionals know what to look for in their own patients.

Blaschko Lines

Blaschko Lines Forming by Filip Em.

Everyone is born with Blaschko lines, which are invisible lines that represent how the skin cells migrated during the development of a fetus. In people who have skin diseases, however, these lines in the skin become visible. This causes the appearance of unusual patterns on the face, limbs, and other parts of the body. These lines are named after Alfred Blaschko, a German dermatologist who spoke about them at a professional conference in 1901.

  • Blaschko Lines: The New Zealand Dermatological Society explains what Blaschko lines are and where the term originated.
  • Photos of Blaschko Lines: The Dermatology Online Journal shows what Blaschko lines look like on a portion of the skin.


Progeria Syndrome by PLOS.

Progeria, also called Hutchinson-Gilford progeria syndrome, is a rare genetic condition that causes children to age rapidly. This condition causes growth failure, wrinkled face, baldness, short statute, large head, small jaws, limited range of motion, delayed formation of teeth or missing teeth, thin skin, open soft spots on the head, and loss of the eyebrows and eyelashes. Children with progeria may develop complications such as stroke, heart attack, and insulin resistance. The genetic cause of progeria is a mutation in the gene known as lamin A.

  • Progeria: PubMed Health provides an overview of progeria and explains how it is diagnosed.
  • Learning About Progeria: The National Human Genome Research Institute explains the genetic aspects of progeria.

Fibrodysplasia Ossificans Progressiva

fibrodysplasia-ossificans-progressiva by Joh-co.

Fibrodysplasia ossificans progressive is one of the rarest conditions in medicine. This genetic disease causes bones to form where they should not. Bones can form in the muscles, joints, ligaments, and tendons. This bone formation results in a second skeleton, which traps the body in bone and restricts the movement of those who have the disease. This disease occurs due to a mutation of the ACVR1 gene, which gives instructions for producing bone morphogenetic protein type I receptors. The mutation changes the shape of the receptors and alters their activity. This causes the overgrowth of bone and the fusion of the joints.

Necrotizing Fasciitis

Necrotizing Fasciitis photo by Piotr Smuszkiewicz, Iwona Trojanowska and Hanna Tomczak.

Often called “flesh-eating bacteria,” necrotizing fasciitis is a serious condition that occurs when an infection causes the breakdown of muscle and fat tissue. This condition affects only 10,000 to 15,000 people each year in the U.S., but it results in 2,000 to 3,000 deaths. Death occurs when bacteria from the infection get into the bloodstream, which causes sepsis. Nurses play an important role in preventing necrotizing fasciitis, as proper wound care is one way to help prevent the condition.

  • Necrotizing Fasciitis: The CDC describes necrotizing fasciitis and provides statistics about its prevalence in the United States.
  • Necrotizing Fasciitis Fact Sheet: The National Necrotizing Fasciitis Foundation explains where this “flesh-eating” bacterium comes from and how it is contracted.

Werewolf Syndrome

Petrus Gonsalvus.

Although werewolves are usually found in fiction books, one rare condition causes people to take on the appearance of werewolves because they are covered with hair. Werewolf syndrome, also known as congenital hypertrichosis, causes excess hair to grow all over the body. This is a genetic condition that may be caused by spontaneous gene mutation.

Aquagenic Urticaria

Urticaria by James Heilman, MD.

Aquagenic urticaria, also called aquagenic pruritus, is a rare condition that causes the skin to itch after exposure to water. Sweating, taking a shower, or getting splashed with a few drops of water from a drinking glass can provoke the reaction. In addition to itching, someone with aquagenic urticaria may experience burning and prickling of the skin. In some people, a bumpy rash appears on the skin. Although researchers do not know the exact cause of this condition, some suspect it is a reaction to minerals in the water and not the water itself.

  • Pruritus: Dr. Scott Moses explains the different types of pruritus and gives information about their causes.


Elephanti by O. G. Mason - Fox, George Henry. Photographic illustrations of skin diseases. E. B. Treat, New York, 1880. Licensed under Public Domain via Commons.

Elaphantiasis, also known as lymphatic filariasis, is a tropical disease caused by a parasite. Mosquitoes transmit the parasites to humans by biting and depositing the parasites on the skin. This allows the parasites to migrate to the lymphatic system and form nests as they grow into adult worms. This condition causes significant disfigurement and, if not treated, permanent disability.

  • Lymphatic Filariasis: The World Health Organization explains what causes elephantiasis and provides statistics about the disease.
  • Lymphatic Filariasis Diagnosis: The Centers for Disease Control and Prevention explains how medical professionals diagnose elephantiasis.


"Alice par John Tenniel 11". Licensed under Public Domain via Commons

Micropsia, sometimes called “Alice in Wonderland syndrome,” is a neurological condition that causes objects to appear smaller and farther away than they really are. This causes the person with micropsia to feel larger than he or she really is. Causes of micropsia include use of psychoactive drugs, migraines, eye problems, and optical distortion. In some cases, it occurs when someone has Epstein-Barr virus or epilepsy.

Cotard's Syndrome

Jules Cotard.

Cotard's syndrome is a psychiatric condition that causes delusions of despair. People affected by these delusions sometimes believe that they are dead, decomposing, and/or are missing their organs or their blood. In other occurrences the affected person believed that they didn't exist at all. It is often found in people who are middle-aged or elderly. When reported in young people, it is usually females who are affected by Cotard’s syndrome. The condition is named after Jules Cotard, a psychiatrist who treated several patients who exhibited the characteristic delusions.


Glore Stomach Display by MetalSlugX at en.wikipedia. Licensed under Public Domain via Commons.

Pica is an unusual disorder that causes people to eat non-food substances such as chalk, clay, dirt, feces, paper, soap, mucus, and soil. Pica does not refer to one or two isolated incidents of eating non-food items. The disorder must persist for at least a month before it can be diagnosed as pica. It is more common in women than in men, and it is also more common in children than adults. One of the risks of pica is that those with the condition may eat items that contain high amounts of lead, causing lead poisoning and brain damage. In some cases, pica is caused by an underlying mineral deficiency. It can also be caused by obsessive-compulsive disorder. The above picture shows 1,440 items found in the stomach of a patient suffering from pica.

Capgras Delusion

Capgras delusion is when someone thinks that loved ones, such as spouses or children, have been replaced by aliens, imposters, or robots. Although this type of delusion usually occurs in the presence of a psychiatric disorder, it can also occur due to brain trauma. Some people with this condition even believe that their pets have been replaced by imposters. This disorder is very rare and researchers do not know the exact cause.


Trichotillomania by Robodoc, Licensed under Public Domain via Commons

Trichotillomania is a disorder that compels people to pull out the hair from their scalps, underarms, and other parts of the body. This causes bald patches to form in the affected areas. Depending on the severity of the condition, trichotillomania may be treated with therapy, as it is an impulse control disorder. Researchers do not know why people pull out their own hair, but some scientists believe that hair-pulling has a calming effect for those who have this disorder.

  • What is Compulsive Hair Pulling?: The Trichotillomania Learning Center explains what trichotillomania is and how it manifests.
  • Trichotillomania: Mental Health America explains the available treatments for this disorder and discusses how it relates to obsessive-compulsive disorder and other psychiatric conditions.


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