Stranger Than Halloween: Rare, Perplexing Conditions

This October 31, many around the world are enjoying the thrill of ghost stories and fear-inducing legends associated with Halloween. But medical textbooks have their own collection of rare and perplexing conditions that can seem almost otherworldly. 
These often misunderstood rare medical phenomena offer unique challenges for patients, and serve as a reminder of the profound diversity of the human condition. 
Alien hand syndrome – Dr Strangelove syndrome  
A rare neurological disorder nicknamed after a 1964 Stanley Kubrick film. Sufferers lose control of one hand, which continues to move and function, apparently with a will of its own. It’s usually due to some form of brain damage.
Apotemnophilia – body integrity identity disorder
A paraphilia featuring a strong desire for body modification, such as amputation or disability, which sufferers believe will help them to feel “complete”. It may lead to self-mutilation.
Argyria – blue skin disorder
This occurs due to toxic deposits of silver in people who are exposed to the metal through their occupations or are taking excess colloidal silver supplements. Mucosal staining can occasionally be caused by dental amalgam; bad news for vampires with tooth decay.
Autophagia – eating one’s own body
Behaviours such as nail biting, hair pulling, or self-chewing, taken to extremes, can lead to some people literally eating parts of themselves, typically pain-sensitive body parts such as fingers. It may occur in various forms of mental disorder.  
Capgras syndrome – delusion of doubles or imposter syndrome
Those afflicted believe that someone close to them has been replaced by an identical duplicate. The condition is usually due to some form of organic brain damage. Violence towards the other person may result.
Cotard’s syndrome – walking corpse syndrome 
Sufferers are convinced that they don’t exist or are dead, dying, rotting, or missing body parts. It may coexist with Capgras syndrome. Although often a component of psychiatric disorder, some cases show changes on neuroimaging.
Ekbom’s syndrome – delusional parasitosis or formication 
A false belief that the skin is infested with creepy crawlies: bugs, lice, fleas, or worms. Those afflicted may scratch themselves to the point of bleeding, and sometimes call pest control to deal with the imagined problem.
Hypertrichosis lanuginosa congenita – werewolf syndrome
This rare autosomal dominant disorder causes uncontrolled hair growth. Cases have been recorded since the Middle Ages, when the unfortunate victims were often exhibited at circuses and paraded around fairs.
Kuru – cannibals’ prion disease
A medical student favourite, kuru was a fatal neurological disease in Papua New Guinea caused by consuming the infected brain matter of dead relatives as part of a ritualistic funerary practice. Kuru is a transmissible spongiform encephalopathy. It largely died out after efforts by the authorities in the latter part of the last century to stamp out cannibalism.
Lazarus effect – raised from the dead 
In this rare phenomenon, someone declared dead spontaneously shows renewed signs of circulation minutes or hours later (autoresuscitation), classically after apparently failed CPR. It’s named after a figure from the New Testament. Unfortunately for most of those affected, the revival miracle doesn’t last.
Locked–in syndrome – pseudocoma
A person is completely paralysed and unable to communicate except for the ability to blink but is fully conscious and aware of their surroundings. Increasingly recognised and profoundly terrifying, the condition can mimic brain death and was first described by Alexandre Dumas in The Count of Monte Cristo.
Lunacy – full moon transformation
The belief that mental illness peaks around the time of a full moon has been prevalent for millennia; Luna was the Roman goddess of the moon. Studies have failed to confirm any such effect, despite various surveys suggesting that many mental health workers believe in it.   
Morgellons disease – fibres extruding from skin
Patients believe that thread-like fibres appearing under the skin cause sensations of itching, crawling, or stinging. Investigations have found associated sores are due to picking or scratching, and the condition may be a form of delusional parasitosis.
Porphyria – mental illness of a king 
This group of rare genetic enzyme disorders leads to a buildup of porphyrins. Symptoms include hypersensitivity to sunlight, itching, blistering, and changes in mental state. For a long time it was believed porphyria was responsible for the intermittent “madness” of King George III, although this has more recently been disputed.
Xeroderma pigmentosum – sunlight aversion
This genetic condition, featuring extreme sensitivity to ultraviolet light, may be one source of vampire legends. Serious consequences can include severe sunburn, ocular complications, neurological degeneration, and a 1000-fold increased risk of cutaneous malignancies.
Dr Sheena Meredith is an established medical writer, editor, and consultant in healthcare communications, with extensive experience writing for medical professionals and the general public. She is qualified in medicine and in law and medical ethics. 
 
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