31 Neurocutaneous conditions

A traumatic neuroma is a type of neuroma which results from trauma to a nerve, usually during a surgical procedure. The most common oral locations are on the tongue and near the mental foramen of the mouth. They are relatively rare on the head and neck.

Body dysmorphic disorder (BDD), occasionally still called dysmorphophobia, is a mental disorder characterized by the obsessive idea that some aspect of one's own body part or appearance is severely flawed and therefore warrants exceptional measures to hide or fix it. In BDD's delusional variant, the flaw is imagined. If the flaw is actual, its importance is severely exaggerated. Either way, thoughts about it are pervasive and intrusive, and may occupy several hours a day, causing severe distress and impairing one’s otherwise normal activities. The DSM-5 categorizes BDD in the obsessive–compulsive spectrum, and distinguishes it from anorexia nervosa.

Body-focused repetitive behavior (BFRB) is an umbrella name for impulse control behaviors involving compulsively damaging one's physical appearance or causing physical injury.

Complex regional pain syndrome (CRPS), also known as reflex sympathetic dystrophy (RSD), describes an array of painful conditions that are characterized by a continuing regional pain that is seemingly disproportionate in time or degree to the usual course of any known trauma or other lesion. Usually starting in a limb, it manifests as extreme pain, swelling, limited range of motion, and changes to the skin and bones. It may initially affect one limb and then spread throughout the body; 35% of affected people report symptoms throughout their whole bodies. Two subtypes exist. Having both types is possible.

Congenital insensitivity to pain with anhidrosis (CIPA) is a rare autosomal recessive disorder of the nervous system which prevents the feeling of pain or temperature, and prevents a person from sweating. Cognitive disorders are commonly coincident. CIPA is the fourth type of hereditary sensory and autonomic neuropathy (HSAN), and is also known as HSAN IV.

Factitious dermatitis is a form of factitious disorder in which patients will intentionally feign symptoms and produce signs of disease in an attempt to assume the patient role. It is also self-inflicted skin damage, most commonly from prolonged deliberate scratching, but sometimes by means of sharp instruments or another agency.

Dermatophagia is a compulsion disorder of gnawing or biting one's own skin, most commonly at the fingers. This action can either be conscious or unconscious. Those affected with dermatophagia typically bite the skin around the nails, leading to bleeding and discoloration over time. Some people also bite on their skin on their finger knuckles which can lead to pain and bleeding just by moving their fingers. It has been proposed that dermatodaxia would be a more fitting term for this disorder, as the suffix-phagia' implies that the skin is being eaten rather than simply bitten. In most cases of dermatophagia in humans, the skin is only bitten with no consumption. In herpetology, dermatophagia is used to correctly describe the act in which amphibians and reptiles eat the skin they shed, but this is not what occurs in humans. Those diagnosed with this disorder do not develop wounds on the bitten areas of their hands or lose any skin. Instead, they experience a thickening of the skin being repeatedly bitten. This information implies that the skin is simply being bitten and chewed rather than eaten. Contemporary research suggests a link between impulse control disorders and obsessive–compulsive disorders, and this was addressed in the DSM-5 when dermatophagia and other related disorders were classified as 'other specified obsessive-compulsive related disorders' and are given the specification of body focused repetitive behavior. Further information on OCD, other anxiety disorders, dermatophagia and other related body focused repetitive behaviors can be found in the DSM-5

Body dysmorphic disorder (BDD), occasionally still called dysmorphophobia, is a mental disorder characterized by the obsessive idea that some aspect of one's own body part or appearance is severely flawed and therefore warrants exceptional measures to hide or fix it. In BDD's delusional variant, the flaw is imagined. If the flaw is actual, its importance is severely exaggerated. Either way, thoughts about it are pervasive and intrusive, and may occupy several hours a day, causing severe distress and impairing one’s otherwise normal activities. The DSM-5 categorizes BDD in the obsessive–compulsive spectrum, and distinguishes it from anorexia nervosa.

Excoriation disorder is an obsessive-compulsive spectrum mental disorder that is characterized by the repeated urge or impulse to pick at one's own skin to the extent that either psychological or physical damage is caused.

Factitious dermatitis is a form of factitious disorder in which patients will intentionally feign symptoms and produce signs of disease in an attempt to assume the patient role. It is also self-inflicted skin damage, most commonly from prolonged deliberate scratching, but sometimes by means of sharp instruments or another agency.

Notalgia paraesthetica (NP) or notalgia paresthetica is a chronic sensory neuropathy. Notalgia paraesthetica is a common localized itch, affecting mainly the area between the shoulder blades but occasionally with a more widespread distribution, involving the shoulders, back, and upper chest. The characteristic symptom is pruritus on the back, usually on the left hand side below the shoulder blade. It is occasionally accompanied by pain, paresthesia, or hyperesthesia, which results in a well circumscribed hyperpigmentation of a skin patch in the affected area.

Levator ani syndrome is a condition characterized by brief intermittent burning pain or tenesmus of the rectal or perineal area, caused by spasm of the levator ani muscle. The genesis of the syndrome is unknown; however, inflammation of the arcus tendon is a possible cause of levator ani syndrome.

Malum perforans is a long-lasting, usually painless ulcer that penetrates deep into or through the skin, usually on the sole of the foot. It is often a complication in diabetes mellitus and other conditions affecting the nerves.

Nail biting, also known as onychophagy or onychophagia, is an oral compulsive habit of biting one's fingernails. It is sometimes described as a parafunctional activity, the common use of the mouth for an activity other than speaking, eating, or drinking.

Malum perforans is a long-lasting, usually painless ulcer that penetrates deep into or through the skin, usually on the sole of the foot. It is often a complication in diabetes mellitus and other conditions affecting the nerves.

Notalgia paraesthetica (NP) or notalgia paresthetica is a chronic sensory neuropathy. Notalgia paraesthetica is a common localized itch, affecting mainly the area between the shoulder blades but occasionally with a more widespread distribution, involving the shoulders, back, and upper chest. The characteristic symptom is pruritus on the back, usually on the left hand side below the shoulder blade. It is occasionally accompanied by pain, paresthesia, or hyperesthesia, which results in a well circumscribed hyperpigmentation of a skin patch in the affected area.

Parry–Romberg syndrome (PRS) is a rare disease characterized by progressive shrinkage and degeneration of the tissues beneath the skin, usually on only one side of the face but occasionally extending to other parts of the body. An autoimmune mechanism is suspected, and the syndrome may be a variant of localized scleroderma, but the precise cause and pathogenesis of this acquired disorder remains unknown. It has been reported in the literature as a possible consequence of sympathectomy. The syndrome has a higher prevalence in females and typically appears between 5 and 15 years of age.

Malum perforans is a long-lasting, usually painless ulcer that penetrates deep into or through the skin, usually on the sole of the foot. It is often a complication in diabetes mellitus and other conditions affecting the nerves.

Notalgia paraesthetica (NP) or notalgia paresthetica is a chronic sensory neuropathy. Notalgia paraesthetica is a common localized itch, affecting mainly the area between the shoulder blades but occasionally with a more widespread distribution, involving the shoulders, back, and upper chest. The characteristic symptom is pruritus on the back, usually on the left hand side below the shoulder blade. It is occasionally accompanied by pain, paresthesia, or hyperesthesia, which results in a well circumscribed hyperpigmentation of a skin patch in the affected area.

Complex regional pain syndrome (CRPS), also known as reflex sympathetic dystrophy (RSD), describes an array of painful conditions that are characterized by a continuing regional pain that is seemingly disproportionate in time or degree to the usual course of any known trauma or other lesion. Usually starting in a limb, it manifests as extreme pain, swelling, limited range of motion, and changes to the skin and bones. It may initially affect one limb and then spread throughout the body; 35% of affected people report symptoms throughout their whole bodies. Two subtypes exist. Having both types is possible.

Notalgia paraesthetica (NP) or notalgia paresthetica is a chronic sensory neuropathy. Notalgia paraesthetica is a common localized itch, affecting mainly the area between the shoulder blades but occasionally with a more widespread distribution, involving the shoulders, back, and upper chest. The characteristic symptom is pruritus on the back, usually on the left hand side below the shoulder blade. It is occasionally accompanied by pain, paresthesia, or hyperesthesia, which results in a well circumscribed hyperpigmentation of a skin patch in the affected area.

Syringomyelia is a generic term referring to a disorder in which a cyst or cavity forms within the spinal cord. This cyst, called a syrinx, can expand and elongate over time, destroying the spinal cord. The damage may result in loss of feeling, paralysis, weakness, and stiffness in the back, shoulders, and extremities. Syringomyelia may also cause a loss of the ability to feel extremes of hot or cold, especially in the hands. It may also lead to a cape-like bilateral loss of pain and temperature sensation along the upper chest and arms. Each patient experiences a different combination of symptoms. These symptoms typically vary depending on the extent and, often more critically, on the location of the syrinx within the spinal cord.

Trigeminal neuralgia is a long-term pain disorder that affects the trigeminal nerve. It is a form of neuropathic pain. There are two main types: typical and atypical trigeminal neuralgia. The typical form results in episodes of severe, sudden, shock-like pain in one side of the face that lasts for seconds to a few minutes. Groups of these episodes can occur over a few hours. The atypical form results in a constant burning pain that is less severe. Episodes may be triggered by any touch to the face. Both forms may occur in the same person. It is regarded to be one of the most painful disorders known to medicine, and often results in depression..

A traumatic neuroma is a type of neuroma which results from trauma to a nerve, usually during a surgical procedure. The most common oral locations are on the tongue and near the mental foramen of the mouth. They are relatively rare on the head and neck.

Trichotillomania (TTM), also known as hair pulling disorder or compulsive hair pulling, is a mental disorder characterized by a long-term urge that results in the pulling out of one's hair. This occurs to such a degree that hair loss can be seen. A brief positive feeling may occur as hair is removed. Efforts to stop pulling hair typically fail. Hair removal may occur anywhere; however, the head and around the eyes are most common. The hair pulling is to such a degree that it results in distress.

Trigeminal neuralgia is a long-term pain disorder that affects the trigeminal nerve. It is a form of neuropathic pain. There are two main types: typical and atypical trigeminal neuralgia. The typical form results in episodes of severe, sudden, shock-like pain in one side of the face that lasts for seconds to a few minutes. Groups of these episodes can occur over a few hours. The atypical form results in a constant burning pain that is less severe. Episodes may be triggered by any touch to the face. Both forms may occur in the same person. It is regarded to be one of the most painful disorders known to medicine, and often results in depression..

Trigeminal trophic syndrome is a rare disease caused by the interruption of peripheral or central sensory pathways of the trigeminal nerve. A slowly enlarging, uninflammed ulcer can occur in the area that has suffered the trigeminal nerve damage; including but not limited to the cheek beside the ala nasi. These sores affect the skin supplied by the sensory component of the trigeminal nerve. Similar lesions may also occur in the corners of the eyes, inside the ear canal, on the scalp or inside the mouth.

Malum perforans is a long-lasting, usually painless ulcer that penetrates deep into or through the skin, usually on the sole of the foot. It is often a complication in diabetes mellitus and other conditions affecting the nerves.

X-linked agammaglobulinemia (XLA) is a rare genetic disorder discovered in 1952 that affects the body's ability to fight infection. As the form of agammaglobulinemia that is X-linked, it is much more common in males. In people with XLA, the white blood cell formation process does not generate mature B cells, which manifests as a complete or near-complete lack of proteins called gamma globulins, including antibodies, in their bloodstream. B cells are part of the immune system and normally manufacture antibodies, which defend the body from infections by sustaining a humoral immunity response. Patients with untreated XLA are prone to develop serious and even fatal infections. A mutation occurs at the Bruton's tyrosine kinase (Btk) gene that leads to a severe block in B cell development and a reduced immunoglobulin production in the serum. Btk is particularly responsible for mediating B cell development and maturation through a signaling effect on the B cell receptor BCR. Patients typically present in early childhood with recurrent infections, in particular with extracellular, encapsulated bacteria. XLA is deemed to have a relatively low incidence of disease, with an occurrence rate of approximately 1 in 200,000 live births and a frequency of about 1 in 100,000 male newborns. It has no ethnic predisposition. XLA is treated by infusion of human antibody. Treatment with pooled gamma globulin cannot restore a functional population of B cells, but it is sufficient to reduce the severity and number of infections due to the passive immunity granted by the exogenous antibodies.