Lexicon for Atopic Dermatitis

This is a lexicon for Atopic Dermatitis.
Click on a letter and discover all the related terms and their definition.

  • Papillomavirus


    Virus responsible for human papilloma. The main types are warts, laryngeal papillomatosis, and genital warts.
  • Papule


    A solid, raised skin lesion (not liquid filled).
  • Parabens


    This term describes preservative: parahydroxy methyl benzoate, ethyl,  propyl, butyl, de methyl. Parabens are effective against bacteria and fungi, which explains their common use. As with all components of cosmetics, parabens have been the subject of extensive toxicological studies (on their estrogenic and carcinogenic effects) and their use is now considered to be free of danger to health. However, the debate rages on.
  • Passive smoking


    Passive smoking describes the event of being exposed to cigarette smoke, and thus to its harmful consequences, without being a smoker oneself. An example of this would be children whose parents smoke. Passive smoking should especially be avoided for atopy sufferers, as it increases the risk of asthma
  • Patch tests


    The name for epicutaneous tests, carried out by applying suspected substances to the back. This helps diagnose allergic contact eczema. A positive test appears as in a small eczema lesion, which will be visible for 48 to 72 hours after the test is applied.
    The term atopy patch test refers to epicutaneous tests carried out not with contact allergens, but with allergens suspected to play a role in atopic dermatitis, such as dust-mites. Their usefulness is subject to debate.
  • Peri-ocular dermatitis


    Inflammation around the eyes. This is often combined with peri-oral dermatitis
  • Peri-oral dermatitis


    Inflammation (redness) around the mouth. There are many potential causes of peri-oral dermatitis. Paradoxically, it can be a reaction to excessive or inadequate use of dermo-corticosteroids on the face. Peri-oral dermatitis is benign but can be long-lasting. 
  • pH


    A chemical term ranking the acidity or alkalinity of a substance or tissue. The body has a neutral pH, just slightly above 7. The skin is one exception: its pH on the surface is slightly acidic, at around 5.5. This acidity is necessary for the correct function of the epidermal metabolism. Very alkaline soaps (with a high pH) have harmful consequences: irritant effect, and damage to the skin's defense against infection.
  • PH

    PH is used to calculate skin acidity.
    PH in normal skin is 6.5; in dry skin, it is inferior to 6.5.

  • Phenoxyethanol


    Phenoxyethanol is a preservative (see this term). As with all components of cosmetics and excipients in topical treatments, it is subject to very strict regulation. Phenoxyethanol has very low toxicity. However, following some studies, health authorities recently recommended not to use baby wipes containing phenoxyethanol in the name of total safety.
  • Phosphodiesterase


    An enzyme that plays a role in metabolizing cyclic AMP (see this term), an important molecule for cell function.  Phosphodiesterase inhibitors are currently undergoing clinical trials for treatment of asthma and atopic dermatitis.
  • Phospholipids


    Large lipidic molecules, present in cell membranes and in the lipidic layers surrounding corneocytes. They play a role in the barrier function and the skin's permeability. Anomalies in epidermal phospholipids (ceramides) have been observed in atopic dermatitis, and may play a role in the epidermal abnormality that is likely to be the cause of the condition. 
  • Photo-allergy


    Contact allergy aggravated by sun exposure. The most commonly known example is allergic reactions to fragrances: applying a perfume to which the subject is allergic followed by sun exposure causes redness followed by pigmentation to the affected area. 
  • Photo-sensitivity


    An abnormal increase in sensitivity to the sun. This may be caused by certain conditions, or by taking certain medication. Photo-sensitivity is rarely increased in atopic dermatitis. In such cases, the term used is 'photo-aggravation' of atopic dermatitis. 
  • Photo-tests


    Tests to measure sensitivity to the sun. An area of the back is exposed to specific amounts of UVA and UVB. Several techniques may be used depending on the clinical condition being evaluated. The most commonly used test is the MED measure, or Minimum Erythemal Dose. This tests the minimum quantity of UVB exposure to provoke redness (similar to sunburn). MED is expressed in joules per centimeter squared. It varies depending on the phototype (natural skin color) and for certain conditions (photo-dermatitis). These complicated tests are necessary only in rare cases.
  • Photo-therapy


    Treatment for certain skin conditions using ultra-violet radiation. This can involve UVA, UVB, shorter wavelengths, or both. A combination of UVA and an oral psoralene (a photo-sensitizing agent - increases sensitivity to UV) is known as PUVA therapy. PUVA therapy is an effective treatment for psoriasis and some other skin conditions. Photo-therapy may be indicated for atopic dermatitis in older children, adolescents and adults who have not been improved by more common treatments. UVB is most commonly used, or a combination of UVA and UVB. Photo-therapy is generally well tolerated but must be carefully supervised. All kinds of photo-therapy are medical treatments that require special equipment and are carried out by dermatologists. UV treatments used for esthetic results (such as sunbeds) are not medical and are not recommended. Exposure to UV increases the later risk of skin cancer, which is why it should only be carried out under medical control.     
  • Pimecrolimus


    A drug that inhibits calcineurin, in the same family as tacrolimus. It is used in topical treatment for atopic dermatitis. For commercial and/or regulatory reasons, pimecrolimus is not sold in France. In other countries it is sold under the commercial name "Elidel".
  • Placebo


    Placebo is a Latin word meaning "I shall please". The placebo effect describes improvement to conditions or symptoms without any pharmacological cause, but purely by suggestion or psychological effect. A placebo is a tablet with no active ingredients, imitating the form of a drug. In chronic inflammatory dermatitis conditions such as atopic dermatitis, the placebo effect can be significant. Therefore before confirming that a treatment is effective, it must be proven to obtain better results than a placebo or "fake drug". The placebo effect requires that neither the patient nor his or her doctor knows that the drug being taken is not effective. This is the principle of therapeutic studies known as 'double blind'.  


    The SCORAD rating (see this term) is the most commonly used technique for measuring the severity of atopic dermatitis. The scores are measured by a doctor. PO-SCORAD means SCORAD carried out by the patient themselves (Patient-Oriented). Using stock images and precise explanations, the patients, including even (older) children, are able to score the various symptoms of their atopic dermatitis (erythema, vesicles, etc.), as well as its spread, itching and impact on sleep. The PO-SCORAD has a double use. Firstly, it teaches patients to understand and be accurate when describing the symptoms of atopic dermatitis; and secondly, it can be carried out more frequently, for example once a week, and informs the doctor of the condition's development (flare-ups, remission, etc.) between consultations.   
  • Pollinosis


    A respiratory allergy to pollen, the reproductive parts of certain plants (grass, birch, pine, etc.), which are transported in the air. 
    Pollinosis is also known as allergic rhinitis, or hay-fever, involving rhino-conjunctivitis or asthma. Pollen has a well-known geographical distribution and an exact seasonal pattern. 
  • Pollution


    A general term to describe alterations to the environment caused by industrial activity, urban environments, traffic, etc.  The role of pollution in skin diseases is likely minor, and impossible to prove. 
  • Prebiotics


    Prebiotics are sugars used by probiotics (non-pathogenic intestinal bacteria) to grow. 
  • Prednisone


    The chemical name for a derivative of cortisone used in oral corticosteroid therapy. (See general corticosteroid therapy)
  • Preservatives


    Most cosmetics and topical treatments need protection against microbial contamination, during manufacture as well as during use. This protection is provided by anti-microbial substances known as preservatives. The use of preservatives is strictly regulated (national and European regulation) and all preservatives currently used have an excellent level of efficacy and safety, even if there are rare cases of intolerance by certain individuals. The major preservatives are parabens, alcohols, formalin, triclosan, kathon, Euxyl and other chemical substances.  Certain manufacturing processes and use of sterile environments (sterile cosmetics) facilitate the omission of preservatives.
  • Prevalence

    Number of individuals suffering from a certain disease at a given time in a given population.

  • Prevalence


    The frequency of a condition in a population. 
    The prevalence of atopic dermatitis varies depending on age and country. It is generally between 5 and 15% of the population in infancy, and between 2 and 5% of adults. Higher percentages are seen in certain countries.  
  • Prick-tests


    Allergy tests whereby an allergen is introduced into the epidermis by pricking the skin with a special instrument. Tests by injection, whether using prick-tests or intradermal tests, are used in respiratory allergology. A positive test results in an itchy papule, which appears minutes after administration of the allergen.
  • Probiotics


    Probiotics are bacteria commonly found in the gut and considered to be beneficial for health. They are currently subject to study in various fields, above all in digestive diseases. Digestive bacteria have a role in establishing digestive immunity as well as general immunity. However, probiotic supplements (lactobacilla, bifidobacteria) have no significant effect on the development of atopic dermatitis
  • Prostaglandins


    Lipidic molecules derived from arachidonic acid, which are involved in many of the body's functions, including inflammation
  • Protease


    Enzymes that degrade proteins. There are many proteases, and the consequences of their actions are varied. An excess of proteases has been observed in atopic dermatitis, which is responsible for breaking down certain important proteins for epidermal function, such as filaggrin.  
  • Pruritis

    Pruritis or itching is the main manifestation of atopic eczema. It disrupts sleep and causes scratching lesions.

  • Pruritus


    A synonym of itching. Pruritus is the fundamental symptom of atopic dermatitis, and the primary source of impact on daily life of patients and their families. Pruritus causes excoriation, lichenification (see these terms) and can encourage secondary infection. It can also have impact on mood, sleep, and quality of life in general. In summary, pruritus is the primary element in the condition's burden, and many treatments aim to improve it. Patients learn how to manage pruritus and scratching during therapeutic education
  • Psoriasis

    Is a benign chronic skin disease, characterized by erythematosquamous lesions ...
    Psoriasis is frequent both in men and women ...

  • Psychosomatic


    A term to describe the fact that many conditions have a significant psychological element, which may require specific management. Atopic dermatitis obviously influences the psyche, but this varies from patient to patient. It is common for psychological stress, family, school or professional problems to have an impact on the condition's development. However, indications for psychotherapy are rare. 
  • Psychotherapy


    Treatment by a psychologist. There are two types of psychotherapy: psycho-analysis and the techniques it inspires, and behavioral psychotherapy. 
  • Pulpitis


    Dermatitis localized around the extremities of the fingers and toes, particularly in children. It can manifest as inflammation (for example atopic dermatitis or psoriasis) or infection (like impetigo).
  • Pulpitis


    Inflammation of the flesh on the joints of the fingers and toes. It can be caused simply by irritation, atopic dermatitis or another kind of eczema, or another dermatitis condition. 
  • Purring


    A dermatological term describing a condition in which pruritus is the fundamental symptom. Using this description, it could be said that atopic dermatitis is a prurigo. However this term is currently not commonly used.
  • Pustule


    A skin lesion that consists of a small blister filled with purulent liquid (pus). In atopic dermatitis, pustules indicate secondary infection, generally by staphylococci or streptococci (see impetiginization). It can also indicate herpes (see eczema herpeticum).
  • PUVA


    Photo-therapy technique (see this term) which combines exposure to UVA radiation preceded by taking a photo-sensitizing drug from the family of psoralenes. PUVA therapy is commonly used in treatment for psoriasis