Actinic keratoses

Precursors of squamous cell carcinomas. They present as a rough, localized thickening of skin's surface. Some go on to develop into a carcinoma.

Actinic lentigo or lentigines

Small, flat, irregularly-shaped pigment spots often found on the top of the shoulders following sunburn or repeated UV exposure.


Basal cell carcinoma

Refers to cancers affecting the basal cells of the epidermis. It is the commonest form of skin cancer.


Sample of suspect tissue sent for histological analysis.



A disease characterised by abnormal cell proliferation within a normal body tissue. Over the course of the disease's development, the resulting mass of new cells can form a malignant tumor or travel throughout the body, forming metastases.

Connective tissue

Tissue composed of fibers that surrounds and protects organs.


Liquid nitrogen application to destroy skin lesions.



Skin layer situated just beneath the epidermis. The dermis is rich in fine blood vessels, as well as collagen and elastic fibers, which ensure skin's resistance and elasticity.


Skin examination technique using a specific optical tool (surface skin microscopy), useful for a more precise diagnosis of pigmented lesions.





Skin's most superficial layer, essentially made up of keratinocytes, responsible for manufacturing keratin. The most superficial part is the corneal layer.


The surgical removal of a skin tumor.



Skin aging, often premature, caused by chronic and/or prolonged sun exposure.


Deepest skin layer, situated beneath the dermis. This layer of skin is rich in fat and blood vessels and its role is to dampen pressure applied to the skin and protect the body from temperature fluctuations.



The principal component of skin, hair, body hair, nails and dental enamel in humans. It is a highly resistant, water insoluble, fibrous protein, which ensures skin's impermeability and external protection.


Cells making up 90% of skin's superficial layer (epidermis) and integuments (nails, hair, body hair). They synthesize keratin (keratinization).



Auto-immune disease. It can reach numerous organs, by the development of auto-antibodies (antibodies produced by the organism against himself) against core and AND cells.



Dark-colored pigment responsible for skin and hair color. Melanin is found in the epidermis, where it is synthesized by melanocytes. Melanin's role is to help protect skin from the harmful effects of ultraviolet rays.


Cells responsible for the manufacture of melanin. They are found in the basal layer of the epidermis.


A cancer affecting melanocytes, the cells responsible for manufacturing melanin. It is the most serious form of skin cancer. It can prove fatal if not diagnosed early. It can metastasize and migrate to other organs such as the liver, lungs, bones and brain. It has become increasingly common over the past 50 years and its incidence doubles every 10 years.


Growth of a pathogenic organism or tumor cell at a different location from the originally affected site. In humans, metastases can occur through the distribution of malignant cells or micro-organisms in the bloodstream (=hematogenic) or the lymphatic system (metastatic lymphatic ganglions).



More commonly referred to as a "mole", a nevus is a lesion caused by a clustering together of melanocytes. Nevi may be present at birth, but generally appear during childhood and develop over the years.



Skin condition arising after sun exposure due to abnormally high sensitivity to UV light.

Photo-sensitizing substances

Many plants produce powerful chromophores. The most potent molecules are part of psoralene or furocoumarin groups. They are mainly encountered in plants belonging to:

  • Rutaceae: bergamot orange, lime, bitter orange, fig.
  • Umbelliferae: parsley, chervil, celery, fennel, angelica.
  • Flowers: buttercup, geranium, St. John's wort.
Topic medication
  • They are responsible for many photosensitizing reactions.
  • Antihistamine (ex: Promethazin in cream) and anti-inflammatories (ex: ketoprofen) often causes intolerance reactions due to contact allergy or photoallergy.
  • Anti-acneic (ex: Benzoyl peroxide, Tretinoin) as well as certain colouring agents (eosin, fluorescein) lead to a light photosensitization.
  • Musk ambrette (fixative of perfume).
  • Balsam of Peru.
UV filters
  • Benzophenones, Oxybenzones, Cinnamates.
  • They are often at the origin of photosensitizations and traditionally of plant origin. Today, principally synthetic but of an identical chemical structure as regards the odorous molecules responsible for photosensitizations.
  • It concerns principally the bergamote, very photo-toxic, and other essential oils: lavender, sandalwood, cedar, and vanilla.
Oral medication
According to the molecule and the dose, photo-sensitizing power is variable. There are different aspects of reactions on the skin according to medicaments.
List of medicaments, beauty products, perfumes and vegetables photosensitizing:
  • Antibiotics: Cyclines, Quinolones, Sulfonamides, Ceftazidine, Isoniazid.
  • Psychotropic: Phenothiazines, Benzodiazepines, alprazolam, Carbamazepine, Imipraminiques.
  • Normolipemiants: Fibrates.
  • Non-steroidal anti-inflammatory: Piroxicam, Ketoprofen, Diclofenac.
  • Quinines and stemming, Amiodarone, Psoralenes, Flutamide, Inhibitors of the enzyme of conversion, Nifedipine, Ribavirine, Pyridoxine.

Photo-toxic reactions

An abnormally strong skin reaction to sun exposure associated with the use of medication.


Classification of individuals according to their skin's response to sun exposure.

PPD (Persistent pigment darkening)

Measures skin's response to exposure to UVA only. It evaluates the degree of anti-UVA protection provided by the immediate, visible skin pigmentation induced by a given dosage of rays.


Solar erythema (sunburn)

Skin redness (inflammatory reaction) following sun exposure.

SPF (Sun protection factor)

Number indicating sun protection. It is used to give a value to the degree of protection provided by sun creams. It is a measure of the time required for skin to develop solar erythema.

Squamous cell carcinoma

Cancer of the epidermal keratinocytes.


Topical treatment

A treatment applied locally, directly onto lesions affecting the skin or scalp.


A proliferation of new cells constituting a pathological (diseased) tissue. It results from these cells' abnormal activity, which ensues for no apparent reason, with the cells tending to persist or increase in volume. This cell proliferation leads to an increase in the volume of an organ or part of an organ. A tumor can be benign or malignant depending on the type of cells forming it.



A for Aging. UVA rays cause skin aging. They make up 90% of the UV rays reaching skin. UVA are present all year round, at all latitudes; they are capable of passing through both clouds and panes of glass. They reach the dermis and damage cutaneous structures deep down. They are the main cause of premature skin aging: wrinkles, brown spots, loss of elasticity, dryness… The role they play in the development of skin cancers has also recently been demonstrated.


B for Burn. UVB cause sunburn and affect the epidermis. They stimulate melanin production, and thus tanning, but also cause sunburn and damage the DNA of skin cells. They have a firmly established role in the development of skin cancers.


Extremely harmful UV rays, but entirely filtered out by the atmosphere, never reaching the earth's surface. They have a short wavelength.