MedicineNet


Melasma Glossary of Terms

The following are health and medical definitions of terms that appear in the Melasma article.

Aging: The process of becoming older, a process that is genetically determined and environmentally modulated.
See the entire definition of Aging

Aluminum: A naturally occurring element that makes up about 8% of the surface of the earth and is always found combined with other elements such as oxygen, silicon, and fluorine. Aluminum is is the most common metallic element in the earth's crust but has no clear biologic role. Everyone is exposed to low levels of aluminum from food, air, and water. Exposure to high levels of aluminum may result in respiratory problems (aluminosis). Inhalation of bauxite (aluminum ore) fumes may cause pulmonary fibrosis. Aluminum in the bloodstream may lead to neurological symptoms and may be fatal.
See the entire definition of Aluminum

Biopsy: The removal of a sample of tissue for purposes of diagnosis. (Many definitions of "biopsy" stipulate that the sample of tissue is removed for examination under a microscope. This may or may not be the case. The diagnosis may be achieved by other means such as by analysis of chromosomes or genes.)
See the entire definition of Biopsy

Birth control: Birth control is the use of any practices, methods, or devices to prevent pregnancy from occurring in a sexually active woman. Also referred to as family planning, pregnancy prevention, fertility control, or contraception; birth control methods are designed either to prevent fertilization of an egg or implantation of a fertilized egg in the uterus.
See the entire definition of Birth control

Breastfeeding: Feeding a child human breast milk. According to the American Academy of Pediatrics, human breast milk is preferred for all infants. This includes even premature and sick babies, with rare exceptions. It is the food least likely to cause allergic reactions; it is inexpensive; it is readily available at any hour of the day or night; babies accept the taste readily; and the antibodies in breast milk can help a baby resist infections.
See the entire definition of Breastfeeding

Chin: Medically, the mentum. The lower portion of the face below the lower lip including the prominence of the lower jaw and the line of fusion of the two separate halves of the jawbone (mandible). This line of fusion (called the symphysis menti) encloses a triangular area at tip of the chin (termed the mental protuberance). On each side, below the second premolar tooth, is the mental foramen, an opening for the passage of blood vessels and a nerve that supply the chin.

Chronic: This important term in medicine comes from the Greek chronos, time and means lasting a long time.
See the entire definition of Chronic

Dermal: Pertaining to the skin. From the Greek word derma for skin.

Dermis: The lower or inner layer of the two main layers of cells that make up the skin.The dermis contains blood vessels, lymph vessels, hair follicles, and glands that produce sweat, which helps regulate body temperature, and sebum, an oily substance that helps keep the skin from drying out. Sweat and sebum reach the skin's surface through tiny openings in the skin that act as pores.

Dopamine: An important neurotransmitter (messenger) in the brain.
See the entire definition of Dopamine

Dry skin: Abnormally dry skin. Can be caused by a dry climate, winter weather, deficiency of vitamin A, systemic illness, overexposure to sunlight, or medication. The skin loses moisture. It may crack and peel. Or it may become irritated, inflamed, and itch. Bathing frequently, especially with soaps, can contribute to dry skin.
See the entire definition of Dry skin

Enzyme: A protein (or protein-based molecule) that speeds up a chemical reaction in a living organism. An enzyme acts as catalyst for specific chemical reactions, converting a specific set of reactants (called substrates) into specific products. Without enzymes, life as we know it would not exist.
See the entire definition of Enzyme

Epidermal: Pertaining to the epidermis, the outermost layer of the skin.

Epidermis: The upper or outer layer of the two main layers of cells that make up the skin. The epidermis is mostly made up of flat, scale-like cells called squamous cells. Under the squamous cells are round cells called basal cells. The deepest part of the epidermis also contains melanocytes. These cells produce melanin, which gives the skin its color.
See the entire definition of Epidermis

Erythema: A redness of the skin resulting from inflammation, for example, as caused by sunburn.

back to top

Estrogen: Estrogen is a female hormone produced by the ovaries. Estrogen deficiency can lead to osteoporosis.
See the entire definition of Estrogen

Exfoliate: 1) To peal off scaly skin spontaneously. The skin exfoliates from the palms and soles in Kawasaki's disease and Reiter's syndrome. 2) To deliberately wear away the top layer of skin, as many be done gently by a facial technologist who is applying a topical skin treatment for cosmetic purposes, or more severely by a dermatologist treating acne. In the latter case, the most common exfoliating methods are sanding and chemical peels.

Family history: The family structure and relationships within the family, including information about diseases in family members.
See the entire definition of Family history

Fetus: The unborn offspring from the end of the 8th week after conception (when the major structures have formed) until birth. Up until the eighth week, the developing offspring is called an embryo.

Genetic: Having to do with genes and genetic information.

Hormone: A chemical substance produced in the body that controls and regulates the activity of certain cells or organs.
See the entire definition of Hormone

Hormone therapy: A form of treatment that takes advantage of the fact that certain cancers depend on hormones to grow. Hormone therapy may include giving hormones to the patient or decreasing the level of hormones in the body.

Hyperpigmentation: Dark spots on the skin. Hyperpigmentation is primarily a cosmetic concern that can be covered with make-up, although in some cases (such as the cafe au lait spots associated with neurofibromatosis) it can be a sign of an underlying medical problem. If treatment of hyperpigmentation is desired, a dermatologist may be able to use dermabrasion, laser treatments, or bleaching agents to effect change.

Itching: An uncomfortable sensation in the skin that feels as if something is crawling on the skin or in the skin, and makes the person want to scratch the affected area.
See the entire definition of Itching

Jaw: The bones below the mouth (the mandible) and the bone above the mouth just above the mouth (the maxilla). The word jaw comes from the Anglo-Saxon ceowan meaning to chew.

Jawbone: 1. As a noun, a bone of the jaw, particularly the mandible.
2. As a verb, to try and influence with words (jawbones) rather than force.

Laser: A powerful beam of light that can produce intense heat when focused at close range. Lasers are used in medicine in microsurgery, cauterization, for diagnostic purposes, etc. For example, lasers are employed in microsurgery to cut tissue and remove tissue.
See the entire definition of Laser

Lightening: Not to be confused with a discharge of atmospheric electricity, lightening refers to the sensation that a pregnant woman feels when the baby drops. This is the time when the presenting (lowermost) part of the fetus descends into the maternal pelvis.
See the entire definition of Lightening

Malar: Referring to the cheek.

Melanin: A skin pigment (substance that gives the skin its color). Dark-skinned people have more melanin than light- skinned people. Melanin also acts as a sunscreen and protects the skin from ultraviolet light.
See the entire definition of Melanin back to top

Melasma: Pigmentation of the face, most commonly on the malar area (the upper cheek), bridge of nose, forehead, and upper lip, that occurs in half of women during pregnancy. Birth control pills can also cause melasma. However, hormone therapy after menopause does not cause the condition.
See the entire definition of Melasma

Neck: The part of the body joining the head to the shoulders. Also, any narrow or constricted part of a bone or organ that joins its parts as, for example, the neck of the femur bone.

Nose: The external midline projection from the face.
See the entire definition of Nose

Ochronosis: 1. Deposition of dark pigment in connective tissues, usually due to alkaptonuria or exposure to chemicals such as phenolic compounds or hydroquinone.
2. Sometimes used as a synonym for alkaptonuria.

Onset: In medicine, the first appearance of the signs or symptoms of an illness as, for example, the onset of rheumatoid arthritis. There is always an onset to a disease but never to the return to good health. The default setting is good health.
See the entire definition of Onset

Pigment: A substance that gives color to tissue. Pigments are responsible for the color of skin, eyes, and hair.

Pigmentation: The coloring of the skin, hair, mucous membranes, and retina of the eye.
See the entire definition of Pigmentation

Postmenopausal: After the menopause. Postmenopausal is defined formally as the time after which a woman has experienced twelve (12) consecutive months of amenorrhea (lack of menstruation) without a period.
See the entire definition of Postmenopausal

Pregnancy: The state of carrying a developing embryo or fetus within the female body. This condition can be indicated by positive results on an over-the-counter urine test, and confirmed through a blood test, ultrasound, detection of fetal heartbeat, or an X-ray. Pregnancy lasts for about nine months, measured from the date of the woman's last menstrual period (LMP). It is conventionally divided into three trimesters, each roughly three months long.
See the entire definition of Pregnancy

Pregnant: The state of carrying a developing fetus within the body.
See the entire definition of Pregnant

Prescription: A physician's order for the preparation and administration of a drug or device for a patient. A prescription has several parts. They include the superscription or heading with the symbol "R" or "Rx", which stands for the word recipe (meaning, in Latin, to take); the inscription, which contains the names and quantities of the ingredients; the subscription or directions for compounding the drug; and the signature which is often preceded by the sign "s" standing for signa (Latin for mark), giving the directions to be marked on the container.

Progesterone: A female hormone and the principal progestational hormone that is made mainly by the corpus luteum in the ovary and by the placenta. Progesterone prepares the lining (endometrium) of the uterus (the womb) to receive and sustain the fertilized egg and so permits pregnancy. Similarly refers to synthetic versions of the hormone. Also known as progestational hormone.

Prognosis: 1. The expected course of a disease.
2. The patient's chance of recovery.
The prognosis predicts the outcome of a disease and therefore the future for the patient. His prognosis is grim, for example, while hers is good.
See the entire definition of Prognosis

Pruritus: Itching. Pruritus can result from drug reaction, food allergy, kidney or liver disease, cancers, parasites, aging or dry skin, contact skin reaction, such as poison ivy, and for unknown reasons.

Quality of life: An important consideration in medical care, quality of life refers to the patient's ability to enjoy normal life activities. Some medical treatments can seriously impair quality of life without providing appreciable benefit, while others greatly enhance quality of life.

back to top

Retinoid: 1. Vitamin A (retinol) or a naturally occurring or synthetic substance chemically related to it. (Retinoid literally means "like retinol.")
2. In ophthalmology, resembling the retina.

Scaling: Abnormal shedding or accumulation of an upper layer of skin (the stratum corneum).

Sensation: In medicine and physiology, sensation refers to the registration of an incoming (afferent) nerve impulse in that part of the brain called the sensorium, which is capable of such perception. Therefore, the awareness of a stimulus as a result of its perception by sensory receptors. (Sensory is here synonymous with sensation.)
See the entire definition of Sensation

Sensitivity: 1. In psychology, the quality of being sensitive. As, for example, sensitivity training, training in small groups to develop a sensitive awareness and understanding of oneself and of ones relationships with others. 2. In disease epidemiology, the ability of a system to detect epidemics and other changes in disease occurrence. 3. In screening for a disease, the proportion of persons with the disease who are correctly identified by a screening test. 4. In the definition of a disease, the proportion of persons with the disease who are correctly identified by defined criteria.

Skin biopsy: Removal of a piece of skin for the purpose of further examination in the laboratory using a microscope.


See the entire definition of Skin biopsy

SPF (sun protection factor): A number on a scale for rating the degree of protection provided by sunscreens. SPF stands for Sun Protection Factor.
See the entire definition of SPF

Steroid: A general class of chemical substances that are structurally related to one another and share the same chemical skeleton (a tetracyclic cyclopenta[a]phenanthrene skeleton).
See the entire definition of Steroid

Sunscreen: A substance that blocks the effect of the sun's harmful rays. Using lotions that contain sunscreens can reduce the risk of skin cancer, including melanoma.

Superficial: In anatomy, on the surface or shallow. As opposed to deep. The skin is superficial to the muscles. The cornea is on the superficial surface of the eye.
See the entire definition of Superficial

Therapy: The treatment of disease.
See the entire definition of Therapy

Topical: Pertaining to a particular surface area. A topical agent is applied to a certain area of the skin and is intended to affect only the area to which it is applied. Whether its effects are indeed limited to that area depends upon whether the agent stays where it is put or is absorbed into the blood stream.

Zinc: A mineral essential to the body, zinc is a constituent of many enzymes that permit chemical reactions to proceed at normal rates. It is involved in the manufacture of protein (protein synthesis) and in cell division. Zinc is also a constituent of insulin, and is concerned with the sense of smell.
See the entire definition of Zinc

Zinc oxide: A form of zinc that has antispasmodic qualities.

back to top