Medical Dictionary

Welcome to the medical dictionary dedicated to trichology

A - C

Abbreviation of androgenetic alopecia.

Partial or total loss of hair in areas where it is normally present.

Characterised by the appearance of one or more hair-free patches (especially in the beard area) without skin disorders except occasionally a slight and reversible epidermal atrophy. These alopecic areas can spontaneously thicken or extend to the entire scalp and/or all body hair (universal alopecia). Small, short and broken dystrophic anagen hairs are found around the edge of the patches, characteristically thinner in the vicinity of the bulb (exclamation point hairs) and pathognomonic for this pathology. Considered to be a stress pathology, it actually has very complex origins, also linked to immunological factors.

The phase of active hair growth with a variable duration from 2 to 5 years.

Regulated by androgens. It may mean both a physiological hormonal stimulus and a defect due to impaired androgen function.

The most frequent form of non-scarring alopecia. It is characterised by hair loss in the vertex area and by frontal/temporal receding not affecting the nape area and temples.

Male hormones responsible for regulating the function of the sexual organs and the development of secondary sexual characteristics. They are produced partly by the testicles and partly by the adrenal glands.

Reduced development and function of an organ

More or less complete and definitive absence of hair.

Transition phase following the anagen phase, lasting approximately two – three weeks. It corresponds to the hair involution phase that precedes the physiological loss.

A scale that describes the stages of progression of hair loss in men

This filamentous protein produced by keratinocytes is the main constituent of the superficial skin layer (stratum corneum) and essential constituent of the skin appendages: hair on the body and head, nails.

A scale that describes the stages of progression of hair loss in women

This causes the formation of hair-free areas and sebaceous glands. This phenomenon is irreversible. Scarring alopecia can sometimes be the first symptom of other skin conditions (lupus, lichen etc.)

D - F

Due to an accelerated replacement of epidermal cells. It is made up of a cluster of horny cells that take on the appearance of white or greyish scales distributed throughout the scalp. There is little or no itching. Clinically, it can be divided up into dry or simple dandruff, in which the scalp is healthy, covered by small scales that detach easily, falling onto clothes, with no or modest itching, and greasy or steatoid dandruff, often itchy, in which the scales are larger, greasy and yellowish and they adhere to a scalp that is sometimes slightly erythematous.

Abnormal hair loss in terms of quality rather than quantity leading to hypotrichia or baldness

Common inflammatory diseases of the skin and scalp

Chronic inflammatory skin diseases which, in the scalp, can lead to permanent hair loss.

Abbreviation of dihydrotestosterone

Active metabolite of testosterone produced at follicular level by the 5-alpha reductase type 2 enzyme, responsible for the progressive miniaturisation of the hair.

Quantitatively significant and homogeneous total hair loss in the Telogen phase or in the Dystrophic Anagen phase with spontaneous resolution.

Science that studies the formation and development of the embryo and its organs. Hair follicles are already present at birth and no other follicles will develop over the course of a lifetime.

A potent 5 alpha-reductase type 2 inhibitor. This enzyme present in the hair follicle is responsible for converting testosterone into dihydrotestosterone.

A particular structure of the skin that is found in the dermis from which the hair originates, and is made up of said hair and its sheaths. The excretory duct of a sebaceous gland also opens into the hair follicle, creating the pilosebaceous unit.

Inflammatory dermatitis of the scalp, face and chest, typically itchy and flaking. Seborrhoeic dermatitis of the scalp can present in 2 clinical forms: dry pityriasis and steatoid pityriasis.
Dry pityriasis or dandruff: characterised by small whitish scales. Clinical manifestations, often itchy, can spread to large areas of the scalp.
Steatoid pityriasis: characterised by erythematous patches with indefinite edges, covered by yellowish greasy-looking scales, they are generally not itchy and are typically found on the scalp and on the skin of the midsternal and retroauricular region.
Seborrhoeic dermatitis is frequently associated with androgenetic alopecia, resulting in chronic inflammation of the scalp which can contribute to the aggravation of androgenetic alopecia. Recent studies actually indicate that inflammatory mediators, such as interleukin 1, have a negative effect on follicle growth and induce the arrival of the telogen phase. Inflammation can thus accelerate the miniaturisation process and thus aggravate the disease. Inflammation can also promote fibrosis which is sometimes seen in histological preparations of androgenetic alopecia.

G - L

Science that studies the generation of living beings and the transmission of hereditary characteristics.

Thyroid disorder that can lead to widespread hair loss in the telogen phase as it inhibits cell division in the epidermis and skin appendages (hair on the body and head, nails).

Rare, congenital condition in which the hair on the body and hair is present but is sparse and very thin. No treatment is available.

Liquid solution for topical use, to be applied in the affected areas to obtain the absorption of the active ingredients

M - O

A source of growth factors that support the growth of various tissues. Numerous studies have shown that stem cells with growth factor receptors are also present in the hair bulb. It was therefore decided to use it to stimulate these stem cells. It is obtained by concentrating the autologous platelets (i.e. from the patients themselves) and deriving the platelet growth factors from them (PDGF: Platelet Derived Growth Factors).

Pigment responsible for hair and skin colour.

Antihypertensive vasodilator used orally in clinical practice since the 1980s to treat refractory hypertension. Its side effects included its ability to cause hirsutism. This very side effect was exploited to prepare lotions that can be used to treat alopecia. It has a stimulating effect on the non-atrophic germinal centres. The effect begins to show after at least four months and prolonged treatment is required.

P - S

Colour-producing substance produced by the body which determines the colour of the hair and skin.

Oily substance secreted by the sebaceous glands and excreted, through the pilosebaceous ducts, onto the skin.

T - Z

Corresponds to the resting phase of the hair’s life cycle. It lasts about three months, and ends with the beginning of a new anagen phase and the production of a new hair that pushes out the old hair that is still attached as it grows.

Used to refer to a medicine that is applied directly to the affected site.

The surgery through which healthy, living bulbs are transferred from a donor area (usually the nape) to a recipient area represented by bald or thinning areas.

Trichological science whose aim is to treat hair and skin diseases.

Diagnostic procedure using a microscope to evaluate the relationship between hair in the anagen and telogen phases.

Science that studies the anatomy and pathophysiology of the hair on the body and head.

The set of conditions that enable a cell or a tissue to achieve the ideal nutritional conditions for growth and regeneration.

By vellus hair we mean thin, short, poorly pigmented hair that does not tend to grow. It may indicate ongoing miniaturisation that will lead to definitive hair loss.

Vitamins are biological substances essential for health and correct cell functioning that are not synthesised by the human body but must be introduced with food. Vitamins are divided into fat-soluble vitamins (A, D, E, K), and water-soluble vitamins (C, B12, B-group).


When hair loss exceeds 100/120 units per day and the phenomenon lasts for more than 4 consecutive weeks and/or in the presence of even slight thinning where some areas of the scalp are visible.

Here’s how they differ:
Physiological hair loss: Hairs are living elements that follow three phases: a growth phase called anagen, a regression phase called catagen and finally a rest period called telogen, and it is at the end of this phase that the hair is shed to leave room for the new hair. Losing up to a maximum of 100 hairs per day is to be considered normal (physiological). In two periods of the year, spring and autumn, hair loss increases. Scientists link this phenomenon to the length of the days and the variation in temperature.
Reactive hair loss: this is due to a temporary imbalance in the life cycle of the hair with causes that could be both internal and external (stress, hormonal imbalances, menopause, post pregnancy, poor diet, etc.).
Androgenetic alopecia: commonly referred to as baldness, this is genetic in origin and is due to a hypersensitivity of the hair bulb to the male hormone. The cause of it all is an enzyme called 5-alpha reductase which transforms testosterone into dihydrotestosterone (DHT), which is toxic to the hair follicle.

During a trichological examination, the specialist will be able to evaluate any anomalies of the hair and scalp and subsequently understand the underlying causes of the hair loss. Many disorders could be prevented through early diagnosis.

Absolutely not. The first trichological examination can be carried out at least once a year as a preventative measure and/or to maintain healthy hair.

You can undergo a trichological examination at any age.

The difference between the two techniques lies in the first part of the transplant, namely the way the follicular units are extracted.
FUT TRANSPLANT: a thin strip of skin is taken from the donor area of the scalp, from which the mono- and pluribulbar grafts will be obtained, ready to be transferred to the area in which more hair is required. The linear scar will be imperceptible.
FUE TRANSPLANT: individual follicular units are taken from the donor area using a micro scalpel called a punch, and then transferred to the area in which more hair is required, without any visible linear scar.

Yes, the Hair Implant System.

The Hair Implant System is a surgical solution for baldness with biocompatible hair, aesthetically identical to natural hair, available in lengths from 15 to 45 cm, straight, wavy and curly. It is painless and the return to everyday life is immediate.

Yes. Prosthetic systems and wigs.

The trichological prosthetic system is the solution to baldness with a non-surgical method. The Tricomedit medical centre has three state-of-the-art prosthetic systems. They can be used for all forms of alopecia areata – total, universal and scarring – and also for all those who do not want or cannot undergo surgery.
Unlike prosthetic systems, wigs also cover any existing hair, without damaging it. They are an excellent temporary solution, for anyone undergoing chemotherapy or for those who often want to change their look, both in cases of alopecia areata – total, universal and scarring – and with no hair loss. The products are high quality with a natural effect.

Tricopigmentation is a technique based on the micro pigmentation of the scalp.

Tricopigmentation is not a tattoo, but dermopigmentation of the scalp. It is carried out using different tools and a different protocol.

With permanent tricopigmentation, the pigments used are not resorbable, while with the reversible option they are.

Absolutely not.

About two hours.

When the diet you follow is not correct and after an appointment with a specialist finds a deficiency or lack of minerals and vitamins leading not only to an imbalance at general body level but also hair loss and thinning.

Contrary to what is commonly thought, recent studies have shown that the average number of hairs per square centimetre is almost 10% lower for women than for men (279/312).
As a result, the male hair structure is on average thinner than the female one, as each hair needs less space to develop.

The word hyperseborrhoea derives from the Latin sebum (fat) and from the Greek ρειν (to flow), indicating an anomalous flow of sebaceous material. The term refers to an increase in the activity of the sebaceous glands, hence the excessive production of sebum. Overabundant sebum production occurs mostly on the skin of the scalp. In normal conditions, the sebum has the function of protecting the skin from dehydration and also has an antibacterial effect, but if it is produced in excess, it can give rise to problems such as greasy hair, itching and hair loss.

Scalp pain is a common problem affecting approximately 20% of women and 9% of men and can occur in conjunction with increased hair loss. This could be caused by small inflammations that sometimes accompany androgenetic alopecia or chronic telogen effluvium.

The external surface of the hair is actually covered with very small overlapping flakes, arranged in a regular manner, like the tiles of a roof. These are known as cuticles. The number of layers of the cuticles decreases from the roots towards the ends. This is why the ends are very delicate and less resistant.
If the cuticle, the external part of the hair, is intact, the hair appears shiny and healthy, while if the cuticles are raised, the hair appears dull and lacklustre due to being dry and brittle