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  • The term comes from "alopex" (renard) because of the annual drop of the hairs of this animal
  • Alopecia is a transient or definitive scarcity or disappearance, localized or diffuse hair


  • Very frequent reason for consultation affects both men and women
  • Affects more often adults, is more severe in children
  • The most common forms are: pelade and androgenic alopecia

Alopecia 1
ical reminder:

  • Normal hair has between 100,000 and 160,000 hairs
  • The average density is 250 to 300 hairs per cm2
  • 30 to 80 hairs are renewed per day, a fall of more than 100 hairs day is pathological
  • A seasonal increase in the fall is noted in autumn
  • Hair follicle: is a thin epidermis envelope that has been dug into the dermis, to house the hair root, 4 mm below the scalp
  • Papille: through which blood arrives
  • Matrix: which generates keratin cells and turns them into hair
  • Epithelial sheaths: which act as guardian to the pilary stem in formation
  • Hair cycle: all hair is born, lives and dies and everything starts again is called the hair cycle

Anagen phase: growth phase, it corresponds to a phase of proliferation of keratin-forming matrix keratin keratins, lasts 3 to 7 years and determines the length of the hair that grows on average 1 cm per month, longer in women

Catagen phase: the involution phase is a phase of regression, it corresponds to the involution of the hair follicles by cell death of the keratinocytes with shortening of the epithelial stem and upward movement of the follicle. This phase is very fleeting and lasts about 15 days

Telengenic phase: resting phase is a profound modification, reactive trichocytes form a new germ structure

Exogenous phase: hair fall phase, enzymatic phenomena release the attachments of the old hair shaft and the telogen hair will detachAlopecia 2

CAT in front of alopecia

Etiological diagnosis:

  • Interrogation: it must identify the following elements: start date, intensity, contributing factors (stress, medication, exposure to a toxic, cosmetic habits…), personal medical-surgical history, family history, treatments and results. These elements will help to evoke:

Telenen Effluvium: Recent, rapid and diffuse fall

Oalopecia constituted: progressive imperceptible

Alopecia linked to a dermatological condition

Alopecia linked to a general condition: hormonal, infectious…

  • Clinical review:

Physics: first skin-mucous or ungueal impairments, signs of nutritional deficits (martial deficiency or trace elements), clinical signs of general pathology (dysthyroidism, hirsutism, acne, cycle disorders)

Examination of alopecia areas: location of alopecia areas

Appearance of the scalp: healthy, squaby, pustlay, inflammatory or scarred

Alopecia 3 Appearance of hair: hair dysplasia (hereditary alopecia), broken hair (trichotillomania), traction resistance, presence of small hair, down hair, brittle hair

Importance of Falling: Traction Test

  • Additional examinations: they are rarely necessary and are necessarily guided by interrogation and the clinic.


Trichogram: 50 hairs are plucked with pliers, it is made in three zones (frontal, vertex and low occipital), then the roots are examined under a microscope. This examination confirms the absence of hair dystrophy, it helps to reassure the patient when the hair fall is physiological. It helps to clarify the mechanism of the fall (anagen effluvium or telogen effluvium), allows to calculate the ratio of telogens to anagens (increased during evolutionary outbreaks of androgenic alopecia (AAG))

Mycological Review (Wood Light)

Bacteriological Examination

Examination of hair in polarized light optical microscopy: highlights hair dysplasia

Skin biopsy direct immunofluorescence: scar or tumor alopecia

Biological balances: NFS (deficiency…), dosage of trace elements (zinc, suffers…), hormonal dosages: thyroid (TSH, T3, T4), testosterone, DHEA, progesterone (in search of adrenal hyperandrogenism), androsenidion D4 (research ovarian hyperandrogenism), liver and renal balance (looking for deficiencies)

Main types of alopecia:

  • Diffuse alopecia:

Telenen Effluvium:

Definition: diffuse scarcity of hair, healthy scalp, positive traction test,

acute or subacute phenomenon, predominates in the temples and near the ears

Triggers (2-3 months): childbirth, abortion, prolonged fever (infectious or otherwise), acute hemorrhage, sudden weight loss, stress, emotional shock…

Evolution: spontaneous regrowth in 4 to 6 months or even a year

Driving to be held: reassure the patient, ask for a biological check-up if the fall is very large or persistent, twice-daily applications for 2 to 3 months of Minoxidil 2% or 5% with risk of increased effluvium at the start of treatment

Alopecia 4Iatrogenic alopecia:

Toxic: pesticides, arsenic…

Drug ▪: antimitotics

Alopecias linked to a general pathology: dysthyroidism, systemic diseases with type of connectivity, lymphomas, vascularities…

Infectious Alopecias: parasitic (malaria), viral (zona), bacterial…

Androgenetic alopecia: the terms androgenetic alopecia explains the double origin of this phenomenon: the receptivity to male hormones of the hair roots, the genetic predestination of the hair to undergo this stimulation

epidemiology ▪:

Men: they reach one in three to 30-year-olds almost one in two to 50 years of age

Women: about 70% of women have to deal with a hair loss problem during a period of their lives but they are generally hormonally favoured until menopause or premenopause

Alopecia 5▪ Di-Hydro-Testosterone (DHT) in the pilo-sebaceous follicle induces a reduction in the anagen phase, an inhibition of growth and involution of the dermal papilla, a miniaturization of the pilo-sebaceous hair follicle. DHT has the opposite effect: on the hair growth / on the hair evolution

▪ The image of alopecia as Hamilton and more recently Norwood classified it, where occipital area maintenance is observed

▪ The image of androgenetic alopecia defined by Ludwig in three stages (I, II, III) or the maintenance of frankness will be noted

Alopecia 6 In male subjects: there is first a temporo-parietal recoil forming gulfs, then a frontal decay and occipito-vertical tonsure. The affected areas first keep some intermediate hair and downs, which can then disappear completely. Hamilton and then Norwood defined the evolutionary stages usually followed by baldness in humans

Alopecia 7 In female subjects: anteroposterior evolution is less marked than in men. Alopecia is more diffuse and draws a cap that respects a narrow frontal anterior headband, as well as the temporal and occipital regions. Intermediate hair and downs remain mixed with many terminal hair. Ludwig described three grades of increasing severity, between which there are no objective limits

▪ Search for biological hyperandrogenism in front of androgenetic alopecia:

Unnecessary in humans

Unnecessary in a well-regulated woman with no acne or hirsutism

Unnecessary if small signs of hyperandrogenism in perimenopause

Between the third and sixth day of the cycle, away from any hormonal intake

In resource: testosterone, delta-4-androstenedione

Suspicion of adrenal origin: immediate Synactent test (17-OH-P and 21 deoxy-cortisol)

Suspicion of ovarian origin: ultrasound (trans-vaginal), prolactin, FSH, LH

Driving to be held:

Minoxidil 2% or 5%, 2 applications/day for months.

Male: Finasteride (5-reductase inhibitor): 1 mg/d for 2 years.


Anti-androgen treatment: cyprorotone acetate (Androcur): 25-

50 mg/day, from the 1st to the 21st day of the cycle (hirsutism)

Oestroprogestative: Day 1-21: Diane 35

Surgical treatments: reserved for patients whose baldness has stabilized

Autografts: mini- and micro-graft

  • Alopecia 8Localized alopecia:


Pelade: it affects 2% of the population, of unknown etiology, genetic predisposition, environmental factors, infectious factors, emotional stress, neurological factors (association with vitiligo, thyroiditis…), it occurs in a subject generally in good condition and on a healthy scalp.

Alopecia in isolated or multiple plates, can become widespread (decalding pelade) or even reach all hair areas (universalis pelade).

Ungueal attainment is possible (micro-abrasions, longitudinal streaks)

Evolution: is unpredictable: healthy regrowth in several months (white down that pigments later), extension, recurrence

Driving to be held:

Limited forms: local application of corticosteroids in injection, local application of Minoxidil 2% or 5%

Diffuse forms: intra-lesionic-injection corticosteroids, dermocorticoids, general corticosteroids in bolus (recent extensive pelade), contact immunotherapy (PUVAtherapy), Methotrexate – corticosteroids: 25 mg/week, 9 to 18 months.

In some cases (diffuse or recurrent forms): psychological management is necessary

Alopecia 9 Infectious Alpecies:


Impetigo and folliculitis: pustusous scalp, inflammatory, tufted hair, satellite lesions, bacterial sampling, antibiotic treatment


▪ They are clinically characterized by: atrophy of the scalp, a disappearance of pores corresponding to the destroyed follicles.

▪ They are the result of an inflammatory state where the hair follicle is either the direct target (hair plan lichen, skin lupus, decalvading folliculitis…) or destroyed in a non-specific way (sarcoidosis, scleroderma, trauma…)

▪ Destruction by an inflammatory infiltrat of the infundibular region where stem cells are located capable of regenerating a damaged follicle

Alopecia 10 Traction Alopecia: Unlike the female AAG, traction alopecia gladly reaches the temples and the front anterior edge. In the progression areas, there are short broken hair, not downs. The hairs in bun very pulled back, the braids knotted tight, after the straightening of the frizzy hair, the natural hair can, by continuous traction, result in the destruction of certain follicles

Lichen follicular plan: middle-aged woman, numerous coalescent expansive atrophic plaques, purplish perefollicular erythema, follicular hyperkeratosis. Rarely associated skin or mucous lichen (17-28%)

Post-menopausal frontal fibroid alopecia (Pinkus fibroid alopecia): a very particular clinical form of follicular lichen plane, described only in postmenopausal women. Frontal and temples, symmetrical and bandeau, erythema and follicular hyperkeratosis at the edge during periods of activity

Congenital Alopecias: skin atrophy, scarred scalp

▪ Etiological treatment, where possible and effective, can stop the progression of alopecia, which, if it forms and becomes scarring, is only surgery


  • Alopecia is a common reason for consultation, Etiologies are numerous: hormonal, nutritional, infectious, medicinal, etc.
  • Androgenic alopecia and pelade remain the most common
  • Physiological lyegenic effluvium, a clinical diagnosis, often requires no explorationors or treatments.
  • In children, a mycological examination should be systematic.
  • Explorations are not systematic.
  • The treatments, many, are more or less effective.

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