Alopecia: classification according to the cause - Dermatology and aesthetics

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When hair is lost: problems, pathologies, types Alopecia: classification according to the cause Diagnosis Treatment
  • When hair is lost: problems, pathologies, types
  • Alopecia: classification according to the cause
    • Cicatricial alopecia
    • Non-scarring alopecia
  • Diagnosis
  • Treatment

Alopecia: classification according to the cause

There are two scales to measure the degree, level or severity of alopecia (commonly known as baldness), namely the Hamilton and Norwood scales; in the first place, however, the manifestations of alopecia are distinguished in two completely different entities, namely the cicatricial forms (permanent) and the non cicatricial ones (reversible and not).

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Cicatricial alopecia

From a clinical point of view, the destruction of the tissue in the form of atrophy and scarring is evident. Different varieties of cicatricial alopecia are distinguished, and in particular congenital and acquired forms.

Congenital atrichia (autosomal recessive condition that determines the absence of hair follicles in adults), hypotrichosis, associated with other defects in various hereditary syndromes (atrichia with keratin cysts, ectodermal hydrotic dysplasia, progeria, syndrome) of Moynahan, Baraitser syndrome) and moniliform aplasia.

As regards the acquired scarring alopecia, these are distinguished on the basis of the trigger, which can be physical (trauma, X-rays, wounds), chemical (acids, alkalis), biotic (herpes zoster, leprosy, tuberculosis, syphilis secondary and tertiary, fungal infection), dermatological (current or previous dermatosis such as lupus erythematosus, scleroderma, skin tumors, granulomas, sarcoidosis, keloids, Brocq pseudoarea, lichen) or finally psychosomatic (pathomimias, neurotic excoriations).

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Non-scarring alopecia

From a clinical point of view, in these cases there is no evident sign of tissue inflammation, scarring or atrophy of the skin. At the origin of the condition there may be congenital factors, therefore genetic anomalies or developmental defects (physiological alopecia of the newborn baby, congenital atrichia, hypotrichosis associated with various syndromes), or acquired following the action of different elements involved.

We can distinguish alopecia as follows:

  • genetic-hormonal (androgenetic alopecia);
  • hormonal (post-pregnancy or post-hypothyroidism alopecia, hypopituitarism, diabetes, hypoparathyroidism);
  • follicular reaction with hair cycle disorder (telogen effluvium, anagen effluvium);
  • nutritional-metabolic (malnutrition with protein-calorie deficiency, iron or zinc deficiency, deficiency of essential fats, malabsorption syndromes, congenital errors of metabolism);
  • physico-chemical (from trauma or deriving from the use of drugs, chemical agents, X-rays, cosmetic tractions);
  • from drugs (thallium, heparin, dicumarolics, methotrexate, alkaline shampoos, cyclophosphamide, colchicine, thiouracil, vitamin A in high doses and retinoids, propanolol, bromocriptine);
  • idiopathic (alopecia areata or Celsi area, characterized by the presence of one or more patches with the presence of "exclamation point" hair at the edges of an active patch and corpsed hair that take on the appearance of blackheads; chronic diffuse alopecia);
  • infectious (viral or bacterial, for example from syphilis or leprosy, mycotic, for example from Tinea capitis);
  • neoplastic.
  • psychosomatic (emotional stress or trichotillomania, a disorder in which the patient tears his hair creating an alopecic patch on the scalp with hair broken at various heights).

Androgenetic and aerated alopecia deserve a more extensive discussion.

Androgenetic baldness affects about 70% of men after 30 years of age, is hereditary and due to the constitutional sensitivity of the hair follicles to the action of male hormones (testosterone and dihydrotestosterone), therefore it has as a single cause the family predisposition (even if stress, together with an excessive production of sebum and dandruff, can be contributing factors). It begins slowly and progressively, with the backward movement of the hairline at the front level, and can reach various levels of gravity and then stabilize; the wider and deeper the retreat, the more rapid and severe the level of baldness: in particular, slow-evolving forms are distinguished, which generally begin from the age of 28-35, and then gradually increase without reaching consequences worrying, and rapidly evolving forms, which instead occur around 19-20 years, to arrive at a complete evolution already around 30 years. In both cases, a crown of hair back and side to the neck and temples is almost always spared, and this is why for hair transplantation the follicles are taken from the nape (donor area) as they are not subject to baldness, which instead affects the other areas of the head.

Alopecia areata, also known as Celsi area, is also hereditary, specifically caused by a disorder of the immune system. It occurs in young people with round or oval-shaped patches and can extend to the entire scalp. Often it completely regresses in a few months, but in some cases it stabilizes throughout its life or reappears occasionally; the percentage of cases of persistence for life is still very low (1 or 2%), but hair transplantation is the only possible solution.

As can be understood from this summary classification, alopecias are complex pathological entities, at the origin of which complex and sometimes multiple factors contribute which make their treatment difficult.

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