Hair Loss: Alopecia Areata
Alopecia areata is a fairly common disturbance of hair growth described by Celsus 2,000 years ago and hence also named after him. “Pelade” is a later dog Latin term originally denoting loss of hair in general, whatever its origin or type.
Incidence. Alopecia areata is diagnosed in 2—3% of new dermatological patients of all ages and has even been found in infants and toddlers. In about 38% of all new cases the first signs appear before the age of 20. Alopecia areata occurs in people of every race, with a mild prevalence in Mongolian populations.
The clinical manifestation of alopecia areata is very characteristic. An initial round or oval bald spot appears without any symptoms whatsoever and is usually discovered quite by chance. The sudden loss of hair over a circumscribed area can affect any type of hair, e. g. on the head or face, the eyelashes, etc. The skin at the site of the focus is intact and free from any signs of inflammation or atrophy.
The primary focus develops most frequently on the scalp and is sharply circumscribed against the surrounding, normally hairy skin. As the condition progresses, the hairs at the margin of the focus thin out slightly. A spread of the process causes anagen hairs to change quickly to telogen and leads to the formation of dystrophic hairs. In the acute phase of alopecia areata, large numbers of club hairs are diffusely distributed over the whole scalp, with the maximum round the focus, where they can easily be pulled out. The broken shafts of dystrophic hairs, shaped like exclamation marks, can often be seen in the marginal zone of the bald patch; these are typical of alopecia areata.
The primary focus generally spreads centrifugally, but sometimes further bald patches are formed in its vicinity and merge to form areas with irregular outlines. In many cases, centrifugal progression is accompanied, in the centre of the same focus, by a spontaneous repair process clinically manifested in a thin growth of short, fine, unpigmented lanugo. If the course of alopecia is benign, the lanugo is gradually replaced by normal terminal hairs with the same pigmentation as those around them. In elderly, greyhaired subjects, pigmentogenesis takes longer to recover.
The course of alopecia areata is highly individual and one must always reckon that the original focus will spread and that further bald spots will develop on the scalp and on other parts of the body. The first attack is usually benign, i. e. hair grows again on the primary focus and no further spots are formed. There is no guarantee, however, that the condition will not recur (sometimes after years), with a severer course and a poorer prognosis; in such cases hair grows again on some foci, but others generally progress, or new ones are formed and merge to form confluent alopecia covering a large area. A spread of the process on the scalp to further follicles leads to total alopecia and involvement of other types of hair to universal (i.e. malignant) alopecia.
Alopecia areata may progress slowly and steadily or occur in sudden attacks, but severe forms very often develop acutely and abruptly, with rapid progression on the scalp and a somewhat slower course in other localizations.
In children, alopecia areata may follow a typical course, but it may also be atypical if the affected areas are indistinctly circumscribed and are covered by the long remaining hair. In such cases it is somewhat hard to decide whether or not the child has trichotillomania. The diagnosis of ophiasis (alopecia areata liminaris) in children is easier, since it affects the marginal hair of the scalp in the occipital region and spreads behind the ears. Ophiasis has a poor prognosis, as regards both healing of the actual focus and the further course of alopecia.
The other types of hair can be affected by alopecia either individually, or combined in various ways, but usually together with the scalp hair. Involvement of the eyelashes and eyebrows is very common in total alopecia.
Dystrophic changes occur in the nails in over 60% of cases of alopecia areata. They are manifested most frequently in inconspicuous pitting, crossgrooving or splitting of the free edge of the nails. Dystrophic changes are practically always present in “florid” forms of alopecia areata.
Ophthalmological changes, in particular involvement of the lens leading to subcapsular cataract, are not a frequent concomitant finding, but patients with universal alopecia ought definitely to have their eyes examined.
Except for atopy and vitiligo, which occur very often together with alopecia areata (atopy in 11%, vitiligo in 4% of the cases), the other clinical and laboratory findings are inconstant and are rather Indicative of accidental coincidence.
It is interesting to note the frequent incidence of alopecia areata in Down’s syndrome (mongolism, chromosome 21 trisomia) and, together with vitiligo and other serious signs, in the Vogt Koyanagi syndrome, which is evidently of virus origin. Considerable attention has been paid to the relationship of alopecia areata to atopy and vitligo and hypotheses on the aetiopathogenesis of the disease have been based on it.
The prognosis of alopecia areata is always uncertain and premature conclusions should never be drawn on its outcome. All authors, however, are agreed that alopecia appearing before puberty has a poorer prognosis than cases which start in adulthood. If the first attack occurs in early childhood, one must always reckon with recurrences. The disappearance of lanugo from alopecic patches and the localization (age) factor in ophiasis are unfavourable signs. Abrupt progression and involvement of the eyelashes, eyebrows and nails are also ;prognostically unpromising features. In total forms the hair seldom grows again spontaneously and in universal forms practically never.
The differential diagnosis is not difficult, but in atypical childhood forms the possibility of trichotillomania should always be borne in mind. The clinical picture of cicatricial alopecia does not resemble alopecia areata and where there is erythema and desquamation in the focus one must exclude a possible reaction to therapy and other diseases, such as chronic discoid lupus erythematosus. The greatest difficulties arise with wrongly diagnosed diffuse forms of alopecia areata which, if they have a stormy course, resemble postintoxication alopecia or, if progression is slower, diffuse alopecia of some other origin.
Pathology. In patches of alopecia areata, hair production in the follicles does not stop, but the hairs are of miniature size and are not fully keratinized. In the initial stage, lymphocytic infiltrates appear in the vicinity of the follicle, in the matrix and in the outer epithelial sheath; in the papilla, histiocytes and oedema may be found as well. Electron microscopy demonstrated impairment of the basal membrane between the matrix and the papilla and relatively severe changes of a degenerative character in the epithelial cells of the bulb; the papilla resembled the catagen stage.
In chronic processes, fibrocyte like mesenchymal cells and a large quantity of collagen fibrils were observed in the electron microscope. In addition to mitoses and lymphoid infiltrates, the epithelial cells of the bulb contained autophagic vacuoles.
As distinct from androgenic alopecia, in which the entire bulb and the papilla shrink in keeping with the reduced size of the hair, in alopecia areata disproportion develops between the relatively large papilla and the small bulb, i. e. the papilla is anagenic and the bulb dystrophic.
Keratinization in the keratogenic zone is not perfect and the hair either emerges, but snaps off above the surface of the skin (“exclamation mark hair”), or already breaks up in the follicle, filling it with keratin debris. The presence of mitoses and a raised amount of alkaline phosphatase shows that the miniature follicles are active and explains their regenerative capacity.
The aetiology of alopecia areata is still unknown, but it is assumed that it is an autoimmune reaction to melanin which is lost from the atrophic follicle and passes into the papilla. In this respect there seems to be an association with vitiligo, which is also regarded as an autoimmune response to melanin. There are numerous objections to this theory, however; for instance, the first new hair to grow on the foci of alopecia is white, but that is not adequate evidence of the autoimmune origin of the disease, although new growth can be induced with corticoids.
According to another theory based on the change in sweating at the site of the foci and on other material, alopecia areata is of neurogenic origin. It is true that neurogenic factors can lead to abnormal hair growth, but there seem to be other factors, which inactivate the follicles. This inactivity can be reversed by corticoids — sometimes after years — but the mechanism by which this is effected is still unknown.
The absence of pigment in the hairs which grow on patches of alopecia areata is attributed to injury or dysfunction of the melanocytes. Since there is a close relationship between the metabolic processes of biogenic amines of the sympathetic system and melanin precursors, it is possible that the activity of the melanocytes is influenced by neurogenic factors.
The treatment of alopecia areata has little success and consequently new therapeutic techniques which, it is hoped, will have more permanent results, are continuously being sought and tested. Prior to the corticoid era, treatment was confined mainly to external methods, which irritated the skin and made it hyperaemic. The most diverse substances were employed, including dry ice, kelene, nicotinic acid and the intracutaneous injection of histamine, acetylcholine or pilocarpine. The results of such forms of therapy are somewhat problematical owing to the possibility of spontaneous remission of the disease. One of the more successful forms of external treatment of focal alopecia areata is the use of UV contact lamps (Finsen’s or Kromayer’s lamp). The results gave rise to the introduction of external or systemic therapy combining psoralens with longwave UV (UVA) radiation (PUVA), which today is evaluated very positively. Apart from PUVA therapy dinitrochlorbenzene (DNCB) sensitization is being tried out, with varying success. The systemic and intralesional administration of corticoids has now been virtually discarded because of the excessively high risk entailed in their side effects; they are now used mostly externally, their better resorption being assured by occlusive dressings.
Incidence. Alopecia areata is diagnosed in 2—3% of new dermatological patients of all ages and has even been found in infants and toddlers. In about 38% of all new cases the first signs appear before the age of 20. Alopecia areata occurs in people of every race, with a mild prevalence in Mongolian populations.
The clinical manifestation of alopecia areata is very characteristic. An initial round or oval bald spot appears without any symptoms whatsoever and is usually discovered quite by chance. The sudden loss of hair over a circumscribed area can affect any type of hair, e. g. on the head or face, the eyelashes, etc. The skin at the site of the focus is intact and free from any signs of inflammation or atrophy.
The primary focus develops most frequently on the scalp and is sharply circumscribed against the surrounding, normally hairy skin. As the condition progresses, the hairs at the margin of the focus thin out slightly. A spread of the process causes anagen hairs to change quickly to telogen and leads to the formation of dystrophic hairs. In the acute phase of alopecia areata, large numbers of club hairs are diffusely distributed over the whole scalp, with the maximum round the focus, where they can easily be pulled out. The broken shafts of dystrophic hairs, shaped like exclamation marks, can often be seen in the marginal zone of the bald patch; these are typical of alopecia areata.
The primary focus generally spreads centrifugally, but sometimes further bald patches are formed in its vicinity and merge to form areas with irregular outlines. In many cases, centrifugal progression is accompanied, in the centre of the same focus, by a spontaneous repair process clinically manifested in a thin growth of short, fine, unpigmented lanugo. If the course of alopecia is benign, the lanugo is gradually replaced by normal terminal hairs with the same pigmentation as those around them. In elderly, greyhaired subjects, pigmentogenesis takes longer to recover.
The course of alopecia areata is highly individual and one must always reckon that the original focus will spread and that further bald spots will develop on the scalp and on other parts of the body. The first attack is usually benign, i. e. hair grows again on the primary focus and no further spots are formed. There is no guarantee, however, that the condition will not recur (sometimes after years), with a severer course and a poorer prognosis; in such cases hair grows again on some foci, but others generally progress, or new ones are formed and merge to form confluent alopecia covering a large area. A spread of the process on the scalp to further follicles leads to total alopecia and involvement of other types of hair to universal (i.e. malignant) alopecia.
Alopecia areata may progress slowly and steadily or occur in sudden attacks, but severe forms very often develop acutely and abruptly, with rapid progression on the scalp and a somewhat slower course in other localizations.
In children, alopecia areata may follow a typical course, but it may also be atypical if the affected areas are indistinctly circumscribed and are covered by the long remaining hair. In such cases it is somewhat hard to decide whether or not the child has trichotillomania. The diagnosis of ophiasis (alopecia areata liminaris) in children is easier, since it affects the marginal hair of the scalp in the occipital region and spreads behind the ears. Ophiasis has a poor prognosis, as regards both healing of the actual focus and the further course of alopecia.
The other types of hair can be affected by alopecia either individually, or combined in various ways, but usually together with the scalp hair. Involvement of the eyelashes and eyebrows is very common in total alopecia.
Dystrophic changes occur in the nails in over 60% of cases of alopecia areata. They are manifested most frequently in inconspicuous pitting, crossgrooving or splitting of the free edge of the nails. Dystrophic changes are practically always present in “florid” forms of alopecia areata.
Ophthalmological changes, in particular involvement of the lens leading to subcapsular cataract, are not a frequent concomitant finding, but patients with universal alopecia ought definitely to have their eyes examined.
Except for atopy and vitiligo, which occur very often together with alopecia areata (atopy in 11%, vitiligo in 4% of the cases), the other clinical and laboratory findings are inconstant and are rather Indicative of accidental coincidence.
It is interesting to note the frequent incidence of alopecia areata in Down’s syndrome (mongolism, chromosome 21 trisomia) and, together with vitiligo and other serious signs, in the Vogt Koyanagi syndrome, which is evidently of virus origin. Considerable attention has been paid to the relationship of alopecia areata to atopy and vitligo and hypotheses on the aetiopathogenesis of the disease have been based on it.
The prognosis of alopecia areata is always uncertain and premature conclusions should never be drawn on its outcome. All authors, however, are agreed that alopecia appearing before puberty has a poorer prognosis than cases which start in adulthood. If the first attack occurs in early childhood, one must always reckon with recurrences. The disappearance of lanugo from alopecic patches and the localization (age) factor in ophiasis are unfavourable signs. Abrupt progression and involvement of the eyelashes, eyebrows and nails are also ;prognostically unpromising features. In total forms the hair seldom grows again spontaneously and in universal forms practically never.
The differential diagnosis is not difficult, but in atypical childhood forms the possibility of trichotillomania should always be borne in mind. The clinical picture of cicatricial alopecia does not resemble alopecia areata and where there is erythema and desquamation in the focus one must exclude a possible reaction to therapy and other diseases, such as chronic discoid lupus erythematosus. The greatest difficulties arise with wrongly diagnosed diffuse forms of alopecia areata which, if they have a stormy course, resemble postintoxication alopecia or, if progression is slower, diffuse alopecia of some other origin.
Pathology. In patches of alopecia areata, hair production in the follicles does not stop, but the hairs are of miniature size and are not fully keratinized. In the initial stage, lymphocytic infiltrates appear in the vicinity of the follicle, in the matrix and in the outer epithelial sheath; in the papilla, histiocytes and oedema may be found as well. Electron microscopy demonstrated impairment of the basal membrane between the matrix and the papilla and relatively severe changes of a degenerative character in the epithelial cells of the bulb; the papilla resembled the catagen stage.
In chronic processes, fibrocyte like mesenchymal cells and a large quantity of collagen fibrils were observed in the electron microscope. In addition to mitoses and lymphoid infiltrates, the epithelial cells of the bulb contained autophagic vacuoles.
As distinct from androgenic alopecia, in which the entire bulb and the papilla shrink in keeping with the reduced size of the hair, in alopecia areata disproportion develops between the relatively large papilla and the small bulb, i. e. the papilla is anagenic and the bulb dystrophic.
Keratinization in the keratogenic zone is not perfect and the hair either emerges, but snaps off above the surface of the skin (“exclamation mark hair”), or already breaks up in the follicle, filling it with keratin debris. The presence of mitoses and a raised amount of alkaline phosphatase shows that the miniature follicles are active and explains their regenerative capacity.
The aetiology of alopecia areata is still unknown, but it is assumed that it is an autoimmune reaction to melanin which is lost from the atrophic follicle and passes into the papilla. In this respect there seems to be an association with vitiligo, which is also regarded as an autoimmune response to melanin. There are numerous objections to this theory, however; for instance, the first new hair to grow on the foci of alopecia is white, but that is not adequate evidence of the autoimmune origin of the disease, although new growth can be induced with corticoids.
According to another theory based on the change in sweating at the site of the foci and on other material, alopecia areata is of neurogenic origin. It is true that neurogenic factors can lead to abnormal hair growth, but there seem to be other factors, which inactivate the follicles. This inactivity can be reversed by corticoids — sometimes after years — but the mechanism by which this is effected is still unknown.
The absence of pigment in the hairs which grow on patches of alopecia areata is attributed to injury or dysfunction of the melanocytes. Since there is a close relationship between the metabolic processes of biogenic amines of the sympathetic system and melanin precursors, it is possible that the activity of the melanocytes is influenced by neurogenic factors.
The treatment of alopecia areata has little success and consequently new therapeutic techniques which, it is hoped, will have more permanent results, are continuously being sought and tested. Prior to the corticoid era, treatment was confined mainly to external methods, which irritated the skin and made it hyperaemic. The most diverse substances were employed, including dry ice, kelene, nicotinic acid and the intracutaneous injection of histamine, acetylcholine or pilocarpine. The results of such forms of therapy are somewhat problematical owing to the possibility of spontaneous remission of the disease. One of the more successful forms of external treatment of focal alopecia areata is the use of UV contact lamps (Finsen’s or Kromayer’s lamp). The results gave rise to the introduction of external or systemic therapy combining psoralens with longwave UV (UVA) radiation (PUVA), which today is evaluated very positively. Apart from PUVA therapy dinitrochlorbenzene (DNCB) sensitization is being tried out, with varying success. The systemic and intralesional administration of corticoids has now been virtually discarded because of the excessively high risk entailed in their side effects; they are now used mostly externally, their better resorption being assured by occlusive dressings.
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