ALOPECIA AREATA.
Definition. — A disease of the hair characterized by the rapid development of more or less circular or oval bald patches on the scalp and sometimes in other parts of the body.
Symptoms. — Alopecia areata usually presents itself in the form of rounded or oval patches, situated on the scalp OT other hairy regions of the body. The skin of these patches is white and smooth, and in some cases discolored and some what depressed. At times the affection extends over the entire cutaneous surface.
The hairs become dry and colorless, their roots are atrophied, and they rap idly fall out.
Three main forms of alopecia areata have been recognized: alopecia areata archromatica (Bazin), in which the bald patches are discolored and excavated, as described above; false alopecia areata, in which the patches of baldness are more or less covered with thin, brittle hairs, which can easily be pulled out along with their roots: a form of ringworm. The third variety is alopecia areata de calvans, in which the entire scalp, or the skin of other parts of the body, becomes bald in a few days, the hair falling with great rapidity.
In alopecia areata the hairs are dry, lustreless, thin, and brittle. Their roots are either atrophied and thread-like or swollen into irregular nodules. The medulla has disappeared, and air-bubbles may be seen in their interior. They fre quently break close to the scalp, their free extremity being brush-like in ap pearance.
In the so-called false alopecia areata the few hairs left retain their hue and consistency.
Deductions based on a study of 257 eases:— Four classes of cases are included under the generic name alopecia areata: 1. Universal alopecia; it is very rare.
2. Baldness occurring in one or more patches at the site of an injury or in the course of a recognizable nerve. This is comparatively infrequent.
3. A form first described by Neumann as "alopecia circumscripta seu orbicu laris." The patches are small, from lentil- to pea- size, much depressed below the surface, with often a marked de crease of the sensibility. The prognosis
is unfavorable.
The first three classes form less than 10 per cent. of all the cases classed as alopecia areata. They are undoubtedly of trophoneurotic origin.
4. The largest, numerically, is due to a vegetable parasite. Crocker (Lancet, Feb. 28, Mar. 7, '91).
Two cases in which the nails were af fected in patients suffering from alopecia areata of the scalp. One was a delicate nervous young woman. The nails became affected some months after alopecia had manifested itself on her scalp. The sec ond case was that of a young man who had a typical patch of alopecia areata on the scalp. The nails in both cases presented a discolored gran:te-like ap pearance due to minute punctiform depressions, which gave them a dirty, unpolished look. C. Audry (Jour. des Malad. Cutan. et Syph., Mar., 1900).
Diagnosis.—Alopecia areata should be distinguished from syphilitic alopecia; but usually in this latter affection the patches are merely thinned out and arranged irregularly over the head in streaks; other symptoms of syphilis are frequently present.
The alopecia in patches resembles, in a certain way, alopecia areata, but it has certain characters which are perfectly pathognomonic. Alopecia areata makes a clean sweep, all the hairs on the patch falling out. In syphilis, however, some hairs always remain on the affected patches, which also are never so regular, rounded, or extensive as those of alopecia areata. Another diagnostic point is that the area-like alopecia of syphilis is al ways accompanied by the disseminate form, whereas in alopecia areata the hair is usually normal up to the very edge of the bald spot. Finally, alopecia areata decolorizes the skin, which be comes dead-white, while the bald areas of syphilis retain their natural color. Fournier (L'Union MM.. Dec. 4, '90).
Premature Idiopathic Alopecia.—From ordinary alopecia, alopecia areata should be recognized by its white, smooth ap pearance and rounded, limited form.