(Alopecia circumscripta; Tinea decalvans; Prurigo decalvans; Area Celsi).
Definition. A condition of the hairy surface, characterized by one or more circumscribed, rounded areas of complete baldness without any apparent change in the skin.
Symptoms. There usually appears without local sensation, although occasionally moderate itching or other manifestations may be present, one or more, small, round, smooth, white spots entirely denuded of hair. The skin is apparently sound and the lesions are irregularly distributed but commonly located on the scalp, especially in the occipito-parietal regions, although other parts of the body may be attacked at the same time. The male beard or the eyebrow, axillae, pubes or even the downy surfaces in either sex may be subsequently involved. Occasionally the patches remain stationary but usually they increase by peripheral extension. This method of growth is characteristic of true alopecia areata and, although the lesions usually keep the rounded or perhaps oval shape, they may form irregular areas by union with other patches. Rarely the condition is more pronounced at one or more sections of the periphery, forming single or multiple zigzag extensions in several directions. The patches involved appear polished, thin, softened and somewhat depressed. Sensitiveness to irritants is diminished to a marked degree. Short hairs which can be removed by the slightest traction are noted at the border of the spreading patch and occasionally some of the longer hairs come out easily. Exceptionally, a few of the short hairs may be seen on the central part of the area.
When the lesion becomes stationary, the short hairs no longer appear, the longer hairs are not so easily pulled out and recovery ensues. This may be demonstrated as the spots become smaller from peripheral hair growth, but in most favorable cases the hair appears all over the patch at once. The new hair is fine, of lighter color, sometimes even white, and frequently falls out to remain absent for a variable period before its renewal, when it appears to be nearer the normal shade. This performance of shedding may be repeated a number of times before the hair becomes permanent. The return of pigment may be observed if the successive growths are carefully watched. Occasionally as the hair is restored, other areas of baldness appear as recurrences or rather reactivities are quite common and the same spots may be affected a second time.
Among the atypical forms may be mentioned that in which the alopecia spreads in a band-like girdle around the head just within the hair line. Another form is represented in pea- to bean-sized patches which remain white and resemble scar tissue. When these are distinctly depressed, some what anesthetic and run a persistent and unfavorable course, they constitute the alopecia circumscripta seu orbicularis of Neumann. Other atrophic forms of alopecia result from injuries to a nerve, neuralgia or neuritis and present linear or irregular shapes unlike the true primary patches of alopecia areata. Certain neurotic conditions such as vitiligo, morphea and thyroid disease have been noted as coexisting with irregular alopecia and a number of examples of white, spotty, granular nail changes have been reported.
Etiology and Pathology. Both sexes at any age may be affected but the disease is more prevalent between the ages of ten and thirty. It probably does not number more than 1 per cent. of all cases in this country but is much more common in Europe. There are two etiological theories; one regards alopecia areata as parasitic and contagious and the other as trophoneurotic and non- contagious, and there are no doubt many plain examples of each. From my own experience I should say that the contagious variety is the more common, although it is less prevalent in the United States than in England, Germany and France. Numerous cases demonstrating contagion have been reported, such as several children in the same family, ten patrons of one barber, instances where two or more people intimately associated have contracted the disease, and outbreaks occurring in schools. The nature of the parasite is not definitely decided, many of the European authorities believing that true alopecia areata is related to ringworm. Others describe fungi or micrococci which have been occasionally found. Hutchinson claims that ringworm of the scalp in childhood may result in adult alopecia areata, and Crocker held the view that adult alopecia areata is equivalent to ringworm in childhood. Most of the evidence to bear out these theories is inferential; an example of which is the well-known fact that in the countries where alopecia areata is most common, so also is ringworm. Sabouraud believes that this disease is due to the microbacillus that he found in acne, seborrhea and comedo, and considers it an acute form of seborrhea oleosa. No doubt the majority of cases are contagious, but only slightly so, owing to unknown favoring circumstances.