ration: Fig. 37. Alopecia Areata.]

Alopecia areata is an affection of the hairy system, in which occur one
or more circumscribed, round or oval patches of complete baldness
unattended by any marked alteration in the skin.

#Upon what parts and at what age does the disease occur?#

In the large majority of cases the disease is limited to the scalp; but
it may invade other portions of the body, as the bearded region,
eyebrows, eyelashes, and, in rare instances, the entire integument.

It is most common between the ages of ten and forty.

#Describe the symptoms of alopecia areata.#

The disease begins either suddenly, without premonitory symptoms, one or
several patches being formed in a few hours; or, and as is more usually
the case, several days or weeks elapse before the bald area or areas are
sufficiently large to become noticeable. The patches continue to extend
peripherally for a variable period, and then remain stationary, or
several gradually coalesce and form a large, irregular area involving
the entire or a greater portion of the scalp. The skin of the affected
regions is smooth, faintly pink or milky white, and at first presents no
departure from the normal; sooner or later, however, the follicles
become less prominent, and slight atrophy or thinning may occur, the
bald plaques being slightly depressed.

[Illustration: Fig. 38. Alopecia Areata--complete hair loss.]

Occasionally, usually about the periphery and in the early stages, a few
hair-stumps may be seen.

#What course does alopecia areata pursue?#

Almost invariably chronic. After the lapse of a variable period the
patches cease to extend, the hairs at the margins of the bald areas
being firmly fixed in the follicles; sooner or later a fine, colorless
lanugo or down shows itself, which may continue to grow until it is
about a half-inch or so in length and then drop out; or it may remain,
become coarser and pigmented, and the parts resume their normal
condition. Not infrequently, however, after growing for a time, the new
hair falls out, and this may happen several times before the termination
of the disease.

#Are there any subjective symptoms in alopecia areata?#

As a rule, not; but occasionally the appearance of the patches is
preceded by severe headache, itching or burning, or other manifestations
of disturbed innervation.

#State the cause of alopecia areata.#

The etiology is obscure. Two theories as to the cause of the d