#Give the etiology of vitiligo.#

Disturbed innervation is thought to be influential. The disease develops
often without apparent cause. Alopecia areata and morph[oe]a have been
observed associated with it.

[Illustration: Fig. 36. Vitiligo.]

#State the pathology of vitiligo.#

The disease consists, anatomically, of both a diminution and increase of
the pigment--the white patch resulting from the former, and the
pigmented borders from the latter. There is no textural change, the skin
in other respects being normal.

#From what diseases is vitiligo to be differentiated?#

From morph[oe]a and from the anaesthetic patches of leprosy.

#In what respects do these diseases differ from vitiligo?#

In morph[oe]a there is textural change, and in leprosy both textural
change and constitutional or other symptoms.

#What prognosis is to be given?#

It should always be guarded, the disease in almost all cases being
irresponsive to treatment.

#What is the treatment of vitiligo?#

The general health is to be looked after, and remedies directed
especially toward the nervous system to be employed. Arsenic, in small
and continued doses, seems at times to have an influence; when there is
lack of general tone it may be prescribed as follows:--

[Rx] Liq. potassii arsenitis, ............. f[dram]j
Tinct. nucis vom., ................... f[dram]iij
Elix. calisayae, ....... q. s. ad ..... f[Oz]iv. M.

SIG.--f[dram]j t. d.

Suprarenal-gland preparations in moderate dosage long continued has
appeared in a few instances to be of some benefit.

When upon exposed parts, stimulation of the patches, with the view of
producing hyperaemia and consequent pigment deposit; conjoined with
suitable applications to the surrounding pigmented skin, with a view to
lessen the coloration (see _treatment of chloasma_), will be of aid in
rendering the disease less conspicuous. Or the condition may be, in a
measure, masked by staining the patches with walnut juice or similar
pigment.

#Canities.#
(_Synonym:_ Grayness of the Hair.)

#Describe canities.#

Canities, or graying of the hair, may occur in localized areas or it may
be more or less general; the blanching may be slight, scarcely amounting
to slight grayness, or it may be complete. It is common to advancing
years (_canities senilis_); it is seen also exceptionally in early life
(_canities prae