to give rise to
simple dryness or harshness of the skin (_xeroderma_); but as commonly
met with it is more developed, more or less marked scaliness in the form
of thin or somewhat thick epidermal plates being present. The papillae of
the skin are often slightly hypertrophied. In slight cases the color of
the scales is usually light and pearly; in the more marked examples it
is dark gray, olive green or black.

In the severe variety--ichthyosis hystrix--in addition to scaliness
there is marked papillary hypertrophy, forming warty or spinous patches.
This type is rare, and, as a rule, the surface involved is more or less
limited.

#Are there any inflammatory symptoms in ichthyosis?#

No. In fact, beyond the disfigurement, the disease causes no
inconvenience; in those well-marked cases, however, in which the scales
are thick and more or less immovable, the natural mobility of the parts
is compromised and fissuring often occurs. In the winter months, in the
severer cases, exposed parts may become slightly eczematous.

#Does ichthyosis vary somewhat with the season?#

Yes. In all cases the disease is better in the warm months, and in the
mild forms may entirely disappear during this time. This favorable
change is purely mechanical--due to the maceration to which the
increased activity of the sweat glands gives rise.

#Is the general health affected in ichthyosis?#

No.

#What course does ichthyosis pursue?#

Chronic. Beginning in early infancy or childhood, it usually becomes
gradually more marked until adult age, after which time it, as a rule,
remains stationary.

#What is the etiology?#

Beyond a hereditary influence, which is often a positive factor, the
causes are obscure. It is not a common disease.

#State the pathology.#

Anatomically the essential feature is epidermic hypertrophy, with
usually a varying degree of papillary hypertrophy also.

#Mention the diagnostic features of ichthyosis.#

The harsh, dry skin, epidermic and papillary hypertrophy, the
furfuraceous or plate-like scaliness, the greater development upon the
extensor surfaces, a history of the affection dating from early
childhood, and the absence of inflammatory symptoms.

#How is ichthyosis to be distinguished from eczema, psoriasis, and other
scaly inflammatory diseases?#

By the absence of the inflammatory element.

#What is the outlook for a case of ichthyosis?#

The prognosis is unfavorable as regards a c