a is an inflammatory affection characterized by evanescent
whitish, pinkish or reddish elevations, or wheals, variable as to size
and shape, and attended by itching, stinging or pricking sensations.

#Describe the symptoms of urticaria.#

The eruption, erythematous in character and consisting of isolated pea
or bean-sized elevations or of linear streaks or irregular patches,
limited or more or less general, and usually intensely itchy, makes its
appearance suddenly, with or without symptoms of preceding gastric
derangement. The lesions are soft or firm, reddish or pinkish-white,
with the peripheral portion of a bright red color, and are fugacious in
character, disappearing and reappearing in the most capricious manner.
In many cases simply drawing the finger over the skin will bring out
irregular and linear wheals. In exceptional cases this peculiar property
is so pronounced and constant that at any time letters and other symbols
may be produced at will, even when such subjects are free from the
ordinary urticarial lesions (_urticaria factitia_, _dermatographism_,
_autographism_).

The mucous membrane of the mouth and throat may also be the seat of
wheals and urticarial swellings.

#What is the ordinary course of urticaria?#

Acute. The disease is usually at an end in several hours or days.

#Does urticaria always pursue an acute course?#

No. In exceptional instances the disease is chronic, in the sense that
new lesions continue to appear and disappear irregularly from time to
time for months or several years, the skin rarely being entirely free
(_chronic urticaria_).

[Illustration: Fig. 12.
Dermatographism. (_After C.N. Davis._)]

#Are subjective symptoms always present in urticaria?#

Yes. Itching is commonly a conspicuous symptom, although at times
pricking, stinging or a feeling of burning constitutes the chief
sensation.

#In what way may the eruption be atypical?#

Exceptionally the wheals, or lesions, are peculiar as to formation, or
another condition or disease may be associated, hence the varieties
known as urticaria papulosa, urticaria haemorrhagica, urticaria tuberosa,
and urticaria bullosa.

#Describe urticaria papulosa.#

Urticaria papulosa (formerly called _lichen urticatus_) is a variety in
which the lesions are small and papular, developing usually out of the
ordinary wheals. They appear as a rule suddenly, rarely in great
numbers, are scattered, and after a few hours