Pigmentation following radiation is especially influenced by
individual characteristics. It is common after reactions of all degrees. In
brunets diffuse homogeneous tanning may ensue from a fractional unfiltered
roentgen treatment. A similar small exposure may produce numberless ephelides
of various sizes and depths of brownish color in those subject to freckles. In
some the freckles may be of light brown color and rather large; in others they
may be very dark brown or black and pinhead-sized.
Pigmentation or
tanning usually disappears in a few weeks but may persist much longer. Not
infrequently the hyperpigmentation endures for a few years, especially in
brunets. After very severe reactions the pigmentation may be permanent.
In dark skins,
especially in Ethiopian and Mongolian races, depigmentation instead of
hyperpigmentation may ensue from intensive exposures. Such depigmentation is
permanent. It must be particularly guarded against in the treatment of keloids,
where it is customary to use fairly large doses.
Hyperpigmentation,
either diffuse or in the form of ephelides, is not an important index of skin
toleration, but it should not be completely disregarded in the treatment of
acne and other benign dermatoses where cosmetic effects are important. Cases
which show an early tendency to pigmentation should receive a little more
conservative treatment than those in which this biologic reaction is not
manifest.
Cutaneous Changes Representing the
Transient Functional Inhibitions Which, During Fractional Treatment, Precede
the Onset of True Radio-dermatitis. Although mild in character, they are of
the greatest importance in roentgen therapy, because they are about the only
clinical means of estimating the biologic response of normal skin structures
(sebaceous and sweat glands, hair follicles, and blood vessels) to doses which
are suitable for the radiotherapy of benign dermatoses.
Inhibition of
Functional Activity. The mildest form of clinical reaction is a dryness of the
skin caused by inhibition of the activity of the sudoriferous and oil glands.
This effect—which may be temporary or permanent—is noticed chiefly in treatment
with small doses over a long period at short intervals. Permanent inhibition
may result from repeated fractional filtered exposures of x-rays or radium
without causing an erythema.
Dryness
denotes that almost an erythema dose has been administered, and serves as a
warning that further radiation must be given cautiously with close observation
of the skin for evidence of irritability or erythema.
Epilation. The hair is epilated by
suberythema exposures of all except very soft radiation Lanugo, scalp and other hair are affected.
Defluvium usually occurs sixteen to twenty-one days after the administration of
an epilating dose. About the fourth week after exposure the hair ceases to
fall.
Defluvium from
suberythema exposures is always temporary. Even if there are mild reactions the
hair will usually regrow. It is necessary to bear in mind that an erythema,
however mild, may not be followed by complete regeneration. Erythemas are
therefore to be avoided in cases requiring temporary epilation.
Quality
of radiation also affects the character of these mild reactions. With soft
radiation from beryllium window tubes and grenz rays the action is so
superficial that the hair follicles are not appreciably affected. As a result,
this reaction consists of a superficial erythema. It appears within a few hours
after treatment and disappears in the course of one or two weeks. Erythemas
from unfiltered radium may also be so superficial that they do not cause
epilation. With orthodox qualities of radiations, defluvium occurs with all
doses sufficient to produce an erythema.
Permanent
alopecia is apt to follow severer types of radiodermatitis and even well-marked
erythemas, although occasionally a few scattered coarse hairs are seen growing
in atrophic, telangiectatic areas which have resulted from large doses.
Regrowth of hair usually occurs without
delay. Frequently it begins to grow in two or three weeks after it has fallen.
In general it may be said that regeneration takes place one to four months
after treatment. However, in cases which have shown no growth in this time,
some coarse hair may grow years later.
The regrowth
following even small doses may differ slightly from the original. Frequently it
is more profuse and occasionally it is curly in instances where it was formerly
straight, or may have a slightly different color or luster. It may grow more
rapidly and profusely in previously diseased areas than upon normal skin.
Irritability.
The serial administration of small doses of radiation may eventually lead to a
pronounced vascular irritability of the skin resembling a mild degree of
dermographism. In this state, rubbing or slapping of the treated area or the
application of warmth gives rise to rapid hyperemia. There may or may not be
slight itching.
Skin irritability
of this nature results from a larger dose than is required to produce
inhibition of the sweat and sebaceous glands. It may occur with an epilating
dose, especially if attempts at permanent epilation are under-taken. The
greatest importance attached to this type of skin irritability lies in its
significant warning that an erythema may develop at any time.
The local clinical reactions which have
been described are not usually included in a definition of radiodermatitis.
Inflammatory conditions of the skin produced by roentgen rays or radium rays
(radiodermatitis) are best divided into (a) acute dermatitis from a single
large dose or multiple large doses given at short intervals, and (b) chronic
dermatitis as a sequel of acute dermatitis or from frequently repeated small
doses given over a long period.