Page 123 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 4-38 Rashes

IRRITANT CONTACT DERMATITIS

Irritant contact dermatitis is one of the most commonly
encountered dermatoses in the dermatology clinic. Its
true incidence is unknown. Irritant contact dermatitis
can be caused by a multitude of factors, and the mor-
phology of its appearance can be varied. One of the
most common forms of irritant contact dermatitis is
seen on the hands and is caused by occupational expo-
sures to irritant chemicals or excessive hand washing. Hand dermatitis
Clinical Findings: Irritant contact dermatitis can
occur at any age. Some studies show that women are
more commonly affected. There is no racial predilec-
tion. There are many exposures that can eventually lead
to the development of irritant contact dermatitis. The
final clinical manifestations are similar despite the dif-
ferent instigating chemicals. Variations exist in the loca-
tion of the dermatitis. The hallmark of irritant contact
dermatitis is xerosis. Once the skin dries out to a certain
point, it becomes inflamed. This leads to the clinical
picture of dry pink or red patches. On the hands,
painful fissures or splits may occur within the skin lines.
Diaper dermatitis in infants is one specific form of
irritant contact dermatitis. The wet diaper rubbing
against the child’s buttocks and legs can cause skin irri-
tation, red patches, and occasionally erosions. The child
can become irritable with pruritus and is at higher risk Most babies will have diaper rash at
for secondary bacterial infections. least once. Synthetic absorbent materials
Many chemicals are direct irritants to the skin, and in disposable diapers or germ-killing
injuries from these agents are occasionally seen in a rinses can also cause irritation. The
dermatologist’s office. Exposure of the skin to hydro- rash can be uncomfortable or painful.
chloric acid results in skin cell death, necrosis, and
inflammation. This, in turn, leads to the development
of red patches or plaques with varying amounts of
erosion and ulceration. These patients often receive
care in an occupational work setting or in the emer-
gency room. The same can be said for exposure of the
skin to strong basic chemicals such as sodium hydrox-
ide. Basic chemicals can cause an irritant contact der-
matitis that is directly related to the necrotic effect of
the chemical on the skin surface.
One of the most common causes of irritant contact
dermatitis is frequent hand washing. The use of soaps
removes the natural oils and waxes that the skin pro-
duces as a way of physiologically keeping the skin from
drying out. Once the removal of these oils outweighs
their production, dryness begins to set in. If the skin is
not given enough time to repair itself, the epidermis
continues to dry out and becomes inflamed. Pink to red
patches are evident, and, as the irritation continues, the
dryness worsens until fissuring and cracking occur. Irritant hand dermatitis due to purposeful
Ring dermatitis is another common form of irritant exposure to sodium hydroxide. Note the
contact dermatitis. It is believed that soap residue builds macerated skin with small erosions and
up between the surface of the ring and the skin. This a clear demarcation at the wrist where
prolonged contact causes an irritant contact dermatitis the individual was dipping his hands
underlying the ring. It can be misdiagnosed as an aller- into sodium hydroxide.
gic contact dermatitis, and on initial presentation, these
two forms of dermatitis cannot be differentiated. The
main differential diagnosis is between an irritant and an
allergic contact dermatitis. The two have similar clini-
cal appearances and can be almost impossible to dif- soap and water leads to a similar inflammatory frequent diaper changes may be all that is needed to
ferentiate. Irritant contact dermatitis typically has an cascade. The damaged keratinocytes release myriad resolve irritant contact diaper dermatitis. Hand derma-
acute onset and a decrescendo resolution, unless there inflammatory cytokines. The intensity of the reaction titis can be treated with a combination of moisturizers,
is repeated exposure to the irritant. Allergic contact is based on the concentration of the irritant and the topical corticosteroids, and avoidance of frequent hand
dermatitis usually has a crescendo-decrescendo clinical exposure time. The recruitment of T cells occurs later washing. If these changes can be accomplished, the
course. These patterns can be helpful in differentiating in the time course of irritant contact dermatitis, when prognosis is excellent. Workers with potential occupa-
the two conditions. compared with allergic contact dermatitus. tional exposures to irritant chemicals must be properly
Pathogenesis: Exposure to an irritant chemical, Treatment: The goal of treatment is to remove the trained in handling them and given the correct protec-
whether an acid or a base, or repeated exposure to skin from exposure to the irritant. Barrier creams and tive gear to prevent exposure.

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 109