C h a p t e r 4 6
Disorders of Skin Integrity and Function
1165
Treatment.
The goals for psoriasis treatment focus on
suppressing the hyperkeratosis, epidermal inflamma-
tion, and abnormal keratinocyte differentiation that
are characteristic of the disease. Usually, topical agents
are used first in any treatment regimen and when less
than 20% of the body surface is involved. They include
emollients, keratolytic agents, coal tar products, corti-
costeroids, and calcipotriene.
39
Emollients hydrate and
soften the psoriatic plaques. Keratolytic agents are peel-
ing agents that soften and remove plaques. Salicylic acid
is the most widely used. Coal tar, the by-product of
the processing of coke and gas from coal, is one of the
oldest yet most effective forms of treatment. The exact
mechanism of action of tar products is unknown, but
side effects of the treatment are few. Newer preparations
of coal tar lotions and shampoos are more aesthetically
pleasing, but the odor remains a problem.
Calcipotriene
(a vitamin D derivative)
ointment
has been shown to
inhibit epidermal cell proliferation and enhance cell
differentiation.
Tazarotene,
a synthetic retinoid, also
has been effective, but it is teratogenic and should be
avoided in women of childbearing age.
Topical corticosteroids are widely used and relatively
effective. They are generally more acceptable because
they do not stain and are easy to use. Low-potency
preparations usually are used on the face and on areas
of the body, such as the groin and axilla, where the
skin tends to be thinner. High-potency preparations are
reserved for treatment of thick chronic plaques that do
not respond to less-potent preparations. Although the
corticosteroids are rapidly effective in the treatment of
psoriasis, they are associated with flare-ups after dis-
continuation and they have many potential side effects.
Their effectiveness is increased when used under occlu-
sive dressings, but there is an increase in side effects.
Systemic treatments include phototherapy, photoche-
motherapy, methotrexate, corticosteroids, and cyclo-
sporine. The positive effects of sunlight have long been
established. Phototherapy with UVB radiation is a widely
used treatment. Newly developed narrow-band UVB
radiation is reportedly more effective than broad-band
UVB.
39
Photochemotherapy involves using a light-acti-
vated form of the drug methoxsalen. Methoxsalen, a pso-
ralen or phototoxic drug, exerts its actions when exposed
to UVA radiation in 320- to 400-nm wavelengths. The
combination treatment regimen of psoralen and UVA
is known by the acronym
PUVA
. Methoxsalen is given
orally before UVA exposure. Activated by the UVA
energy, methoxsalen inhibits DNA synthesis, thereby
preventing cell mitosis and decreasing the hyperkeratosis
that occurs with psoriasis. Although viewed as one of the
safest therapies since its introduction in the 1970s, PUVA
increases the risk for squamous cell carcinoma, and it
may increase the risk for development of melanoma.
Methotrexate, which is used for cancer treatment, is
an antimetabolite that inhibits DNA synthesis and pre-
vents cell mitosis. Oral methotrexate has been effective
in treating psoriasis when other approaches have failed.
The drug has many side effects, including nausea, mal-
aise, leukopenia, thrombocytopenia, and liver function
abnormalities. Cyclosporine is a potent immunosuppres-
sive drug used to prevent rejection of organ transplants.
It suppresses inflammation and the proliferation of
T cells in persons with psoriasis. Its use is limited to severe
psoriasis because of serious side effects, including neph-
rotoxicity, hypertension, and increased risk of cancers.
Intralesional cyclosporine also has been effective. Biologic
agents (drugs that are taken from or made of living tissues
or cells instead of chemicals) that target the activity of
T lymphocytes and cytokines responsible for the inflam-
matory nature of psoriasis have proven effective.
41
Pityriasis Rosea
Pityriasis rosea is a rash that primarily affects children
and young adults. The origin of the rash is unknown, but
is thought to be caused by an infective agent, possibly
a herpesvirus.
42
Its incidence is highest in winter. Cases
occur in clusters and among persons who are in close
contact; however, there are no data to support commu-
nicability, suggesting it may be an immune response to
any number of agents.
The characteristic lesion is an oval macule or papule
with surrounding erythema (Fig. 46-17). The lesion spreads
with central clearing, much like tinea corporis. This initial
lesion is called the
herald patch
and is usually on the trunk
or neck. As the lesion enlarges and begins to fade (2 to
10 days), successive crops of lesions appear on the trunk
and neck. The lesions on the back have a characteristic
FIGURE 46-16.
Psoriasis of the elbow. Note the irregular
red patches covered by a dry scaly hyperkeratotic stratum
corneum. (From the Centers for Disease Control and Prevention
Public Health Image Library. No. 4055. Courtesy of Susan
Lindsley.)
