PsoriasisPsoriasis
is a common scaling skin disease, which is inherited and presents with recurrent
flare-ups. It is carried by about 3% of the world population,
equally shared among males and females (Ref.1, p.190). Apart from the genetic
predisposition there appears to be an environmental triggering factor needed to
cause a flare-up of the disease. For instance, a streptococcal pharyngitis in
childhood can trigger the first attack of psoriasis. Certain drugs such
as lithium carbonate (used in manic depressive illness), beta-blockers (used as
anti-hypertensive medication), anti-malarial drugs or even systemic corticosteroids
(that have been used for decades in the treatment of psoriasis) have been decribed
to cause flare-ups of psoriasis (Ref. 1, P. 192). Finally, lack of sunshine
or a particularly stressful life experience can trigger a bout of psoriasis. On
the other hand, the knowledge of having to suffer from a lifelong chronic skin
disease such as psoriasis often leads to a low self esteem with a tendency towards
chronic depression. In the last few years further research has shown that psoriasis
is associated with a cell-mediated auto-immune disease (involving T cell lymphocytes).
This has opened the door for new immunological treatment modalities (see below).
Signs and symptoms: The onset of psoriasis is typically
slow, starting with one or only a few lesions of a plaque with silvery scaly skin
cells on top and a reddish lesion underneath when the scales are scratched off.
The underlying lesion has a lot of blood vessels, which bleed easily in spots
with scratching, a phenomenon called "punctate bleeding". Here is a
link to a site where pictures of psoriasis are shown (after you looked at the
pictures of this link, use the back arrow in the left upper corner of your screen
to return to this page or simply close the page with the pictures): psoriasis
pictures. The lesions typically are sharply demarcated, roundish,
oval shaped or sometimes grotesquely shaped. By the age of 20 years about 30%
of psoriasis patients have developed their first lesions. Once they develop and
if left untreated, they tend to stay around for several months. Typically
the lesions will develop in certain areas such as the scalp behind the frontline
of the hair and behind the ears as well as at the elbows and over the knee caps.
They also tend to occur over the sacral area, the back of the thighs and over
the buttock areas and on the penis. In the nails a typical appearance of pitting
helps the physician in the diagnosis. Other areas of involvement are eye-brows,
the anal, genital and umbilical areas as well as under the axillas. Occasionally,
the whole body can be covered with psoriasis plaques and this conditon can potentially
be very dangerous requiring urgent admission to hospital and treatment by a dermatologist
(Ref. 1, p.193-194 and Ref. 2, p. 816). Diagnosis: Most
of the time the family doctor can diagnose psoriasis and treat this successfully.
However, psoriasis can present with atypical appearances, where a referral to
a dermatologist is needed for a definite diagnosis. This specialist sees many
of these more complex cases and often can diagnose the condition by only looking
at it. Should there be an unusual symptom constellation, a skin biopsy might be
done and this can pinpoint the diagnosis. Other skin diseases such as squamous
cell carcinoma, seborrheic dermatitis, syphilis, cutaneous lupus
erthematosus, pityriasis rosea and other similiarly looking skin diseases must
be differentiated. The skin pathology shows a thickening of the keratin layer
with an underlying inflammatory condition in the dermal layer. Vascular changes
where capillaries go on occasion high up to underneath of the skin surface lead
to a puctuate bleeding ("Auspitz sign") when the lesion is scratched.
Also, there are microabscesses in the inflammed area of the skin lesion and the
lesion is very well demarcated towards the healthy skin (Ref. 3, p. 1199). Psoriasis Treatment: Treatment has to be
an ongoing concern and the patient has to understand this. The mainstay
of therapy are various topical agents that are directly applied to the affected
skin. They consist of lubricating agents (such as petrolatum ointment), anthralin
(a tar product) in a concentration of between 0.1% to 1%. Further, topical
corticosteroid ointments, if there are only a few lesions, can be applied, but
when larger surfaces are affected the physycian needs to be aware that absorption
into the systemic circulation through the skin can occur and this can have a negative
effect on the hormone balance. Calcipotriol is a vitamin D derivative, which is
very effective in relieving about 65% of plaque psoriasis over a time period of
5 to 6 weeks. It is very safe and can be applied up to 3 fl.oz. (100 grams) per
week without worries of side-effects (Ref. 1, p. 202). Alongside this therapy
the treatment can be improved with the help of ultraviolet light therapy. This
is based on the observation that psoriasis patients tend to always be better in
summer when people expose themselves to sunlight. When more than 20% of
the skin surface is covered with psoriasis lesions, the limit is reached with
topical therapy and at this time a referral to a skin specialist is a necessity.
At times intralesional injections of corticosteroids might be used, but at other
times systemic immunomodulators have to be used to change the course of psoriasis. As
mentioned above an abnormality of the T cell immune system involving autoimmune
reactions against the skin involving the TNF (=tumor necrosis factor) has opened
up new therapy modailites that are still being refined by skin specialists. Monoclonal
antibody therapy involving Infliximab
, directed against TNF, is very effective against psoriasis. This medication has
been released by the FDA for rheumatoid arthritis and Crohns disease. The above
link shows that dermatologists in the US have found this medication to be useful
in difficult to treat psoriasis cases. Enbrel
is another anti-TNF medication, which has been accepted by the FDA for psoriasis
and psoriatic arthritis. Other immune modulators are alefacept
and efalizumab,
both of which work by inhibiting T cells. At a recent conference Dr. Y. Zhou pointed
out that there likely will be further new biological therapies developed for psoriasis
(Ref. 13). At the present time one of the limitations is the enormous cost of
these newer medications. A more conventional immunotherapy utilizing chemotherapeutic
agents is briefly described below. Methoxsalen (brandnames: Oxsoralen,
8-MOP), trioxsalen (brandname: Trisoralen) or methotrexate can be used orally
under close supervision of a skin specialist. Side effects such as bone marrow
suppression have to be monitored with occasional blood tests. In addition to this
peeling agents such as Keralyt gel (contains 6% salicylic acid) can remove the
excess skin layers down to the level of normal skin in combination with the other
medications and ointments mentioned. Discuss further details with your primary
care physician or your specialist. Here is a link with more info on psoriasis: http://www.psoriasis.org/home/ |
