Psoriasis.
Epidemiology,
presentation,
complication and
management.
Definition:
Psoriasis is a chronic, non-infectious
inflammatory dermatosis characterized by
well-demarcated erythematous plaques
topped by silvery scales.
Epidemiology:
Psoriasis affects 2% of the population in
Europe and North America, but is less
common in Africa and Japan.
The sex incidence is equal.
The condition may start at any age, even
in the elderly, but the peak onset is in the
2nd and 3rd decades. It is unusual in
children less than 8 years old.
Aetiopathogenesis:
Genetics: about 35% of patients show a family
history, and identical twin studies show a
concordance of 80%. There are strong
correlations with the HLA antigens CW6, B13
and B17.
Epidermal kinetics and metabolism. The
epidermal cell proliferation rate is increased 20
fold or more in psoriasis, and the germinative
cell population is expanded.
Precipitating factors:
Koebner phenomenon. Trauma to the epidermis
and dermis, such as scratch or surgical scar can
precipitate psoriasis in the damaged skin.
Infection. Typically, a streptococcal sore throat
may precipitate guttate psoriasis.
Drugs. Beta-blockers, lithium and antimalarials.
Sunlight.
Psychological stress.
Clinical presentation.
Psoriasis varies in severity from the trivial to the
life-threatening.
Presentation patterns of psoriasis include:
Plague.
Guttate.
Flexural.
Localized forms.
Generalized pustular.
Nail involvement.
Erythoderma.
Plaque.
Well-defined, disc-shaped plaques
involving the elbows, knees, scalp hair
margin or sacrum are the classic
presentation. The plaques are usually red
and covered by waxy white scales which if
which, if detached may leave bleedng
points.
Guttate.
Guttate psoriasis is an acute symmetrical
eruption of “drop-like” lesions usually on
the trunk and limbs. The form mostly
occurs in adolescents or young adults and
may follow a streptococcal throat infection.
Localized forms.
Psoriasis can also present in a number of
localized forms:
Palmoplantar pustulosis.
Acrodermatitis of Hallopeau.
Scalp psoriasis.
Napkin psoriasis.
Generalized pustular.
Generalized pustular is a rare but serious
and even life-threatening form of psoriasis.
Sheets of small, sterile yellowish pustules
develop on an erythematous background
and may rapidly spread. The onset is often
acute. The patient is unwell, with fever and
malaise, and requires hospital admission.
Nail involvment.
Psoriasis affects the matrix or nail bed in
up to 50% of cases. An oily or salmon pink
discoloration of the nail bed is seen, often
adjacent to onycholisis.
TREATMENT
Topical therapy:
1. topical corticosteroids
2. vit D analogues – dovonex.
3. keratolytic and scalp preparations – salicylic acid
ointment.
systemic therapy:
1. PUVA.
2. retinoids
3. methotrexate.
4. cyclosporin.