CLINICAL DERMATOLOGY > PSORIASIS
What is psoriasis?
Psoriasis is a recurring, non-contagious chronic inflammatory disease of the skin, semi-mucous membranes, and nails which can also compromise the joints. It is a disease that causes thickened and inflamed flaky lesions.
In psoriasis, there is an abnormally high rate of mitosis in epidermal cells due to a defect in the immune system that is located in the genes that control the immune system’s response. It is believed to be multifactorial in individuals with a genetic predisposition and is triggered or exacerbated by various environmental factors.
Pathogenesis of psoriasis
Psoriasis affects about 2% of the population and usually begins between the ages of 15 and 35, although it can also be found in children and the elderly.
The disease is not hereditary, but there is a genetic predisposition to suffer from it since a third of those affected have direct relatives with psoriasis.
Although little is clear, there are two basic facts:
- Epidermal hyperplasia due to an increase in the population of germs.
- The inflammatory infiltrate of the dermis.
The inflammation is mediated by CD4+ type Th1 lymphocytes that release proliferative cytokines that stimulate the proliferation of epidermal cells.
The inflammatory response is of cellular nature against an auto-antigen that is still unknown, or a super streptococcal antigen in the case of post-infectious guttate psoriasis.
This theory is supported by anatomopathological studies of biopsy samples as well as by the effectiveness of drugs that inhibit T lymphocyte activation, its clonal expansion, or the release of pro-inflammatory cytokines.
Types of psoriasis
- Plaque psoriasis.
It is the most common form. It affects 90% of patients.
It manifests in well-defined plaques that may affect an area of a few millimetres to several centimetres in diameter. If plaques cover a large surface of the body, it is called generalised psoriasis. Plaques usually appear first on the knees, elbows, scalp, and sacral region, but may occur anywhere on the body.
- Guttate psoriasis.
It receives this name as the lesions are small (less than 2 cm), numerous, and distributed throughout the body. It is more common in children and young people. It usually appears after an infection with streptococci bacteria, usually a pharyngitis/tonsillitis. It responds very well to treatment and may even spontaneously disappear. In some cases it transforms into plaque psoriasis.
- Psoriasis on the palms and soles
This form of psoriasis, also called palmoplantar psoriasis, can greatly interfere with work and personal life.
The foot affectation can even cause mobility problems.
If there are no other lesions that are typical of psoriasis on other parts of the body, it can be difficult to diagnose since it is very similar to chronic eczema. Treatment of this type of psoriasis is complex.
- Psoriasis on the nails.
The nail affectation varies greatly. Some have small “spots” on the nails similar to thimble marks, others experience a thickening of the nails and some yellow spots that correspond to the detachment of the nail from its bed.
Nail lesions can be associated with any type of psoriasis.
- Psoriasis of the scalp.
The affectation of the scalp is very common. It presents itself in the form of highly attached dry flaking (thick dandruff) on a red area of the scalp and usually produces itching. It can be confused with seborrhoeic dermatitis. It does not produce alopecia (permanent hair loss).
Treatment for psoriasis
Diagnosis and treatment of psoriasis in Valencia
• Dr. Gabriel Serrano Sanmiguel