Psoriasis

Psoriasis is a non-infectious, chronic inflammatory disease of the skin, characterized by well-defined erythematous plaques with, silvery scale, with a predilection for the extensor surfaces and scalp, and a chronic fluctuating course.  Psoriasis is a common skin disease affecting about 1 to 2 per cent of the general population. Its onset is usually in the second to fourth decade of life.

histology

Etiology of Psoriasis

  • Genetic Predisposition common
  • Weather
  1. Exacerbations in winters.
  2. Remissions in summer.
  • Hormonal
  1. Remission or definite improvement during pregnancy.
  2. Worse at or after menopause.
  • Diet : common in non-vegetarians.
  • Precipitating Causes:
  1. Mental stress.
  2. Physical trauma.
  3. Fever.
  4. Infection.
  5. Drugs.

Clinical Features

Stable Plaque Psoriasis

This is the most common type. Individual lesions are well demarcated and range from a few millimetres to several centimetres in diameter. The lesions are red with dry, with silvery-white scale, which may be obvious only after scraping the surface. The elbows, knees and lower back are coomonly involved.

Other sites of Predilection include:

  • Scalp
  • Nails
  • Flexures
  • Palms

stable plaque psoriasis1

 

Guttate Psoriasis

This is most commonly seen in children and adolescents and may follow a streptococcal sore throat. In many patients this will be the first clinical indication of the disease. The rash often appears rapidly. Individual lesions are droplet-shaped, small (seldom greater than 1 cm in diameter) and scaly.

guttate psoriasis

Erythrodermic Psoriasis

The skin becomes universally red or scaly, or more rarely just red with very little scale present. As in other forms of erythroderma temperature regulations becomes problematic with a danger of either hypothermia or hyperthermia developing.

Erythrodermic Psoriasis

Pustular Psoriasis

There are two varieties of Pustular psoriasis .

Generalised form- It is rare but very serious. The onset is usually sudden with large numbers of small sterile pustules erupting on a red base. The patient may rapidly become ill with a swinging pyrexia coinciding with the appearance of new pustules.

Localised form- More common is a localised form of Pustular psoriasis which primarily affects the palm and soles. The eruption is chronic and comprises small sterile pustules which lie on a red base, and resolve to leave brown macules or scaling in their wake.

pustular psoriasis

Arthropathy  

Between 5% and 10% of individuals with psoriasis appear to have a chronic rheumatoid factor negative inflammatory arthropathy which can take on a number of patterns (i.e. central, as in ankylosing spondylitis, or peripheral, as in rheumatoid arthritis).

Arthropathy

Investigations

  • Biopsy- Biopsy is seldom necessary and often contributes little when there is genuine doubt about the diagnosis (for example, in attempting to distinguish between psoriasis and eczema of the palms and soles).
  • Throat swabbing- Throat swabbing for streptococci or other evidence of recent infection may occasionally be useful.

Preventions

  • Avoid exposure to cold.
  • Moderate, warm climate is beneficial.
  • Adequate exposure to sunlight.
  • Avoid undue stress.
  • Maintain good hygiene.
  • Hot bath in winters, drying, rubbing with towel and oiling.
  • Diet:
  1. Avoid fats, highly seasoned and salty dishes.
  2. High protein diet (cut down animal proteins).
  3. Avoid tea, coffee, alcohol.

References-

  • Davidson’s Principles & Practice of Medicine.
  • API textbook of Medicine.

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