- Is a chronic, recurrent disease, marked by epidermal proliferation.
- Its lesions, which appear as a erythematous papules and plaques covered with silver scales.
- This disorder commonly affects young adults, it may strike at any age, including during infancy.
- It is characterized by recurring partial remissions and exacerbations. Flare ups are commonly related to specific systemic and environmental factors but may be unpredictable; they can usually controlled by therapy.
- The tendency to develop psoriasis is genetically determined. Researchers have discovered a significantly higher than normal incidence of certain human leukocyte antigens (HLA) in families with psoriasis, suggesting a possible immune disorder. Onset of the disease is also influenced by environmental factors.
- Trauma can trigger the isomorphic effect or Koebner’s phenomenon, in which lesions develop at sites of injury. Infections, especially those resulting from beta-hemolytic streptococci,may cause a flare up of guttate (drop shaped) lesions. Other contributing factors include pregnancy, endocrine changes, climate (cold weather tends to exacerbate psoriasis), and emotional stress.
- Generally, the skin cells takes 14 days to move from the basal layer to the stratum corneum, where after 14 days of normal wear and tear, it’s sloughed off. The life cycle of normal skin cell is 28 days, compared to only 4 days for a psoriatic skin cell. This markedly shortened cycle doesn’t allow time for the cell to mature. Consequently, the stratum corneum becomes thick and flaky, producing the cardinal manifestations of psoriasis.
Signs and symptoms
The most common complaint of the patient with psoriasis is itching and occasional pain from dry, cracked, encrusted lesions.
- Plaques. Psoriatic lesions are erythematous and usually from well-defined plaques, sometimes covering large areas of the body. Such lesions usually appear on the scalp, knees, back, and buttocks. The plaques consist of characteristic silver scales that either flake off easily or can thicken, covering the lesion. Removal of psoriatic scales typically produces fine bleeding points (Auspitz sign). Occasionally, small guttate lesion appear, either alone or with plaques; these lesions are typically thin and erythematous, with few scales.
- Pustular Psoriasis. Rarely, psoriasis becomes pustular, taking one of two forms. In localized pustular psoriasis, pustules appear on the palms and soles and remain sterile until opened. In generalized pustular (Von Zumbusch) psoriasis, which commonly occurs with fever, leukocytosis, and malaise, groups of pastules coalesce to form lakes of pus on red skin. These pustules also retain sterile until opened and commonly involve the tongue and oral mucosa.
- Arthritic symptoms. Some patients develop arthritic symptoms, usually in one or more joints of the fingers or toes, in the larger joints, or sometimes in the sacroiliac joints, which may progress to spondylitis. Such patients may complain of morning stiffness.
- Diagnosis depends on patient history, appearance of the lesions and, if needed, the results of skin biopsy. In severe cases, the serum uric acid level is typically elevated due to accelerated nucleic acid degradation; however, indications of gout are absent. HLA antigens may be present in early-onset familial psoriasis.
Appropriate treatment depends on the type of psoriasis, the extent of the disease and the patient’s response to it, and the effect the disease has on the patient’s lifestyle. No permanent cure exists, and all methods of treatment are palliative.
- UVB exposure. Methods to retard rapid cell production include exposure to ultraviolet (UV) light (UVB or natural sunlight) to the point of minimal erythema. Tar preparations of crude coal tar itself may be applied to affected areas about 15 minutes before exposure or may be left on overnight and wiped off the next morning.
- A thin layer of petroleum jelly may be applied before UVB exposure ( the most common treatment for generalized psoriasis).
- Steroid creams and ointments are useful to control psoriasis. A potent fluorinated steroid works well, except on the face and intertriginous areas.
- Low dose anti-histamines, oatmeal baths, emollients, and open wet dressings may help relieve pruritus.
- Make sure that the patient understands his prescribed therapy; provide written instructions to avoid confusions.
- Teach the correct applications of prescribed ointment, creams, and lotions.
- Warn the patient never to put an occlusive dressing over anthralin. Suggest the use of mineral oil, then soap and water, to remove anthralin.
- Caution the patient to avoid scrubbing his skin vigorously, to prevent Koebner’s phenomenon.
- Watch for adverse reactions, especially allergic reactions to anthralin.
- Caution the patient receiving therapy to stay out of the sun on the day of treatment, and to protect his eyes with sun glasses that screen UVA for 24 hours after treatment.
- Because stressful situations tend to exacerbate psoriasis, help the patient cope with the situation.