Psoriasis a Multifactorial Disease

A dreaded disease with environmental, genetic, and immunologic factors playing a role, psoriasis is a disease that waxes and wanes with flare-ups, and it has no cure, as yet.

Psoriasis is a complex, chronic, proliferative, and inflammatory disease of the skin. It involves hyperproliferation of the keratinocytes in the epidermis and an increase in epidermal cell turnover rate. It is a multifactorial disease with environmental, genetic, and immunologic factors playing a role. Approximately 2-3% of the world’s population is affected by psoriasis. It most commonly affects the skin of elbows, knees, scalp, lumbosacral areas, intergluteal cleft, and glans penis. It is not limited to skin, as it can affect different systems beyond the skin. Psoriasis can present at any age, but usually follows a bimodal distribution. It peaks at around 20-30 years of age, and also around 50-60 years. There is no cure for psoriasis. The disease waxes and wanes with flare-ups.

Causes
The exact cause of psoriasis is unknown. However, genetic, environmental, and immunologic factors appear to play a role. Approximately 30% of the patients have a first-degree relative with psoriasis. Environmental factors like stress, cold, trauma, infections, alcohol, and drugs can trigger exacerbation, while hot weather and sunlight may be beneficial. Psoriasis is believed to be an autoimmune disease. Studies have shown high levels of dermal and circulatory TNF alpha in these patients.

Clinical features
Psoriasis is a papulosquamous disease with variable distribution, morphology, severity, and course. Lesion of psoriasis usually presents as chronic, symmetrical, well-circumscribed erythematous papules and plaques covered with dry silvery scales. Lesions are symmetrically distributed on scalp, knees, elbows, lumbosacral area, and body folds. Psoriasis, at times, can develop at the site of injury (known as the Koebner’s phenomenon). Itching is the common complaint, followed by pain in erythrodermic psoriasis and psoriatic arthritis. Decrease in quality of life and depression are common features. Pustular and erythrodermic psoriasis may present with high grade fever.
Joint is involved in 10-30% of patients. About 20% of patients may present with psoriatic arthritis before any skin rashes. Distal joints (fingers, toes, ankle, wrist, and knee) are most often affected with clinical features of pain, swelling, or stiffness. Ocular findings occur in approximately 10% of patients. Common symptoms are redness and tearing due to conjunctivitis and blepharitis.

Clinical types of psoriasis:
1. Plaque psoriasis
2. Guttate psoriasis
3. Flexural / inverse psoriasis
4. Erythrodermic psoriasis
5. Generalized pustular psoriasis
6. Palmoplantar pustulosis
7. Psoriatic nail
8. Scalp psoriasis
9. Oral psoriasis

Comorbodities
Inflammation in psoriasis is not limited to the skin, but can also affect different organ systems. Psoriasis patients have been found to exhibit increased hyperlipidemia, hypertension, coronary artery disease, type 2 diabetes, and increased body mass index.

Complications
Psoriasis can develop complications as follows:
• Secondary infection
• Risk of lymphoma
• Risk of cardiovascular and ischemic heart disease
• Psoriatic arthritis
• Inflammatory bowel disease
• Psychological disorder

Treatment
Psoriasis is a treatable, but not curable, disease. Treatment is individualized, depending upon the severity, surface area affected, and presence of comorbidities. Since psoriasis is a chronic relapsing disease, it often necessitates long term therapy. Mild to moderate psoriasis can be treated topically with a combination of steroid, vitamin D analogue, and phototherapy. Moderate to severe psoriasis often requires systemic therapies. Methotrexate, cyclosporin A, and retinoids are commonly-used systemic drugs for psoriasis. Coal tar and keratolytic agents like anthralin and urea are used adjunctly to treat psoriatic plaque. Moisturizers are the mainstay of treatment to help repair skin barrier function. Newer drugs like biologics are used in certain cases.

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