Psoriasis

Psoriasis is a long-lasting, noncontagious autoimmune disease characterized by patches of abnormal skin. These areas are typically red, pink, or purple, dry, itchy, and scaly. The severity of psoriasis can vary significantly, ranging from small localized patches to extensive body coverage. The Koebner phenomenon, where injury to the skin triggers psoriatic changes at that spot, is a notable feature.

Signs and Symptoms

Plaque Psoriasis

Plaque psoriasis, or psoriasis vulgaris, is the most common form, affecting 85-90% of people with psoriasis. It appears as raised areas of inflamed skin covered with silvery-white scales. Commonly affected areas include the elbows, knees, scalp, and back.

Other Forms

• Inverse Psoriasis: Appears as smooth, inflamed patches in skin folds, such as around the genitals, armpits, and under the breasts.
• Guttate Psoriasis: Presents as small, scaly, red or pink droplet-like lesions, often triggered by streptococcal infection.

• Erythrodermic Psoriasis: Involves widespread inflammation and exfoliation, affecting over 90% of the body surface and can be life-threatening.

Psoriatic Arthritis

Psoriatic arthritis is a chronic inflammatory arthritis that occurs in association with skin and nail psoriasis. It typically involves painful inflammation of the joints and can result in dactylitis (sausage-shaped swelling of fingers and toes). About 30% of individuals with psoriasis develop psoriatic arthritis.

Nail Changes

Nail psoriasis can cause a variety of changes, including pitting, discoloration, subungual hyperkeratosis, onycholysis, and crumbling of the nails.

Causes

The exact cause of psoriasis is not fully understood, but it is believed to be a genetic disease triggered by environmental factors. Around one-third of individuals with psoriasis have a family history of the disease. Triggers include stress, infections, certain medications, and environmental factors. The underlying mechanism involves an immune system reaction to skin cells, leading to rapid skin cell production.

Diagnosis

Diagnosis is primarily based on the appearance of the skin. Typical characteristics include scaly, erythematous plaques that may be painful and itchy. In uncertain cases, a skin biopsy or scraping can confirm the diagnosis by ruling out other disorders.

Treatment

Topical Agents

Topical treatments include corticosteroids, vitamin D analogues, and emollients. These are effective for mild cases and are often used in combination.

Phototherapy

UVB phototherapy is commonly used for moderate psoriasis. PUVA therapy, combining psoralen with UVA light, is also effective but has a higher risk of long-term side effects.

Systemic Agents

Systemic treatments are used for severe cases and include methotrexate, ciclosporin, and biologics. Biologics target specific immune pathways and are effective but come with an increased risk of infections.

Prognosis

Most individuals with psoriasis have mild lesions treated effectively with topical therapies. Severe cases can lead to significant physical discomfort and disability, affecting quality of life. Psoriasis is associated with increased risks of cardiovascular disease, diabetes, and depression.

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Self-assessment MCQs (single best answer)

Which of the following best describes Multiple Sclerosis (MS)?

Which of the following is a common initial symptom of MS?

What is the main measure of disability and severity in MS?

Which virus is most strongly associated with an increased risk of developing MS?

Which diagnostic tool is primarily used to identify lesions characteristic of MS?

What is the purpose of disease-modifying therapies in the management of MS?

Which of the following is a characteristic finding in the cerebrospinal fluid (CSF) of MS patients?

Which of the following describes the primary progressive form of MS (PPMS)?

Which factor is NOT considered a risk factor for developing MS?

Which of the following treatments is typically used during an acute flare of MS?