Chronic spontaneous urticaria

Chronic spontaneous urticaria

Chronic Spontaneous Urticaria (CSU), also known as chronic idiopathic urticaria, is a condition characterized by the occurrence of hives (urticaria) for a period of six weeks or longer, without an apparent external trigger. The hives are often accompanied by angioedema, which is swelling in the deeper layers of the skin. CSU is a manifestation of the body's immune response, but the exact cause remains unknown in most cases.

Symptoms and Diagnosis

The primary symptom of CSU is the appearance of red, raised, and itchy welts on the skin that may vary in size and shape. These welts can appear anywhere on the body and often migrate and disappear within 24 hours, only to appear again in different locations. Angioedema, presenting as deeper swellings, can occur in about 40% of cases, affecting areas such as the eyelids, lips, and tongue.

Diagnosis of CSU is primarily clinical, based on the history and physical examination. Routine diagnostic tests are not specific for CSU but may be performed to rule out other causes of urticaria. The Autologous Serum Skin Test (ASST) is one method used to identify autoantibodies in some patients with CSU, indicating an autoimmune component.

Pathophysiology

The pathophysiology of CSU is complex and not fully understood. It is believed to involve immune dysregulation, leading to the release of histamine and other inflammatory mediators from mast cells and basophils. In some patients, autoantibodies against the high-affinity IgE receptor or IgE itself can cause mast cell degranulation. Other proposed mechanisms include genetic factors, infections, stress, and hormonal changes.

Treatment

Treatment of CSU aims to relieve symptoms and improve quality of life. First-line therapy typically involves second-generation H1 antihistamines, which are effective in controlling pruritus and reducing hives in many patients. For those who do not respond adequately to standard doses, the dose may be increased up to fourfold. If symptoms persist, additional treatments such as omalizumab, an anti-IgE monoclonal antibody, corticosteroids, or cyclosporine may be considered, although these have potential side effects and require careful monitoring.

Prognosis

The course of CSU is variable; for some individuals, symptoms may resolve spontaneously within a few months to years, while others may experience symptoms for decades. Although CSU is not life-threatening, it can significantly impair quality of life, leading to sleep disturbance, anxiety, and depression.

Epidemiology

CSU affects approximately 0.5 to 1% of the population at any given time, with a higher prevalence in females. It can occur at any age but is most common in adults between the ages of 20 and 40 years.