What Is Prurigo Simplex?

Prurigo simplex is a pruritus disorder of the skin characterized by extremely itchy skin nodules and lesions. Typically, there is no known direct cause of prurigo simplex, but some factors are known to trigger or aggravate it. This condition falls between chronic and acute, sometimes transitioning into a chronic condition. Many people experience a recurrence of the condition after periods of remission. Middle-aged patients are the most prone age group to this condition.

The most common prurigo simplex symptoms are skin nodules resembling insect bites that are intensely itchy. These nodules are frequently scratched open, becoming lesions that continue to itch. Sometimes the skin thickens and becomes discolored around the nodules. The scalp, arms, legs and trunk of the body are the most frequent sites of the bumps and lesions. Itching can become severe and habitual, worsening the condition and possibly causing infections in the open sores.

Sometimes the nodules become less itchy and eventually disappear leaving a discolored area or scar tissue. The same nodules can persist for months or even years, though, without healing. Patients may experience a remission but then relapse with new nodules forming. The condition might also become chronic, with no periods of improvement and relief.

Although the exact causes of prurigo simplex have not been determined, it is believed that there are many aggravating factors that can trigger the condition. Extremes of cold, heat or sunlight are factors in some cases. Food, drug and other allergies may trigger prurigo simplex. The condition also seems to be triggered or aggravated by emotional stress. Chronic infections such as sinusitis and endocrine or metabolic disorders may also play a role.

Prurigo simplex treatment is sometimes difficult, as common treatments for other skin conditions are not always effective. Corticosteriod creams and ultraviolet light treatments sometimes work. One promising treatment is psoralen photochemotherapy in the form of foil bath psoralen ultraviolet A (PUVA). The patient is bathed in a psoralen solution then exposed to ultraviolet A radiation in a series of treatments. Psoralen is a plant-derived compound that makes the cells more sensitive to the effects of ultraviolet light.

Additional prurigo simplex treatments include steroid injections in the nodules, as well as antihistamines and tranquilizers. Patients are advised to avoid strong sunlight, temperature extremes, and activities that cause the body to overheat. If emotional stress is one of the triggers, learning to manage stress may help alleviate the symptoms. Determining if allergies contribute to the problem, then avoiding the allergen might result in improvement of prurigo simplex.