Talk:Chronic prurigo

Chronic prurigo is a skin disease characterized by the presence of multiple pruritic (itchy), elevated lesions accompanied by chronic itch and a prolonged scratching behavior. There are different subtypes of chronic prurigo that can be identified according to the predominate lesion (papular prurigo, prurigo nodularis, plaque-type prurigo, umbilicated prurigo and linear prurigo)1.

Signs and Symptoms
The main signs and symptoms of chronic prurigo are the presence of chronic itch (≥ 6 weeks duration), evidence of a prolonged scratching behavior (for example, excoriations or scars) and multiple pruriginous lesions, which can occur localized to a body area or generalized over the entirety of the skin1. A typical pruriginous lesion is an elevated lesion (papule, nodule or plaque) with a pink or white center and a darkened (hyperpigmented) border. These lesions are often distributed in areas that can easily be scratched and occur symmetrically1. Other symptoms of chronic prurigo include sensory symptoms as burning, stinging or pain. The itch is often of very high intensity and precedes the development of the prurigo lesions. Chronic prurigo can be very burdensome and, as a result, may cause mental disorders such as anxiety and depression, leading to an overall impairment of the quality of life of the affected patients1.

Pathophysiology
Medical conditions leading to chronic itch (≥ 6 weeks duration) and, consequently, to a prolonged scratching behavior, may induce the typical chronic prurigo lesions1. These medical conditions may be of various origins, including dermatological (skin diseases), systemic (malfunction of the inner organs), neurological (diseases of the nervous system) or psychiatric (mental disorders) diseases. In some patients, multiple conditions leading to itch may coexist (multifactorial), while in rare cases, the condition causing the itch remains unknown2.

Diagnostic
When performing diagnostics of chronic prurigo, it is important to identify the underlying cause. A detailed medical history, including comorbidities and co-medications, should be taken and a patient-specific physical examination performed. Laboratory tests may hint towards possible systemic causes for the itch, whereas skin biopsies may help identify possible dermatoses masked by the prurigo lesions.

Therapy
Chronic prurigo is difficult to treat and a combination of topical and systemic agents is often necessary to obtain relief. If possible, the underlying cause for the chronic pruritus should be treated. According to the German Guideline for Chronic Pruritus, topical steroids and pimecrolimus constitute the first-line topical therapy, while UV phototherapy is the systemic option of choice for the symptomatic treatment of chronic prurigo3. Other agents have also shown efficacy in the treatment of chronic prurigo, including capsaicin cream and tacrolimus, as well as gabapentin, pregabalin, cyclosporine A, methotrexate, naltrexone and aprepitant3. It is of note that no agent is currently approved for the treatment of this condition.