Prurigo Nodularis (PN) is a persistent inflammatory skin condition marked by the development of firm, painful nodules on the skin's surface. This disorder leads to significant discomfort and adversely impacts an individual's quality of life. The name derives from medical terms associated with itching and the formation of nodular lesions. This condition is characterized by hard, itchy nodules that emerge on the skin, resulting in considerable distress and negatively influencing overall well-being.

Prurigo nodularis (PN) can develop at any age, although it is predominantly observed in adults. Research indicates that this condition often occurs in individuals with a background of atopic diseases, such as eczema, asthma, or hay fever, although the exact prevalence remains unclear. The primary symptom of PN, arguably its most distinguishing feature, is intense itching. This pruritus can be persistent, and scratching typically fails to provide relief; it is frequently described as disproportionate to the visible skin lesions. Itching may lead to sleep disturbances, mainly as it intensifies at night (Zeidler, Yosipovitch, & Ständer, 2018). The principal clinical manifestation of prurigo nodularis is the appearance of multiple hard, rough nodules or lumps on the skin. These nodules are scattered across the body and vary in size from 1 to 3 cm, with the arms and legs being the most affected areas. However, as Zeidler, Yosipovitch, and Ständer (2018) noted, they can also be found on the trunk.

Skin nodules of this nature generally present with a central warty or crusted surface, exhibiting a round or polygonal shape, symmetry, and hyperpigmentation. Evidence of excoriation may be observed on the underlying skin due to frequent scratching. Persistent picking and scratching of these nodules can occasionally lead to ulcers or open sores (Mollanazar, Leahy, & Stockfleth, 2020). Additionally, alterations in skin appearance are a notable feature of prurigo nodularis. Some individuals may notice a shift in skin tone, with affected areas becoming either lighter (hypopigmentation) or darker (hyperpigmentation). Such changes in skin colour are considered normal, even after treatment of the nodules and a reduction in pruritus (Zeidler, Yosipovitch, & Ständer, 2018).

Furthermore, many individuals with prurigo nodularis exhibit signs of lichenification, characterized by skin thickening resulting from continuous rubbing or scratching. This condition causes the skin to appear thick, leathery and hardened (Mollanazar, Leahy, & Stockfleth, 2020). These complications can significantly impact the quality of life of individuals with Prurigo Nodularis.

The diagnosis and management of Prurigo Nodularis present significant challenges owing to the diverse range of potential underlying causes and associated medical conditions, which may include neurological, dermatological, and systemic disorders. Primarily, Prurigo Nodularis is linked to atopic dermatitis, a prevalent chronic inflammatory skin condition characterized by dry skin and relentless itching. Notably, over 80% of patients with Prurigo Nodularis have a history of atopic dermatitis, indicating a possible relationship between these two disorders (Sugita et al., 2019). Additionally, systemic diseases represent another significant contributing factor to the development of Prurigo Nodularis. Conditions such as renal disease, liver disease, HIV, and cancer may provoke the onset of Prurigo Nodularis due to the increased inflammatory response elicited by these illnesses within the body (Carrascosa et al., 2019; Zeidler et al., 2020).

Prurigo Nodularis may arise as a complication associated with various dermatological disorders, such as lichen planus and bullous pemphigoid. These conditions, akin to autoimmune diseases, can amplify the skin's inflammatory response to external factors, potentially leading to the development of PN (Kazandjieva & Tsankov, 2017). Additionally, the immunosuppressive effects of HIV can trigger Prurigo Nodularis, as it is linked to several immunological disorders. Furthermore, Prurigo Nodularis has been associated with psychological conditions, including anxiety and depression. Such mental health issues may exacerbate the itch-scratch cycle, thereby worsening the condition and possibly facilitating the onset of PN (Kim et al., 2019). While Prurigo Nodularis has identifiable causes and associated conditions, it is crucial to recognize that it can also manifest idiopathically, with no discernible origin. This aspect complicates the diagnostic process for this condition.

Treatment for Prurigo Nodularis begins with an accurate diagnosis, necessitating a comprehensive assessment of the patient's medical history and a physical examination. This thorough evaluation is crucial, as conditions such as dermatitis herpetiformis, hypertrophic lichen planus, and cutaneous T-cell lymphoma may be incorrectly identified as Prurigo Nodularis. Once a definitive diagnosis is established, the initial phase of treatment primarily focuses on alleviating the patient's persistent itching. Temporary relief can be achieved through topical corticosteroids and lidocaine-containing numbing creams. Additionally, emollients like petroleum jelly can be beneficial, as they hydrate dry skin and create a protective barrier. For patients who do not respond adequately to topical treatments, systemic medications such as antihistamines may be considered. Furthermore, while antidepressants can assist in managing the discomfort associated with scratch lesions, they may also contribute to reducing itching.

An alternative treatment option is phototherapy, commonly referred to as light therapy, which is particularly beneficial for individuals with extensive prurigo nodularis (PN). Ultraviolet B (UVB) rays may alleviate irritation and facilitate the healing of existing nodules. While generally considered safe, excessive exposure to UV radiation can lead to skin damage; therefore, this treatment must be administered under the guidance of a healthcare professional. Recently, immunomodulatory medications have garnered attention for their potential efficacy in treating PN. Certain drugs, such as sarilumab, modify immune system responses, which may play a role in the development of PN. However, a qualified physician must carefully monitor their application due to the possibility of adverse effects. The potential side effects of these treatments are [specific side effects], and it is important to discuss these with your healthcare provider before starting any treatment.

Integrating treatment with patient education is essential to break the 'itch-scratch cycle.' This cycle contributes to developing new nodules, thereby sustaining the condition. Cognitive-behavioural therapy, a type of psychotherapy that helps patients understand the thoughts and feelings that influence their behaviours, can assist in alleviating post-natal depression by reducing the compulsion to scratch. In summary, effective management of Prurigo Nodularis necessitates a holistic strategy that provides symptomatic relief and addresses any underlying health issues. Although the path may be lengthy, comprehensive diagnostic and therapeutic interventions can significantly enhance the quality of life for individuals suffering from this chronic skin disorder, offering hope for a better future.

Photo: Atopic Dermatitis – Clinician