Prurigo nodularis (PN) is a skin disease characterized by pruritic (itchy) nodules which usually appear on the arms or legs. Patients often present with multiple excoriated lesions caused by scratching. PN is also known as Hyde prurigo nodularis, Picker‘s nodules, atypical nodular form of neurodermatitis circumscripta, lichen corneus obtususLichen simplex chronicus is a distinct clinical entity.
Signs and symptoms
- Nodules are discrete, generally symmetric, hyperpigmented or purpuric, and firm. They are greater than 0.5 cm in both width and depth (as opposed to papules which are less than 0.5 cm). They can appear on any part of the body, but generally begin on the arms and legs.
- Excoriated lesions are often flat, umbilicated, or have a crusted top.
- Nodules may appear to begin in the hair follicles.
- Nodule pattern may be follicular.
- In true prurigo nodularis, a nodule forms before any itching begins. Typically, these nodules are extremely pruritic and are alleviated only by steroids.
Diagnosis is based on visual examination and the presence of itching. A skin biopsy is often performed to exclude other diseases. Lesion biopsies will typically show a high level of eosinophils in PN. A culture of at least one lesion will rule out staphylococcus infection, which has been significantly linked to atopic dermatitis.