Nodular prurigo on a patients head. This condition is characterised by the appearance of very itchy, wart-like bumps, or nodules, on the skin. The bumps occur when the skin has been itched for a long time. Then, the formation of the nodules brings on more severe itching, triggering a cycle that can lead to skin damage (excoriated lesions). The underlying cause of the condition is unknown. Treatments include steroid creams, antihistamines and phototherapy.