The true cause of prurigo nodularis is unknown, says the National Center for Advancing Translation Services. This is a rare skin condition characterized by hard, crusty and itchy lumps. The condition tends to get severe in the night or when clothes brush against the itchy area, explains the American Osteopathic College of Dermatology. In many cases, the itching stops when a patient scratches the lump until it bleeds.
Prurigo nodules are about 1/2 inch in size with a dry and rough top, states the American Osteopathic College of Dermatology. Scratching results in prurigo nodularis because it leads to thickening of the skin nerves. The more a person scratches the itchy area, the stronger the nerves grow. Factors that worsen the condition include poorly functioning kidneys and liver, mental and nervous problems, and skin conditions such as dermatitis herpetiformis, bullous pemphigoid and eczema.
The treatment for prurigo nodularis is quite challenging, explains National Center for Advancing Translation Services. Doctors try different treatments as there is no single specific treatment that is effective in easing the symptoms. Doctors prescribe steroid creams alongside other milder creams to manage the condition, says the American Osteopathic College of Dermatology. Patients also use antihistamine pills to boost the treatment.