What could cause pickers nodules?

Picking. Pickers nodules, aka prurigo nodularis, may start out as anything causing itching and then the nerves in that area go haywire and the person picks and rubs and continues to manipulate the area, then, thick nodules that have more nerves and sensations grow and the cycle continues. The only way to break the cycle is to not touch these spots alt all. For itching, topical or injected corticosteroid.