What is the pruritus and its importance in dermatosis?

Pruritus is a symptom that can be present in dermatosis, but it is not always related to skin alterations.
Pruritus can be the only manifestation of a systemic disease or a psychosomatic disorder.
Histamine is the only mediator chemical involved in the genesis of pruritus.
Antihistamines are always effective in the treatment of pruritus.