​Pathology - Allergic Rhinitis 
This condition is characterized by a Type I (IgE-mediated) acute hypersensitivity reaction to environmental allergens. Patients will often have a personal or family history of other atopic diseases such as asthma or atopic dermatitis. The syndrome is marked by a predisposition to produce IgE antibodies to environmental antigens. As these antigens are filtered by the nasal airways, interaction with surface-bound IgE antibodies on mast cells and basophils triggers a release of preformed mediators and the de novo synthesis of additional mediators, as well as the creation and release of proinflammatory cytokines. Interaction of mediators induces a complicated reaction in target organs, which includes the release of histamine and other stored mediators in the initiation of a complex cascade of actions. Frequent or persistent exposure leads to mucus hypersecretion, IgE production, eosinophilia, and tissue damage. Patients will most usually appear with congestion, clear nasal discharge, pale or bluish nasal mucosa, and possibly infraorbital cyanosis. Nasal, ocular, and/or palate irritation can be present as well.
Extensive rubbing of the nose over an extended period of time can also lead to a characteristic transverse nasal crease.
A positive intracutaneous skin test can provide proof of triggering allergens.