What clinical manifestation is a common sign of allergic rhinitis?

In the context of allergic rhinitis, a common clinical manifestation is the presence of nasal congestion that can lead to reduced transillumination on the skin over the sinuses. Allergic rhinitis is characterized by inflammation of the nasal mucosa due to exposure to allergens, leading to symptoms such as nasal congestion, runny nose, sneezing, and itching. This inflammation can cause the sinuses to become blocked or filled with fluid, making it difficult for light to pass through during transillumination tests, which is a method used to assess sinus health.

The other answer options are not typical signs of allergic rhinitis. High-grade fever is more commonly associated with infections rather than allergic reactions. Reduced breathing through the mouth can happen due to nasal congestion but isn't a direct clinical sign, while a pinkish nasal discharge is often indicative of an infection rather than allergy. In allergic rhinitis, the nasal discharge is typically clear and watery. Thus, reduced transillumination correlates directly with the symptoms and underlying pathophysiology of allergic rhinitis effectively.