Rosacea is a chronic inflammatory skin condition that primarily affects the face, characterized by redness and visible blood vessels. It frequently presents with recurrent flushing and persistent erythema, sometimes accompanied by inflammatory bumps or pus-filled lesions (papules and pustules). These symptoms result from neurovascular dysregulation and immune system activation within the skin. Rosacea is generally a progressive condition, though its severity and specific symptoms vary greatly among affected individuals.
Common Areas of Rosacea Presentation
The signs of rosacea typically begin in the center of the face, following a symmetrical distribution. Areas most commonly involved include the convex surfaces, such as the nose, cheeks, chin, and central forehead. Persistent redness, known as fixed centrofacial erythema, is the defining feature. The severity of this redness often fluctuates, intensifying with exposure to environmental or dietary triggers like heat, spicy foods, or emotional stress.
Visible, small blood vessels (telangiectasias) frequently appear on the cheeks and nose, overlaying the background erythema. Papules and pustules, when present, also concentrate in this central facial zone. This pattern distinguishes rosacea from acne due to the absence of comedones (blackheads and whiteheads).
The Nasolabial Fold: A Characteristic Sparing
A specific and clinically useful feature of rosacea is the characteristic sparing of the nasolabial folds (NLF). The NLF are the deep creases that run from the outer edge of the nose down to the corners of the mouth. In a patient with rosacea, the intense redness and inflammatory lesions on the cheeks and chin often stop abruptly at the margin of this crease, leaving the skin within the fold unaffected.
This lack of involvement is not fully understood but is thought to be related to anatomical or micro-environmental differences in the skin of the crease versus adjacent convex facial areas. Rosacea pathology involves inflammation around the pilosebaceous units (hair follicles and oil glands) and dysregulation of superficial blood vessels. The NLF may have a different density or type of these structures compared to the cheek.
This sparing creates a visual contrast, where the inflamed central face appears to frame the unaffected skin of the folds. Observing this precise pattern—central facial inflammation with a clean, unaffected NLF—serves as a strong diagnostic indicator for rosacea. The preservation of the crease is a reliable sign that helps narrow down the list of potential skin conditions.
Conditions That Involve the Nasolabial Folds
The sparing of the NLF in rosacea is important because it helps distinguish the condition from other common facial rashes that frequently involve the folds.
Seborrheic Dermatitis
Seborrheic dermatitis often presents with greasy, yellowish scaling and redness highly concentrated in the NLF, the eyebrows, and the sides of the nose. Unlike the papules and pustules of rosacea, seborrheic dermatitis is characterized by a flaky scale.
Contact Dermatitis
Contact dermatitis is an inflammatory reaction to an external irritant or allergen. Its distribution relates directly to where the offending substance was applied, and this often includes the creases of the NLF. This condition is usually intensely itchy, a symptom that is less prominent in rosacea. A rash that extends into the folds is a strong clue that the diagnosis may not be rosacea, prompting examination for alternative conditions.