How does rosacea progress?

Rosacea is a chronic inflammatory skin condition affecting 2 to 3% of the adult population. More common in women than in men, this initially benign disease can quickly progress to more severe forms if not managed in time, hence the importance of consulting a dermatologist at the onset of the first signs.

1. The emergence of redness and the dilation of blood vessels.

   Most commonly, rosacea initially takes a vascular form, or erythematotelangiectatic. At this stage, it is referred to as couperose. Although it can cause self-consciousness, it is benign and is characterised by a diffuse redness on the face, primarily on the central part (cheeks, nose, chin and sometimes forehead). This redness can be temporary (erythema) or remain permanently (erythrosis). On the other hand, a dilation of the superficial blood vessels can be observed. They then appear red or purplish, showing through the skin. These various symptoms are often accompanied by hot flushes and an increased skin sensitivity. They can weaken the facial skin and cause burning sensations and tingling in patients.

2. The occurrence of papules and pustules.

   Redness may be accompanied by papules and pustules. This advanced form of rosacea is known as papulopustular rosacea and is sometimes mistaken for acne. In the past, it was even referred to as acne rosacea. However, this misleading term has been abandoned for several years now to avoid confusion between these two dermatoses. In addition to redness, individuals with papulopustular rosacea suffer from papules, which are hard, painful areas of thickened skin that are red in colour, and even pustules, indicating an infectious context.

   The occurrence of spots is typically due to the colonisation of sebaceous glands by the parasite Demodex. Naturally present in the epidermis, there are times when this microorganism proliferates excessively, leading to the emergence of inflammatory spots. Indeed, Demodex secretes proteases, enzymes involved in the degradation of proteins that stimulate the activity of PAR-2 receptors (Protease-Activated Receptor), playing a significant role in inflammatory and nociceptive processes. This activation subsequently triggers the release of TNF-α and interleukin-1 (IL-1), pro-inflammatory cytokines. It's worth noting that, like acne, rosacea papulopustular can significantly impact confidence and self-esteem of the affected patient.

3. The thickening of the nose.

   In relatively rare cases, papulopustular rosacea or telangiectasia can progress to a hypertrophic form and cause a rhinophyma. This is characterised by a slow and progressive hypertrophy of the sebaceous glands and connective tissue of the distal part of the nose. The latter appears deformed and relatively red with visible vessels on the surface. Unlike the initial forms of rosacea, rhinophyma predominantly affects men. Causing significant aesthetic damage, this form of rosacea can be quite challenging to live with.

   The mechanisms behind the progression of mild rosacea to rhinophyma are still poorly understood. A hormonal influence is suspected, with some researchers proposing that 5-alpha reductase, indirectly involved in sebum production, plays a role in the pathogenesis of hypertrophic rosacea. The colonisation of the sebaceous glands in the nose by parasites Demodex could also be a contributing factor.

4. An ocular impairment.

   It is estimated that approximately 30 to 50% of rosacea cases are accompanied by an ocular condition. This does not follow a linear pattern: it develops independently or in parallel with other forms of rosacea. Indeed, it can appear simultaneously at any stage of the dermatosis. The ocular rosacea results in a dry eye, tingling, vision disturbances, increased photosensitivity and sometimes inflammation of the eyelids. It is partly due to a dysfunction of the Meibomian glands, sebaceous glands located in the epidermis of the eyelids.

Rosacea does not always progress in a linear fashion. Indeed, from one individual to another, the symptoms of the disease may appear in a variable order.

• STEINHOFF M. & al. Recent advances in understanding and managing rosacea. F1000Research (2018).

• SEITZMAN G. & al. Ocular rosacea. Current Opinion in Ophthalmology (2020).

• ALI F. & al. Rosacea. British Journal of Hospital Medicine (2021).