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Rosacea is a chronic inflammatory facial skin disease characterised by flare-ups and periods of remission. The exact aetiology of rosacea is not known, but its origin is thought to be multifactorial .
The epidemiology of rosacea has not been extensively studied. Its prevalence is uncertain and ranges from 0.09 to 10% depending on the populations studied [1, 2].
Rosacea essentially affects individuals aged between 30 and 50 years, but there have been cases reported in subjects younger than 20 years.
The condition predominantly affects women with lesions occurring essentially on the cheeks and chin; in men, the lesions, which appear more severe, occur essentially on the nose. Rosacea may affect any skin type, but is more frequent in subjects with fair skin. A family history of the condition is observed in about 30 to 40% of cases [1, 3].
The lesions may be very obvious and have a marked impact on quality of life.
Rosacea is frequently associated with alcoholism and patients may present with stigmatizing rhinophyma, which both cause psychological suffering .
Rosacea is a central-facial disease that, for the most part, symmetrically affects the convex areas of the face (chin, nose, cheeks). No lesions are observed in the areas around the eyes and mouth. The lesions are generally symmetrical but may occur on only one side.
Patients with facial lesions should undergo a complete physical examination as they may also present with extrafacial lesions, although their exact prevalence is unknown. Extrafacial lesions may affect the hairless area of the scalp in men, the neck, and the presternal and epigastric regions, but only exceptionally the limbs and palms. Clinically and histologically, they are no different to facial lesions .
Rosacea lesions are characteristically polymorphic and they may occur isolatedly or together. They include transient erythema, flushing, non-transient erythema, papulopustules (without comedones), telangiectasia, hypertrophic lesions, etc. Patients may present with ocular lesions together with skin lesions and various other symptoms. A standard grading system was developed by the National Rosacea Society (NRS) in 2002 to help with the treatment of patients and the study of rosacea [5, 6].
1.1 - PATHOPHYSIOGY [7, 15]
The pathophysiology of rosacea is complex and poorly understood. It implicates vascular, inflammatory and immunological factors.
The condition is thought to be related to abnormal blood flow in the facial vein resulting in less effective facial homeothermy. Transient flushing (favoured by sudden changes in temperature), primary vascular lesions (telangiectasia and erythema) and histological lesions in vascular tissues all corroborate the vascular hypothesis.
UV radiation is thought to contribute to the release of free radicals responsible for the vascular lesions. Demodex folliculorum, a saprophytic parasite, plays a role in the inflammatory phenomena observed in patients with rosacea. The lesions are provoked by an immune response against Demodex proteins or the bacteria (Bacillus oleronius) found inside the mites. Patients with rosacea carry Demodex mites more frequently than healthy patients and mite density in affected areas is higher than on the healthy skin of the same subject.
It has been suggested that changes in innate immune reactions involving specific epidermal proteins (cathelicidins) directed against numerous microorganisms are implicated in the development of the condition. The proteins are split into peptides by proteases (kallikrein 5) present in too great quantities in the epidermis. The peptides then generate an inflammatory reaction implicating interleukin-8. Activation of the proteinases appears to depend on several factors and at this point, it is not known if the abnormal innate immune reaction marks the beginning of inflammation or if it is just a mechanism of the inflammation.
The implication of Helicobacter pylori in rosacea has not been clearly established. A study has demonstrated improvement in rosacea lesions in some patients treated with rifampicin for gastrointestinal microbial proliferation.
Currently, gastrointestinal investigations are limited to patients presenting with gastrointestinal symptoms evocative of a peptic ulcer.
1.2 - PROGRESSION AND COMPLICATIONS
Rosacea progresses in flare-ups and may regress spontaneously after several years of development. However, the condition most often worsens progressively over the years.
The most severe complications result from ocular rosacea which may precede or follow skin symptoms. Symptoms of ocular rosacea include dry eyes, conjunctivitis, blepharitis, corneal-scleral ulcers and keratitis, which may lead to blindness.
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