Rosacea is a common chronic cutaneous disease primarily of the facial skin. It is common in the third and fourth decade of life, peaking at the age of 40 and 50 years. The causes of rosacea are still not identified. Among others an important factor seems to be a microcirculatory disturbance. The early stage rosacea is characterised by persistent erythema and teleangiectasia predominantly of the cheeks frequently followed by papules and papulopustules. Later, there may occur diffuse hyperplasia of connective tissue and sebaceous glands. This can cause a hypertrophy of the nose, a so called rhinophyma. Rosacea occurs in stages and may affect the eyes, most commonly resulting in blepharitis and conjunctivitis. Also other parts beside the face such as retro auricular areas, neck, chest, back and the scalp may be affected. The clinical appearance can be similar to acne, but in contrast rosacea is not a primary follicular disease.
Rosecea:
The precise cause of rosacea is still unknown; a multifactorial cause is most likely. Over the years, many suspected but unconfirmed causes have been reported. These include factors like genetic predisposition, heredity, dyspepsia with gastric hypochlorhydria, inflammatory bowel disease and infestation with the bacterium Helicobacter pylori, seborrhoea, Demodex folliculorum mites, endocrine diseases, vitamin deficiencies, microcirculatory disturbances, hepatopathy or psychogenic factors.
• Demodex folliculorum:
Demodex folliculorum mites are much more frequent in rosacea patients then in control groups. Early vascular and connective tissue changes probably create a favourable setting for a secondary proliferation. Demodex folliculorum may represent an important cofactor especially in papulopustular rosacea, in which a delayed hypersensitivity reaction is suspected, but it is not the cause of rosacea.
• Psychogenic factors:
Psychological stress may influence rosacea but it is not its primary cause.
• Flushing and vascular pathogenesis:
Rosacea patients are predisposed to flushing and blushing. Several triggers are known like heat, cold, ultraviolet radiation, emotions, alcohol, spices or hot drinks. Flushing after drinking hot water, coffee or tea is due to pharyngeal warming of the blood per fusing the hypothalamus by counter current heat exchange involving the jugular vein and carotid arteries. Hyperthermia in rosacea patients causes a decrease of blood shunting from the face to the brain. The dysfunction seems to be a microcirculatory disturbance of the facial angular veins (Vena facialis sive angularis) which are involved in the vascular cooling system of the brain. This may lead to a venous congestion and failure of thermoregulation. The facial angular veins drain the parts of the face which are mostly affected by rosacea including the conjunctiva. This could explain the frequent involvement of the eyes. A vascular dysfunction could also be the reason for the increase of migraine headaches in rosacea patients. Rosacea skin reacts normal to various vasoactive chemicals like caffeine or to chemomediators such as epinephrine, acetylcholine or histamine. Vasoactive intestinal peptide (VIP) and its receptor are important for blood flow regulation. An increased concentration of the receptor was found in rhinophyma and therefore it is suggested that this may contribute to vascular and dermal alterations in rosacea.
• Genetic:
The evidence for a genetic predisposition in rosacea is growing. 30-40% of patients with rosacea have a relative with this condition.
• Seborrhoea:
Experimental studies did not approve an association between rosacea and seborrhoea. Due to the localisation and the effectiveness of isotretinoin some authors suspect that seborrhoea is a factor of rosacea, though sebum production is often not increased in rosacea patients (apart of Rosacea fulminans).
• Light:
Ultraviolet light plays a major role in rosacea development. It affects the dermal connective tissue as well as lymphatic and blood vessels and could contribute to passive vasodilation. Actinically affected skin is a consistent background of rosacea. Photodamage is common in fair-skinned rosacea patients.
• Endocrine Disease:
Increases in rosacea during pregnancy, menses or perimenopausal have been noted.
• Lymphatic system:
Lymphedema is suspected to play a major role especially in the severe form of rhinophyma. A fibrotic dermatitis with many similarities with elephantiasis has been found in rhinophyma patients. Sometimes a chronic facial skin lymph oedema is recognised.
• Medications:
Some drugs such as amiodarone or nitro-glycerine-like drugs (e.g. nifedipine) may affect rosacea through vasodilatation which induces flushing.
• Immunological factors:
Investigations indicate a higher incidence of immune abnormalities like different types of antinuclear antibodies in the blood. Also IgG antibodies to Demodex folliculorum mites were detected in rosacea skin.
• Gastrointestinal disturbances:
An association of gastrointestinal symptoms like gastric hyperchlorhydria, dyspepsia, diarrhoea, constipation or alimentary symptoms and rosacea has been suspected, but there is no strong evidence for any relation.
• Aggravating factors
Aggravating factors are all possible trigger of flushing and blushing. People who suffer from rosacea should avoid these factors.
These factors are:
1. Extreme temperatures like cold or heat (e.g. sauna): Extreme temperatures like cold or especially heat (as in a sauna or while taking a hot bath) cause physiological flushing and may trigger rosacea. So they should be avoided.
2. Ultraviolet radiation: Frequently rosacea is associated with sun-damaged skin (solar elastosis), which seems to be a triggering factor. Hence, especially patients with rosacea should avoid ultraviolet radiation like sun beds.
3. Emotional stress: Emotional stress may induce flushing, which is a precursor of rosacea.
4. Alcoholic beverages: Already small quantities of alcohol induce vasodilatation, which may cause intensive flushing. As flushing is an important trigger rosacea patients should abstain from alcohol.
5. Spiced food induces flushing associated with sweating due to a reflex of the trigeminal nerve. As flushing is an important trigger rosacea patients should not eat spiced food.
6. Hot drinks induce flushing due to the effect of rise in blood temperature. As flushing is an important trigger rosacea patients should avoid hot drinks.
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