What is rosacea?
Rosacea is a chronic rash involving the central face that most often affects those aged 30 to 60. It is common in those with fair skin, blue eyes and Celtic origins. It may be transient, recurrent or persistent and is characterised by its colour, red.
Although once known as “acne rosacea”, this is incorrect, as it is unrelated to acne.
What is the cause of rosacea?
There are several theories regarding the cause of rosacea, including genetic, environmental, vascular and inflammatory factors. Skin damage due to chronic exposure to ultraviolet radiation plays a part.
The skin’s innate immune response appears to be important, as high concentrations of antimicrobial peptides such as cathelicidins have been observed in rosacea. Cathelicidins are part of the skin’s normal defence against microbes.
Cathelicidins promote infiltration of neutrophils in the dermis and dilation of blood vessels. Neutrophils release nitric acid also promoting vasodilation. Fluid leaks out of these dilated blood vessels causing swelling (oedema); and proinflammatory cytokines leak into the dermis, increasing the inflammation.
Matrix metalloproteinases (MMPs) such as collagenase and elastase also appear important in rosacea. These enzymes remodel normal tissue and help in wound healing and production of blood vessels (angiogenesis). But in rosacea, they are in high concentration and may contribute to cutaneous inflammation and thickened, hardened skin. MMPs may also activate cathelicidins contributing to inflammation.
Hair follicle mites (Demodex folliculorum) are sometimes observed within rosacea papules but their role is unclear.
An increased incidence of rosacea has been reported in those who carry the stomach bacterium Helicobacter pylori, but most dermatologists do not believe it to be the cause of rosacea.
Rosacea may be aggravated by facial creams or oils, and especially by topical steroids.
What are the clinical features of rosacea?
Rosacea results in red spots (papules) and sometimes pustules. They are dome-shaped rather than pointed and unlike acne, there are no blackheads, whiteheads or nodules. Rosacea may also result in red areas, scaling (rosacea dermatitis) and swelling.
Characteristics of rosacea include:
Frequent blushing or flushing
A red face due to persistent redness and/or prominent blood vessels – telangiectasia (the first stage or erythematotelangiectatic rosacea)
Red papules and pustules on the nose, forehead, cheeks and chin often follow (inflammatory or papulopustular rosacea); rarely, the trunk and upper limbs may also be affected
Dry and flaky facial skin
Aggravation by sun exposure and hot and spicy food or drink (anything that reddens the face)
Sensitive skin: burning and stinging, especially in reaction to make-up, sunscreens and other facial creams
Red, sore or gritty eyelid margins including papules and styes (posterior blepharitis), and sore or tired eyes (conjunctivitis, keratitis, episcleritis) – ocular rosacea
Enlarged unshapely nose with prominent pores (sebaceous hyperplasia) and fibrous thickening – rhinophyma
Firm swelling of other facial areas including the eyelids – blepharophyma
Persistent redness and swelling or solid oedema of the upper face due to lymphatic obstruction – Morbihan disease
What is the differential diagnosis of rosacea?
Rosacea may occasionally be confused with or accompanied by other facial rashes including:
Irritant contact dermatitis
How is rosacea diagnosed?
In most cases, no investigations are required and the diagnosis of rosacea is made clinically. Occasionally a skin biopsy is performed, which shows chronic inflammation and vascular changes.