The physical mechanisms behind flushing, the lifestyles of Demodex mites and proper skin care were among the rosacea-related topics covered at the recent 72nd annual meeting of the American Academy of Dermatology in Denver.

Dr. Frank C. Powell, consulting dermatologist at Mater Misericordiae Hospital in Dublin, Ireland, and a member of the National Rosacea Society's Medical Advisory Board, reviewed some of the many diseases and skin conditions whose symptoms are often mistaken for those of rosacea, such as lupus, psoriasis and contact dermatitis.  He noted, for example, that the bulbous red nose associated with subtype 3 (phymatous) rosacea may also be linked to anything from cutaneous tuberculosis to sarcoid or carcinoma, underlining the need for careful diagnosis.

Dr. Síona Ní Raghallaigh, clinical research fellow at the Charles Institute of Dermatology at the University College Dublin School of Medicine, and Dr. Martin Steinhoff, director of the Charles Institute and an NRS research grant recipient, discussed the differences between blushing and facial erythema (redness).  This included the biological and psychological aspects of flushing and its potential transition into the persistent redness of subtype 1 (erythematotelangiectatic) rosacea.

Dr. Steinhoff noted that the skin of the face is one of the only places on the body where the sympathetic, parasympathetic and sensory nervous systems all play a role, and can influence and amplify each other's effects.  This may create a complex cycle of inflammation through multiple mechanisms, which may explain why some cases of rosacea can be resistant to treatment.  He further noted that the vascular system may also be involved, where blood vessel formation triggered by repeated flushing can result in severe persistent redness.

Dr. Powell provided an overview of Demodex mites and the potential involvement of these microscopic scavengers in rosacea.  He pointed out that the mites are most plentiful in the same regions of the face that are most commonly affected by rosacea – the cheeks, nose, chin and forehead. Moreover, while all humans have Demodex on their skin, in rosacea sufferers the quantity of mites has been found to be much higher.¹

“The presence of Demodex is likely to confer some sort of benefit on us, because human physiology is such that we wouldn’t tolerate something like this unless there was something to be gained for us,” he said.  Whatever benefit that might be, in rosacea patients something causes the mites to proliferate, possibly triggering an inflammatory response. Large quantities of mites have been found in biopsies of rosacea papules and pustules, leading Dr. Powell to wonder whether the papules and pustules might not be “gravestones to dead Demodex.”

In a later session, Dr. Guy Webster, clinical professor of dermatology at Thomas Jefferson Medical School, delivered an update of new research and treatments for rosacea. He stressed that since the skin of rosacea patients is defective, stinging and burning are common early side effects of topical therapy, but that as the disorder's symptoms improve, the skin itself becomes healthier. “Treatment should not just be ‘Take this drug’; it should be ‘Take this drug and help the skin get better,’” he said.

Dr. Webster also noted that while rosacea is often thought of as a fair-skin disease, it occurs with significant frequency in darker skin as well.  “The index of suspicion is low, but darker skin may mask redness,” he said.  Doctors should watch for signs such as irritable skin, stinging, facial warmth and ocular rosacea in order to make a diagnosis.

Reference:

1. Forton FMN. Papulopustular rosacea, skin immunity and Demodex: pityriasis folliculorum as a missing link. J Eur Acad Dermatol Venereol 2012;26:19-28.