Seborrhoeic dermatitis: benign, embarrasing and persistent
Although this condition is not serious, it is most often chronic, and it greatly deteriorates the quality of life of those who are affected.
Seborrhoeic dermatitis is a common skin condition affecting from 3% up to 10% of a given population. The non-inflammatory variant, better known as dandruff, affects up to 50% of that same population! It manifests mostly on the scalp and the face, and ranges from mild irritation to heavy inflammation and skin flaking. Due to its non-life threatening nature and difficult treatment, only a handful of research has been done and those affected are mostly left to their own devices.
Source of discomfort
Seborrhoeic dermatitis is often inaccurately referred to as seborrhoea. While it is connected to the sebaceous gland, it doesn't evolve into acne or inflamed pimples, often associated with seborrhoea. The sebaceous gland is a microscopic gland in the skin that secretes an oily or waxy matter called sebum, lubricating the hair and the skin of mammals. As the name suggests, seborrhoeic dermatitis is the inflammation of the sebaceous glands and the surrounding tissue. The symptoms appear gradually between the age of 25 and 70, and usually start with flaky skin and scalp, becoming progressively worse and including redness, hair loss, itching, soreness, patchy thick crusts on the scalp and yellowish to reddish scaly pimples along the hairline and skin folds. Besides the scalp and the face, it can occur anywhere on the face, behind the ears, upper chest and back, and in areas where skin folds. Besides pain and discomfort, it is a significant source of quality of life impairment, especially in young adults, with scalp flakes and red and flaky skin emphasizing self awareness or anxiety. The social aspect of this condition is so prominent, it has been ranked third biggest quality of life impairment, behind atopic and contact dermatitis.
Figure 1: schematic view of hair folicle and sebatic gland. By National Institute of Health.
Figure 2: An example of seborrhoeic dermatitis between the nose and mouth. By Roymishali - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=27267929
No research done up until present day has fully clarified the exact cause of seborrhoeic dermatitis. Several internal factors play a role, including the exact composition of skin lipids, hormone excretion and the state of immune system. This also means that the conditions becomes aggravated by illness, stress, fatigue, reduction of health and change of season. In all cases, it is accompanied by an external factor – the presence of Malassezia fungi. Other external factors include low humidity and low temperature.
The Malassezia fungi is a common inhabitant of the outer layer of human skin, but in conjunction with other factors it can cause inflammatory reactions due to its production of fatty acids. It feeds in the sebum-rich areas of the human skin, and its overpopulation is considered the main cause of the condition.
Short term treatment and remedies
While both anti-fungal and anti-inflammatory treatments show short-term results, no cure has yet been discovered, most probably due to its multifactorial nature. Medication against the Malassezia fungus has shown some results by reducing its quantity, but the condition relapses after treatment. Skin preparations containing ketoconazole, bifonazole and selenium sulfide have shown to be the best option.
Topical corticosteroids are effective in short-term soothing of the skin, but are never perscribed as a long-term option. These are best taken by consulting a doctor in case of an especially harsh outbreak.
If the effected area is itching constantly, antihistamines can also be prescribed.
Long-term problems and solutions
The chronic nature of this condition means that any aggressive treatment can't be taken indefinitely, no matter how effective it is. The disruptive nature of antifungal remedies, as well as immunomodulating effects of corticosteroides cumulatively tend to harm both the affected skin and the surrounding tissues.
For best long-term results, non-aggressive methods must be applied. This includes the removal of excess sebum, especially in people with oily skin. This is best done with a mild exfoliant, but a more thorough hygiene of the affected area will also help. This will limit the habitat and the feeding ground of the Malassezia fungi. It will inevitably dry out the skin, and as stated previously, low humidity is one of the external factors in skin flaking. In that regard, skin moisturizing is advised, especially if the skin is tight, flaky or tender after washing. Face cremes with ingredients similar to sebum (oily or fatty) aren't advised.
The affected scalp is best washed regularly, at least every second day, with a mild shampoo without any additives. This helps remove the already present flakes and reduces the amount of new ones generated.
More aggressive treatments are to be saved for outbreaks, as for example during changing of seasons.
Nothing new on the horizon
Although seborrhoeic dermatitis affects a significant portion of the population, it is neglected in research due to its non-lethal nature and complexity of origin. If not treated, it can lead to secondary bacterial infections due to alteration of the skin, self esteem deterioration and frustration. The most recent research, although insufficient, indicates that the main problem is the disruption of skin cell adhesion in people with seborrhoeic dermatitis. This allows other factors, such as Malassezia fungi, to grow more freely and make the disease even worse. It is not yet possible to find a definitive cure, but better skin preparations are becoming available every year.
1. Sampogna F, Linder D, Piaserico S, Altomare G, Bortune M, Calzavara-Pinton P, Vedove CD, Girolomoni G, Peserico A, Sala R, Abeni D. Quality of life assessment of patients with scalp dermatitis using the Italian version of the Scalpdex. Acta Derm Venereol. 2014 Jul;94(4):411-4.
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