Pityriasis (seborrhoeic dermatitis)


 Pityriasis, seborrheic dermatitis or seborrheic eczema is a chronic inflammatory skin disorder that causes dandruff. This is a disease that targets body areas with excess production of sebum from the sebaceous glands; primarily the scalp but can also include the face and centre of chest. The initial stages of seborrheic dermatitis are redness and inflammation of the skin or scalp. This stage is followed by a build-up of dry and itchy scales. A mild form of seborrheic dermatitis of the scalp is known as dandruff, which is much more common. Cradle cap is the name used to describe seborrheic dermatitis in infants younger than three months. It appears on the scalp as well as the nappy area, is not usually itchy and will disappear after a few months. Seborrheic dermatitis though chronic is usually manageable, using treatments and precautions discussed later in this essay.


Seborrheic dermatitis is a condition prompted by a number of factors. Malassezia globosa is a fungus that resides harmlessly on the surface of the skin. This is a yeast that that thrives on sebum. Its overgrowth, which is thought to be prompted by the overproduction of sebum, is believed to cause the inflammation. The yeast affects patients with a low resistance to Malassezia, such as patients with immunodeficiency like HIV or a lack of zinc. Seborrheic dermatitis can also affect patients with nervous system issues like Parkinson’s disease and stroke victims. Stress and fatigue can also be a trigger to the condition.

Seborrheic dermatitis is also thought to be genetic in nature and environmental factors such as cold weather can trigger the condition. Changes occurring during puberty can aggregate the condition, primarily the increase in sebum production that occurs on the face and scalp. Insufficiency of the vitamin B group are also thought to cause seborrheic dermatitis, these are biotin, pyridoxine and riboflavin. Too much intake of vitamin A has also been seen to cause seborrheic dermatitis in children. However, the BAD states that the condition is not related to diet.


Seborrheic dermatitis affects almost 4% of the U.K population according to the British Association of Dermatologists (BAD), Bupa puts this number at 5%. It usually affects adults between 30 and 60 years of age. The BAD also states that the milder form of seborrheic dermatitis (dandruff) can affect almost half of all adults. The condition appears to affect more men than women. In infants the diseases is referred to as cradle cap or infantile seborrhoeic dermatitis but is short-lived. Seborrhoeic dermatitis can start anytime after puberty, possibly due to an increase in sebum production that usually occurs during and after puberty.


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