Seborrhoeic dermatitis, sometimes inaccurately referred to as seborrhoea, is a long-term skin disorder. Symptoms include red, scaly, greasy, itchy, and inflamed skin. Areas of the skin rich in oil-producing glands are often affected including the scalp, face, and chest. It can result in social or self-esteem problems. In babies, when the scalp is primarily involved, it is called cradle cap. Dandruff is a milder form of the condition without inflammation.The cause is unclear but believed to involve a number of genetic and environmental factors. Risk factors include poor immune function, Parkinsons disease, and alcoholic pancreatitis. The condition may worsen with stress or during the winter. The Malassezia yeast is believed to play a role. It is not a result of poor hygiene. Diagnosis is typically based on the symptoms. The condition is not contagious.The typical treatment is antifungal cream and anti-inflammatory agents. Specifically, ketoconazole or ciclopirox are effective. It is unclear if other antifungals, such as miconazole, are equally effective as they have been poorly studied. Other options may include salicylic acid, coal tar, benzoyl peroxide, and phototherapy.The condition is most common in infants within the first 3 months or in adults aged 30 to 70 years. In adults between 1% and 10% of people are affected. Males are more often affected than females. Up to 70% of babies may be affected at some point in time. Signs and symptoms
Seborrhoeic dermatitis symptoms appear gradually, and usually the first signs are flaky skin and scalp.
In children and babies, excessive vitamin A intake or issues with Δ6-desaturase enzymes have been correlated with increased risk. Seborrhoeic dermatitis-like eruptions are also associated with vitamin B6 deficiency. Those with immunodeficiency (especially infection with HIV) and with neurological disorders such as Parkinsons disease (for which the condition is an autonomic sign) and stroke are particularly prone to it. Climate
Low humidity and low temperature are responsible for high frequency of seborrheic dermatitis. Fungi
The condition is thought to be due to a local inflammatory response to over-colonization by Malassezia fungi species in sebum-producing skin areas including the scalp, face, chest, back, underarms, and groin. This is based on observations of high counts of Malassezia species in skin affected by seborrhoeic dermatitis and on the effectiveness of antifungals in treating the condition. Such species of Malassezia include M. furfur (formerly Pityrosporum ovale), M. globosa, M. restricta, M. sympodialis, and M. slooffiae. Although Malassezia appears to be the central predisposing factor in seborrhoeic dermatitis, it is thought that other factors are necessary for the presence of Malassezia to result in the pathology characteristic of the condition. This is based on the fact that summer growth of Malassezia in the skin alone does not result in seborrhoeic dermatitis. Besides antifungals, the effectiveness of anti-inflammatory drugs, which reduce inflammation, and antiandrogens, which reduce sebum production, provide further insights into the pathophysiology of seborrhoeic dermatitis. Eunuchs, owing to their low androgen levels and small sebaceous glands, do not develop seborrheic dermatitis.