The<unk>  of seborrhoeic<unk>  has not been fully clarified. In addition to the presence of Malassezia, genetic, environmental, hormonal, and immune-system factors are necessary for and/or modulate the expression of seborrhoeic<unk> . The condition may be aggravated by illness, psychological stress, fatigue, sleep deprivation, change of season, and reduced general health. In children and babies, excessive vitamin A intake or issues with Δ6-desaturase enzymes have been correlated with increased risk. Seborrhoeic<unk> -like eruptions are also associated with vitamin B6 deficiency. Those with immunodeficiency (especially infection with HIV) and with neurological disorders such as Parkinson's 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<unk> . 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<unk>  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<unk> , 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<unk> . 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<unk> . Eunuchs, owing to their low androgen levels and small sebaceous glands, do not develop seborrheic<unk> .
medical cause of Dermatitis
symptom of Psoriasis
symptom of Rosacea
medical cause of Dermatophytosis
symptom of Herpes labialis
symptom of Stevens–Johnson syndrome
symptom of Epidermolysis bullosa
medical cause of Stye