The cause is unclear but believed to involve a number of genetic and environmental factors. As the skin layers continually replace themselves, cells are pushed outward where they die and flake off. For most individuals, these flakes of skin are too small to be visible. However, certain conditions cause cell turnover to be unusually rapid, especially in the scalp. It is hypothesized that for people with<unk> , skin cells may mature and be shed in 2–7 days, as opposed to around a month in people without<unk> . The result is that dead skin cells are shed in large, oily clumps, which appear as white or grayish flakes on the scalp, skin and clothes. According to one study,<unk>  has been shown to be possibly the result of three factors: # Skin oil, commonly referred to as sebum or sebaceous secretions # The metabolic by-products of skin micro-organisms (most specifically Malassezia yeasts) # Individual susceptibility and allergy sensitivity. Microorganisms Older literature cites the fungus Malassezia furfur (previously known as Pityrosporum ovale) as the cause of<unk> . While this species does occur naturally on the skin surface of people both with and without<unk> , in 2007, it was discovered that the responsible agent is a scalp specific fungus, Malassezia globosa, that metabolizes triglycerides present in sebum by the expression of lipase, resulting in a lipid byproduct: oleic acid. During<unk> , the levels of Malassezia increase by 1.5 to 2 times its normal level. Oleic acid penetrates the top layer of the epidermis, the stratum corneum, and evokes an inflammatory response in susceptible people which disturbs homeostasis and results in erratic cleavage of stratum corneum cells. Seborrhoeic dermatitis In seborrhoeic dermatitis, redness and itching frequently occur around the folds of the nose and eyebrow areas, not just the scalp. Dry, thick, well-defined lesions consisting of large, silvery scales may be traced to the less common condition of scalp psoriasis. Inflammation can be characterized by redness, heat, pain or swelling, and can cause sensitivity. Inflammation and extension of scaling outside the scalp exclude the diagnosis of<unk>  from seborrhoeic dermatitis. However, many reports suggest a clear link between the two clinical entities - the mildest form of the clinical presentation of seborrhoeic dermatitis as<unk> , where the inflammation is minimal and remain subclinical. Seasonal changes, stress, and immunosuppression seem to affect seborrheic dermatitis.
Dandruff
Psoriasis
Sequela
Dermatitis
Crepitus
Tinea capitis
Papular eruption of blacks
Bradyphrenia