Dandruff Causes
Dandruff causes are commonly a yeast like fungus called Pityrosporum ovale (P. ovale). As the fungus requires fat to grow, it is most common in areas with many sebaceous glands: on the scalp, face and upper part of the body. When the fungus grows too rapidly, the natural renewal of cells is disturbed and dandruff appears with itching (a similar process may also occur with other fungi or bacteria).For the majority of people , this fungus causes no harmful effects. However, when triggered by certain changes in climate, hormonal or stress levels, the P.ovale fungus tends to concentrate on the scalp for a very good reason - the scalp is where the largest concentration of sebaceous glands can be found. These are the glands that produce your skin's natural oil, called sebum, which contributes to the growth of the P. ovale fungus.
As the fungus grows in size and numbers, it causes increased skin irritation and accelerates the rate at which old skin cells are shed and replaced. The result: dandruff.
Dandruff is usually limited to the scalp and typical symptoms include white or gray flakes and mild skin irritation.
Severe dandruff, or seborrheic dermatitis (seborrhea), is most often found on the scalp but can also appear in the area around the eyebrows, cheeks, behind ears or on the chest. Seborrhea is usually recognized by the appearance of oily yellow flakes and moist red patches on the scalp
The spectrum of dandruff is difficult to define because it blurs with seborrhoeic dermatitis and some other scaly conditions. The inflammation and extension of scaling outside the scalp exclude the diagnosis of dandruff 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 dandruff, where the inflammation is minimal and remain subclinical.
Histological examination reveals the scattered presence of lymphoid cells and squirting capillaries in the papillary dermis with hints of spongiosis and focal parakeratosis.
Seasonal changes, stress, and immuno-suppression seem to affect seborrheic dermatitis and are cited as possible causes of dandruff.