Dandruff

For the album by Ivor Cutler, see Dandruff (album).

Dandruff
Classification and external resources
A microscopic image of human dandruff
ICD-9	690.18
DiseasesDB	11911

Dandruff^[1] (Latin: Pityriasis simplex capillitii^[1]) is the shedding of dead skin cells from the scalp (not to be confused with a dry scalp). Dandruff is sometimes caused by frequent exposure to extreme heat and cold. As it is normal for skin cells to die and flake off, a small amount of flaking is normal and common; about 487,000 cells/cm² get released normally after detergent treatment.^[2] Some people, however, either chronically or as a result of certain triggers, experience an unusually large amount of flaking, up to 800,000 cells/cm², which can also be accompanied by redness and irritation. Most cases of dandruff can be easily treated with specialized shampoos.

Zoomed version of microscopic picture of human dandruff

Dandruff is a common scalp disorder affecting almost half of the population at the pre-pubertal age and of any sex and ethnicity. In some cultures dandruff is considered aesthetically displeasing. It often causes itching. It has been well established that keratinocytes play a key role in the expression and generation of immunological reactions during dandruff formation. The severity of dandruff may fluctuate with season as it often worsens in winter.^[2]

Those affected by dandruff find that it can cause social or self-esteem problems. Treatment may be important for both physiological and psychological reasons.^[3]

Causes

As the epidermal layer continually replaces itself, cells are pushed outward where they eventually die and flake off. In most people, these flakes of skin are too small to be visible. However, certain conditions cause cell turnover to be unusually rapid, especially in the scalp. For people with dandruff, skin cells may mature and be shed in 2–7 days, as opposed to around a month in people without dandruff. The result is that dead skin cells are shed in large, oily clumps, which appear as white or grayish patches on the scalp, skin and clothes.

Malassezia furfur species causes dandruff

Dandruff has been shown to be the result of three required factors:^[4]

1. Skin oil commonly referred to as sebum or sebaceous secretions^[5]
2. The metabolic by-products of skin micro-organisms (most specifically Malassezia yeasts)^{[6][7][8][9][10]}
3. Individual susceptibility

Older literature cites the fungus Malassezia furfur (previously known as Pityrosporum ovale) as the cause of dandruff. While this species does occur naturally on the skin surface of both healthy people and those with dandruff, in 2007 it was discovered that the responsible agent is a scalp specific fungus. During dandruff, the levels of Malassezia increase by 1.5 to 2 times its normal level. Malassezia globosa,^[2][11] that metabolizes triglycerides present in sebum by the expression of lipase, resulting in a lipid byproduct oleic acid (OA). Penetration by OA of the top layer of the epidermis, the stratum corneum, results in an inflammatory response in susceptible persons which disturbs homeostasis and results in erratic cleavage of stratum corneum cells.^[8]

Rarely, dandruff can be a manifestation of an allergic reaction to chemicals in hair gels, sprays, and shampoos, hair oils, or sometimes even dandruff medications like ketoconazole.^{[citation needed]}

There is some evidence that excessive perspiration and climate have significant roles in the pathogenesis of dandruff.^{[citation needed]}

Dandruff composition

Dandruff scale is a cluster of corneocytes, which have retained a large degree of cohesion with one another and detach as such from the surface of the stratum corneum. The size and abundance of scales are heterogeneous from one site to another and over time. Parakeratotic cells often make up part of dandruff. Their numbers are related to the severity of the clinical manifestations, which may also be influenced by seborrhea.^[2]

Seborrhoeic dermatitis

Main article: Seborrhoeic dermatitis

Flaking is a symptom of seborrhoeic dermatitis. Joseph Bark notes that "Redness and itching is actually seborrheic dermatitis, and it frequently occurs around the folds of the nose and the eyebrow areas, not just the scalp." Dry, thick, well-defined lesions consisting of large, silvery scales may be traced to the less common psoriasis of 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.^[5] 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.^[12][13]

Seasonal changes, stress, and immuno-suppression seem to affect seborrheic dermatitis.^[2]

Treatment

Coconut Oil use a combination of ingredients to control dandruff. The pathogenesis of dandruff involves hyperproliferation of keratinocytes, resulting in deregulation of keratinization. The corneocytes clump together, manifesting as large flakes of skin. Essentially, keratolytic agents such as salicylic acid and sulphur loosen the attachments between the corneocytes and allow them to get swiped off.

Regulators of keratinization

Zinc pyrithione (ZPT) heals the scalp by normalizing the epithelial keratinization or sebum production or both. Some studies have shown a significant reduction in the number of yeasts after use of ZPT, which is an antifungal and antibacterial agent.^[14] A study by Warner et al.^[15] demonstrates a dramatic reduction of structural abnormalities found in dandruff with the use of ZPT; the population abundance of Malassezia decreases, parakeratosis gets eliminated and corneocytes lipid inclusions are diminished.^[2]

Steroids

The parakeratotic properties of topical corticosteroids depend on the structure of the agent, the vehicle and the skin onto which it is used. Corticosteroids work via their anti-inflammatory and antiproliferative effects.^[16]

Selenium sulfide

It is believed that selenium sulfide controls dandruff via its anti Malassezia effect rather than by its antiproliferative effect, although it has an effect in reducing cell turnover. It has anti-seborrheic properties as well as cytostatic effect on cells of the epidermal and follicular epithelium. The excessive oiliness after use of this agent has been reported in many patients as adverse drug effec

Imidazole antifungal agents

Imidazole topical antifungals such as ketoconazole act by blocking the biosynthesis of ergosterol, the primary sterol derivative of the fungal cell membrane. Changes in membrane permeability caused by ergosterol depletion are incompatible with fungal growth and survival.^[17]

Ketoconazole is a broad spectrum, antimycotic agent that is active against both Candida and M. furfur . Of all the imidazoles, ketoconazole has become the leading contender among treatment options because of its effectiveness in treating seborrheic dermatitis as well.^[2]

Hydroxypyridones

In contrast to the imidazole antifungals, the hydroxypyridones do not affect sterol biosynthesis; instead they interfere with the active transport of essential macromolecule precursor, cell membrane integrity and the respiratory process of cells. Ciclopirox is widely used as an AD agent in most preparations.^[18]

Water temperature

Like other skin conditions, hot water can exacerbate dandruff or itching. Using slightly cooler water (not cold) during regular hair washing and rinsing has been found to reduce dandruff in some individuals.^{[citation needed]}

See also

• Hair care
• List of cutaneous conditions

References

1. ^ ^{a b} Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 1-4160-2999-0. 
2. ^ ^{a b c d e f g} Ranganathan S, Mukhopadhyay T (2010). "DANDRUFF: THE MOST COMMERCIALLY EXPLOITED SKIN DISEASE". Indian J Dermatol 55 (2): 130–134. doi:10.4103/0019-5154.62734. PMC 2887514. PMID 20606879. http://www.e-ijd.org/article.asp?issn=0019-5154;year=2010;volume=55;issue=2;spage=130;epage=134;aulast=Ranganathan. 
3. ^ "A Practical Guide to Scalp Disorders". Journal of Investigative Dermatology Symposium Proceedings. 2007-12. http://www.nature.com/jidsp/journal/v12/n2/abs/5650048a.html. Retrieved 2009-02-06. 
4. ^ DeAngelis YM, Gemmer CM, Kaczvinsky JR, Kenneally DC, Schwartz JR, Dawson TL (2005). "Three etiologic facets of dandruff and seborrheic dermatitis: Malassezia fungi, sebaceous lipids, and individual sensitivity". J. Investig. Dermatol. Symp. Proc. 10 (3): 295–7. doi:10.1111/j.1087-0024.2005.10119.x. PMID 16382685. 
5. ^ ^{a b} Ro BI, Dawson TL (2005). "The role of sebaceous gland activity and scalp microfloral metabolism in the etiology of seborrheic dermatitis and dandruff". J. Investig. Dermatol. Symp. Proc. 10 (3): 194–7. doi:10.1111/j.1087-0024.2005.10104.x. PMID 16382662. 
6. ^ Ashbee HR, Evans EG (2002). "Immunology of Diseases Associated with Malassezia Species". Clin. Microbiol. Rev. 15 (1): 21–57. doi:10.1128/CMR.15.1.21-57.2002. PMC 118058. PMID 11781265. http://cmr.asm.org/cgi/content/full/15/1/21?view=long&pmid=11781265. 
7. ^ Batra R, Boekhout T, Guého E, Cabañes FJ, Dawson TL, Gupta AK (2005). "Malassezia Baillon, emerging clinical yeasts". FEMS Yeast Res. 5 (12): 1101–13. doi:10.1016/j.femsyr.2005.05.006. PMID 16084129. 
8. ^ ^{a b} Dawson TL (2006). "Malassezia and seborrheic dermatitis: etiology and treatment". Journal of cosmetic science 57 (2): 181–2. PMID 16758556. 
9. ^ Gemmer CM, DeAngelis YM, Theelen B, Boekhout T, Dawson Jr TL (2002). "Fast, Noninvasive Method for Molecular Detection and Differentiation of Malassezia Yeast Species on Human Skin and Application of the Method to Dandruff Microbiology". J. Clin. Microbiol. 40 (9): 3350–7. doi:10.1128/JCM.40.9.3350-3357.2002. PMC 130704. PMID 12202578. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=130704. 
10. ^ Gupta AK, Batra R, Bluhm R, Boekhout T, Dawson TL (2004). "Skin diseases associated with Malassezia species". J. Am. Acad. Dermatol. 51 (5): 785–98. doi:10.1016/j.jaad.2003.12.034. PMID 15523360. 
11. ^ "Genetic code of dandruff cracked". BBC News. 2007-11-06. http://news.bbc.co.uk/2/hi/health/7080434.stm. Retrieved 2010-04-30. 
12. ^ Pierard-Franchimont C, Hermanns JF, Degreef H, Pierard GE (2006). "Revisiting dandruff". Int J Cosmet Sci 28 (5): 311–318. doi:10.1111/j.1467-2494.2006.00326.x. PMID 18489295. 
13. ^ Pierard-Franchimont C, Hermanns JF, Degreef H, Pierard GE. From axioms to new insights into dandruff. Dermatology 2000;200:93-8.
14. ^ Markes R, Pearse A. The effect of a shampoo containing zinc phrithione in the control of dandruff. J Dermatol 1985;112:415-22.
15. ^ Warner RR, Schwartz JR, Boissy Y, Dawson TL Jr. Dandruff has an altered stratum corneum ultrastructure that is improved with zinc phrithione shampoo. J Am Acad Dermatol 2001;45:897-903.
16. ^ Sawleshwakar SN, Salgonkar V, Obrai C. Multi centre, open-label, non-comparative study of a combination of polytar and zinc pyrithione shampoo in the management of dandruff. Indian J Dermatol Venereol Leprol 2004;7:25-8.
17. ^ Shuster S. The etiology of dandruff and the mode of action of therapeutic agents. Br J Dermatol 1984;3:235-42. .
18. ^ Milani M, Antonio Di Molfetta S, Gramazio R, Fiorella C, Frisario C, Fuzio E, Efficacy of betamethasone valerate 0.1% thermophobic foam in seborrheic dermatitis of the scalp. An open label, multicentre prospective trial on 180 patients. Curr Med Res Opin 2003;19:342-5.