Synonyms: melasma, mask of pregnancy, chloasma medicamentosum
Chloasma comes from the Greek chloazein, to be green. It is considered to be something of a misnomer and many dermatologists prefer the term melasma (melas is Greek for black).
This is largely unknown but many differences have been noted between chloasma and normal skin. There is an increase in the level of melanin, large numbers of melanocytes and melanosomes and increased synthesis of tyrosinase. One study also found an increased level of solar elastosis (increase in elastin tissue resulting from sun exposure) and propounded that chloasma was a result of a cumulative sun exposure, in a micro-environment of cutaneous photo-ageing in which inflammatory cells, particularly mast cells, play a key role. Another found an increase in oestrogen receptor expression, suggesting an hormonal link.
The exact incidence of chloasma is unknown, but it is a common condition.There is a female to male predilection in a ratio of 9:1.
- Dark skin - it is common in people of Asian and Hispanic origin.
- Hormonal - chloasma occurs commonly in pregnancy. One study in Iran found a prevalence, among 400 pregnant patients, of 15.8%. It is rare before puberty and is most common in women during their reproductive years. It is linked to use of oral contraceptives. One study of patients with chloasma found that the frequency of thyroid disorders was four times greater compared with a control group.
- Sun exposure - this is a well-established risk factor. Chloasma occurs in sun-exposed areas of the skin.
- Genetics - 30% of patients report a positive family history and identical twins with chloasma have been reported.
- AIDS - one study reported a group of AIDS patients who developed chloasma-like hyperpigmentation of the face.
- Other pigmented lesions - one study found a higher incidence of chloasma in women who also had lentigines or melanocytic naevi.
- Patients usually complain of gradual-onset areas of dark skin.
- The colour may vary from tan to brown, but may be black or have a bluish tinge.
- The distribution is usually symmetrical and three patterns are commonly seen - centrofacial, malar or mandibular.
- Addison's disease.
- Drug-induced photosensitivity.
- Discoid lupus erythematosus.
- Mastocytosis (mast cell proliferation and accumulation within various organs, most commonly the skin).
- Poikiloderma of Civatte (erythema associated with a mottled pigmentation seen on the sides of the neck, more commonly in women).
Wood's light helps to locate the pigmentation in the dermis or epidermis. In many cases it is found in both locations.
- Chloasma is a difficult condition to manage, as sunlight is a considerable aggravating factor and it is difficult to prevent exposure even with high-factor protection creams.
- Mild cases may simply require reassurance. Chloasma associated with pregnancy should resolve spontaneously within a few months. A variety of therapies are available but, if treatment in primary care is unsuccessful after six months, specialist referral should be considered.
- Lightening agents seem to be the best treatment. Hydroquinone 4% has been the one most commonly used but its availability is restricted in some parts of the world due to concerns about its long-term effects (mainly exogenous ochronosis, an irregular blue-black staining affecting sun-exposed skin and nails). It is, however, still currently available in the UK. Other lightening agents that have been tried include t-retinoic acid, ascorbic acid and azelaic acid, either alone or in combination.
- T-retinoic acid used as monotherapy can be effective but improvement is slow. It is thought to act by inhibiting the function of melanosomes.
- Triple therapy cream containing hydroquinone, tretinoin and fluocinolone acetonide has been found in one study to be more cost-effective than hydroquinone alone.
- Other agents that have been tried include 4-n-butylresorcinol, phenolic thioether, 4-isopropylcatechol and kojic acid. One study reports that pidobenzone 4% lipogel used twice a day for sixteen weeks is safe and effective. Azelaic acid can be as effective as 4% hydroquinone and is more effective than 2%. The mechanism of action is not well understood.
- Sometimes a peeling agent such as glycolic acid is added.
- Laser treatment, intense pulsed light therapy and medium-depth chemical peels are also sometimes employed to hasten resolution:
- Some authorities believe these destructive 'quick fix' therapies to be unpredictable and associated with an increased incidence of adverse events (eg epidermal necrosis, postinflammatory hyperpigmentation and hypertrophic scarring).
- Recent developments in technology have resulted in lasers which are safer and more effective; they have been used successfully in patients resistant to other forms of treatment.
- Light microscopy studies show a general reduction in melanocyte content after a certain type of laser treatment (fractional photothermolysis).
- Intravenous vitamin C has been used to reduce hyperpigmentation after laser treatment.
Most cases resolve eventually, but can take a long time to do so. Continued exposure to sunlight tends to hamper treatment and lead to recurrence. Resolution will also take longer in patients with extensive dermal melanin compared to those in whom pigmentation is mainly in the epidermal layer.
Further reading & references
- Melasma, DermNet NZ
- Victor FC, Gelber J, Rao B; Melasma: a review. J Cutan Med Surg. 2004 Mar-Apr;8(2):97-102. Epub 2004 May 4.
- Hernandez-Barrera R, Torres-Alvarez B, Castanedo-Cazares JP, et al; Solar elastosis and presence of mast cells as key features in the pathogenesis of melasma. Clin Exp Dermatol. 2008 May;33(3):305-8.
- Lieberman R, Moy L; Estrogen receptor expression in melasma: results from facial skin of affected patients. J Drugs Dermatol. 2008 May;7(5):463-5.
- Montemarano A et al, Melasma; Medscape, Mar 2011
- Moin A, Jabery Z, Fallah N; Prevalence and awareness of melasma during pregnancy. Int J Dermatol. 2006 Mar;45(3):285-8.
- Foldes EG; Pharmaceutical effect of contraceptive pills on the skin. Int J Clin Pharmacol Ther Toxicol. 1988 Jul;26(7):356-9.
- Lutfi RJ, Fridmanis M, Misiunas AL, et al; Association of melasma with thyroid autoimmunity and other thyroidal abnormalities and their relationship to the origin of the melasma. J Clin Endocrinol Metab. 1985 Jul;61(1):28-31.
- Adalatkhah H, Sadeghi-bazargani H, Amini-sani N, et al; Melasma and its association with different types of nevi in women: a case-control study. BMC Dermatol. 2008 Aug 5;8:3.
- Gupta AK, Gover MD, Nouri K, et al; The treatment of melasma: a review of clinical trials. J Am Acad Dermatol. 2006 Dec;55(6):1048-65. Epub 2006 Sep 28.
- Bleaching Creams, DermNetz NZ, 2009
- Cestari T, Adjadj L, Hux M, et al; Cost-effectiveness of a fixed combination of hydroquinone/tretinoin/fluocinolone cream compared with hydroquinone alone in the treatment of melasma. J Drugs Dermatol. 2007 Feb;6(2):153-60.
- Zanieri F, Assad GB, Campolmi P, et al; Melasma: successful treatment with pidobenzone 4% (K5lipogel). Dermatol Ther. 2008 Jul;21 Suppl 1:S18-9.
- Guevara IL, Pandya AG; Safety and efficacy of 4% hydroquinone combined with 10% glycolic acid, antioxidants, and sunscreen in the treatment of melasma. Int J Dermatol. 2003 Dec;42(12):966-72.
- Polnikorn N; Treatment of refractory dermal melasma with the MedLite C6 Q-switched Nd:YAG laser: two case reports. J Cosmet Laser Ther. 2008 Sep;10(3):167-73.
- Goldberg DJ, Berlin AL, Phelps R; Histologic and ultrastructural analysis of melasma after fractional resurfacing. Lasers Surg Med. 2008 Feb;40(2):134-8.
- Lee GS; Intravenous vitamin C in the treatment of post-laser hyperpigmentation for melasma: a short report. J Cosmet Laser Ther. 2008 Dec;10(4):234-6.
|Original Author: Dr Laurence Knott||Current Version: Dr Hayley Willacy||Peer Reviewer: Dr John Cox|
|Last Checked: 19/10/2011||Document ID: 1946 Version: 23||© EMIS|
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