Melasma

Sinónimos: cloasma, máscara del embarazo, cloasma medicamentosum

Previously known as chloasma (which originally comes from the Greek chloazein, to be green), melasma is now considered to be the better term (melas es griego para negro).

¿Qué es el melasma?

Melasma is a common acquired condition of hyperpigmentation, typically occurring on the face. Multiple aetiologies, including light exposure, hormonal influences, and family history, have been implicated in pathogenesis.¹ It is thought that UV radiation, in combination with hormonal factors, acts on people with a genetic predisposition to result in abnormal melanocyte activation leading to excess melanogenesis.²

¿Quiénes padecen melasma? (Epidemiología)¹³

• La incidencia exacta del melasma es desconocida, pero es una condición común. La prevalencia varía significativamente según la región geográfica.

• Women are much more likely to be affected by men, with men making up about 10% of the diagnoses.²

• It is rare prior to puberty and tends to develop between the ages of 20 and 50.

• It is more common in Fitzpatrick skin types III to V.⁴

Factores de riesgo para el melasma⁵

Estas incluyen:

• Fitzpatrick skin types 3, 4 and 5 - that is, the type of skin which is naturally brown or tans very well.

• Factores hormonales:

  • Melasma occurs commonly in pregnancy. One study in Iran found a prevalence, among 400 pregnant women, of 15.8%.⁶ In Pakistan, it has been shown to be as high as 46% and in other studies up to 70%.

  • El melasma asociado con el embarazo generalmente se resuelve espontáneamente dentro de un año después del parto.

  • It is rare before puberty and is most common in women during their reproductive years.

  • It has long been linked to oral contraceptive use⁷but more recent data also shows a link with contraceptive implants.⁸ Both progesterone only and combined oral contraceptives appear to be implicated.⁹All studies suggest that the hormonal intra-uterine systems are less likely to cause melasma, although they can do so.

  • También hay una asociación con la autoinmunidad tiroidea.

• Sun exposure. This is a well-established risk factor. Melasma occurs in sun-exposed areas of the skin and may improve in winter and worsen after sun exposure.

• Genética. Hasta el 40% de los pacientes informan antecedentes familiares positivos y se han reportado gemelos idénticos con cloasma.

• Medication. Commonly used medications which can result in melasma include metronidazole, clarithromycin, finasteride, anastrazole and paroxetine. ⁷¹⁰

Síntomas del melasma¹

• Patients usually complain of a gradual onset of areas of darker skin.

• Gradual onset is typical with episodic worsening during periods of increased UV or visible-light exposure.

• Typically melasma consists of symmetrical, hyperpigmented macules and patches with irregular borders and uniform coloration, predominantly affecting the face.

• Classic facial distribution patterns include centrofacial, malar, and mandibular involvement

• El color puede variar de tostado a marrón, pero puede ser negro o tener un tono azulado.

Images of melasma are available on the DermNet and Primary Care Dermatology Society websites.³¹¹

Diagnóstico diferencial³

• Enfermedad de Addison.

• Haemochromatosis.

• Fotosensibilidad inducida por medicamentos. Las reacciones a medicamentos pueden causar hiperpigmentación a través de varios procesos.

• Discromía madurativa. (Decoloración difusa relacionada con la edad causada por la exposición acumulativa a los rayos ultravioleta.)

• Lupus eritematoso discoide.

• Mastocitosis (proliferación y acumulación de mastocitos en varios órganos, más comúnmente en la piel).

• Poiquilodermia de Civatte (eritema asociado con una pigmentación moteada que se observa en los lados del cuello, más comúnmente en mujeres).

• Lichen planus pigmentosus.

• Pecas.

• Léntigo solar

• Nevus de Ota (manchas de hiperpigmentación de color azul/gris a marrón pizarra, generalmente unilaterales y que suelen presentarse en la infancia o la pubertad).

• Nevus de Hori (máculas bilaterales simétricas de color azul-gris o gris-marrón en las mejillas, que se presentan en adultos).

Investigaciones

Diagnosis is essentially clinical. Dermoscopy may be useful.

Tratamiento y manejo del melasma³¹¹

General

• Sunlight is a considerable aggravating factor - year-round sun protection should be advised, including high factor sun creams. Sun creams containing iron oxide have been shown to be beneficial.¹

• Los casos leves pueden simplemente requerir tranquilidad.

• El camuflaje con cosméticos puede ser útil.

• Melasma associated with pregnancy may resolve spontaneously within a few months.

• Consider changing contraceptive type, although pregnancy is also a significant risk in susceptible women.

• Review the medication in case of a drug-related cause.

Tratamientos tópicos para el melasma

• Most treatments are unavailable on the NHS for treating melasma. No medications are licensed in the UK for melasma.

• Hydroquinone 2-4% is a skin-lightening agent which inhibits conversion of dopa to melanin. It is applied to the affected areas at night for 2-4 months. It is not licensed in the UK but is available to be prescribed by NHS dermatologists on some local formularies (but by no means all).

• Triple therapy cream containing hydroquinone, tretinoin and fluocinolone acetonide has been found in one study to be more cost-effective than hydroquinone alone and benefits 60-80% of those treated.¹² It may cause erythema and scaling. This is also available in some areas for NHS dermatologists to prescribe

• Cysteamine is a known potent depigmenting agent which has shown significant efficacy (as 5% cream) in the treatment of patients with epidermal melasma.¹³

• Ácido azelaico. Se aplica dos veces al día y puede usarse a largo plazo. Puede causar escozor.

• Ascorbic acid (vitamin C).

• Tranexamic acid can be used either orally or topically, off-label and privately.¹³¹⁴

• Tyrosinase inhibitors.

• A variety of newer treatments are thought to have the potential to treat melasma but have not yet been studied adequately. These include thiamidol, kojic acid and arbutin.¹⁵

Peelings químicos

• Chemical peels containing glycolic acid or trichloroacetic acid are used by cosmetic practitioners. They may cause a skin reaction.

Tratamiento con láser¹⁶

Se han utilizado varios tipos de terapia láser, incluyendo:

• Láseres fraccionados

• Lasers Nd:YAG con Q-switch

• Luz pulsada intensa

Pronóstico¹

Melasma typically follows a chronic, relapsing course. Significant improvement is often achieved with consistent therapy, but complete and durable clearance is less predictable without long-term maintenance

Melasma associated with pregnancy usually resolves spontaneously within a year.

El melasma puede afectar negativamente la calidad de vida debido al efecto en la apariencia, particularmente porque tiende a estar en el rostro, con consecuentes secuelas psicosociales. Sin embargo, no es una condición premaligna y es principalmente un problema cosmético.