Melasma: Types, Causes, Risk Factors, Symptoms, Diagnosis, Differential Diagnosis Treatment

Melasma is a skin condition that causes the appearance of brown, blue-grey, or freckle-like areas on the skin. A lot of people call it the "mask of pregnancy." Melasma is caused by an overproduction of the cells that determine the colour of your skin. It is widespread and safe, and some treatments could be helpful. Melasma typically goes away after a few months.

Read this blog further to get a quick overview of this important topic for DERMATOLOGY to ace your NEET PG exam preparation.

Types of Melasma 

Melasma comes in three different varieties based on the intensity of the pigment. To ascertain the depth of the pigment, we utilise a Wood lamp that generates black light. They are as follows:

• Epidermal: Epidermal melasma is characterised by a dark brown colour, a clearly defined border, and the ability to be seen under a black light. It can occasionally react favourably to therapy.
• Dermal: Dermal melasma has a hazy border, a light brown or bluish colour, and does not change under a black light. It also does not respond well to treatment.
• Mixed Melasma: The most prevalent of the three, mixed melasma has both bluish and brown patches, has a mixed pattern under black light, and exhibits some therapeutic response.

Causes of Melasma

Melasma has a complicated aetiology, although it has been suggested that in people with certain genetic predispositions, it is a photoaging illness. The pigmentation is ultimately caused by melanocyte's excessive synthesis of melanin, which is then either taken up by keratinocytes in the case of epidermal melanosis or deposited in the dermis in the case of melanophages.

Melasma formation has been linked to a number of factors, including:

• Family history – 60% of respondents indicate affected relatives
• UV and visible light from the sun encourages the formation of melanin.
• One-quarter of the affected women have hormone-related issues, including pregnancy, the use of oestrogen/progesterone-containing oral contraceptives, intrauterine devices, implants, and hormone replacement treatment.
• Melasma and thyroid problems can coexist
• New targeted therapy for cancer and perfumed soaps, shampoos, and cosmetics may provoke a phototoxic reaction that results in the development of melasma.

Risk Factors For Melasma

The majority of persons who develop melasma have a history of regular or irregular sun exposure, while heat is also thought to be a contributing factor. Pregnant women are more likely to experience it, particularly those of Latino and Asian ancestry. Melasma is more common in those with olive or darker skin tones, such as those who are Hispanic, Asian, or Middle Eastern. Males rarely develop melasma.

It is believed that the following are mostly responsible for melasma:

• Exposure to sunlight outside
• Hormonal supplements, such as birth control tablets,
• Alterations to internal hormone levels during pregnancy

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Symptoms of Melasma

Discolouration or hyperpigmentation, usually on the face, is a defining feature of melasma.

Melasma exhibits three different sorts of typical facial patterns, including the following:

• (Centrofacial) Centre of the face
• the malar cheekbones
• (Mandibular) jawbone

The centrofacial pattern, which is the most common type of melasma, contains the following:

• Forehead
• Cheeks
• upper lip
• Nose
• Chin
• Upper cheeks also feature the malar pattern. 

Less frequently, melasma can affect the upper sides of the neck. Melasma might sporadically appear on other body areas, such as the forearms. According to one study, people receiving progesterone have melasma on their forearms. An investigation of Native Americans revealed this particular trend.

How is Melasma Diagnosed? 

Melasma is typically diagnosed with a clinical examination that includes a dermatoscope and Wood lamp.

Sometimes a skin biopsy may be performed. The histology varies depending on the type of melasma, however, the following characteristics are frequently present:

• Basal and suprabasal keratinocytes deposit melanin.
• Strongly pigmented, highly dendritic (branched), melanocytes
• The dermal melanophages' melanin
• fragmentation of elastic fibres and solar elastosis
• An expansion of blood vessels.
• To track therapy response, serial photography and severity indices like the Melasma Area and Severity Index (MASI) or modified MASI might be utilised.

What are the potential melasma differential diagnoses?

Clinically, the following conditions can seem similar to melasma:

• Inflammatory aftereffects of hyperpigmentation
• Acquired dermal macular hyperpigmentation, including solar lentigo and various lentigines and freckles
• Hyperpigmentation caused by medication
• Naevus of Ota and Hori

Treatment of Melasma

Sun protections are to be used such as sunscreen, goggles, hats, etc. 

Topical treatments

• Hydroquinone, glycolic acid, azelaic acid, and kojic acid are used.
• Kligman's formula is used in this, it is a combination of 3 agents- hydroquinone (act as depigmented agent), topical retinoid (act as an exfoliant), and mild topical steroid (reduces the inflammation that is present and is caused by retinoids).
• Chemical peels are topical agents in a concentrated manner and are done by physicians. The purpose of it is glycolic, azelaic acid, kojic acid, lactic acid, and topical retinoids are all present in higher concentrations, it is applied on the patient's face, kept for 5 minutes and then washed off. These are concentrated chemicals which penetrate deeper, causing exfoliation of the skin. 

Systemic treatments

• Tranexamic acid and glutathione are used. 
• Lasers can also be used for these patients. 

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