Our skin colour is made from colour forming cells called melanin. Melanin is produced by melanocytes in a process called melanogenesis. Melanin is made within small membrane bound packages called melanosomes.
As they become full of melanin, they are transferred to keratinocytes (skin cells which eventually die and shed away). Under normal conditions, melanosomes cover the upper part of the keratinocyte and protect them from genetic damage. One melanocyte supplies melanin to forty keratinocytes according to signals from the keratinocytes.
Keratinocytes also regulate melanin production and replication of melanocytes. People have different skin colours mainly because their melanocytes produce different amounts and kinds of melanin.
Differences in skin colour are also attributed to differences in size and distribution of melanosomes in the skin. There are two types of melanin (colour forming cells) eumelanin which accounts for brown or black colour and pheomelanin which accounts for yellow or red colour. Eumelanin is found in hair, areola, and skin, and the hair colours grey, black, blonde and brown. In humans, it is more abundant in people with dark skin. Pheomelanin is a pink to red hue is found in particularly large quantities in red hair colours, the lips, nipples, glans of the penis and vagina.
Common pigmentary problems such as melasma and post-inflammatory hyperpigmentation can arise when there is an overproduction of melanin. The causes of melasma can be pregnancy, sun exposure, hormone treatments, certain medication – phototoxic reaction and hypothyroidism. The melanin is taken up in its excess by the keratinocytes producing an epidermal melanosis (superficial hyperpigmentation) and/ or deposited in the dermis producing a deeper dermal melanosis. Types of melasma can be classed as epidermal, dermal or mixed for this reason.
In the dermal type there are melanin-laden macrophages in the superficial and deep dermis. Mixed is bluish light and dark brown patches, partial improvement with treatment. Treatment of melasma is hydroquinone (4%) used twice a day for 12 weeks, tretinoin cream, kojic acid and sunblock.
Post inflammatory hyper pigmentation can develop after there has been an episode of inflammation on the skin due to things like acne, eczema, psoriasis or trauma. Post inflammatory hyper pigmentation treatment is total sunblock, 4% hydroquinone, kojic acid, topical retinoids, peels, glycolic acid, dermamelan.
Dermamelan is a professional treatment for hyperpigmentation. It is carried out by professionals such as dermatologists, dentists and nurses. This is done through the use of two masks over a 3 to 4 month period. The first mask is applied by the doctor, dentist or nurse and left on for a number of hours. Usually around twelve hours. It is vitally important to make sure you leave this mask on for the specified time scale. The second mask is applied weekly thereafter. Again, there will be a tailored regime for your specific skin type and problem which will be determined by the doctor, dentist or nurse. It is important to follow these instructions and report any adverse reactions to your practitioner so that they can make adjustments should you need. Dermamelan acts by blocking the over production of the melanin-producing enzyme (Tyrosinase), therefore, reducing the production of Melasma and other hyperpigmentation problems.
Vitiligo is another pigmentation problem where there is a complete loss of pigment within the skin. All races are equally affected with this condition. Males and females are equally affected too. It is common to develop vitiligo in the first to third decades of life however you can also be born with vitiligo. The aetiology of vitiligo is due to autoimmunity. Vitiligo starts suddenly. The commonest sites are the hands, feet, genitalia and peri ocular and peri oral areas of the face. It tends to have a generalised symmetrical pattern. Or a segmental pattern which follows a dermatome and ceases to progress after one year. Focal form may be an isolated legion which progresses slowly. Vitiligo is symptomless but some patients may complain of itchiness.
Differential diagnosis includes pityriasis versicolor, post inflammatory hyperpigmentation, scleroderma and lichen sclerosis. The treatment of vitiligo involves slow mobility of the melanocytes using topical immunosuppressant creams and ointments as well as phototherapy. Treatment for vitiligo can last more than one year, so patients do need to be committed to have regular treatments. Melanocytes migrate from the margins and also from the hair follicles. Therefore when repigmentation occurs it is around hair follicles and the periphery of the vitiligo. The treatment of vitiligo is topical steroid creams, topical immunosuppressant creams, phototherapy, polypodium leucotomos supplements, elidel cream, vitamin D derivative creams, PUVA treatment and topical prostaglandin as well as camouflage makeup.