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Skin and ethnicity

Interesting facts about black skin

  • Twice as many sebaceous glands as white skins which create an oily film on the surface to protect against the sun
  • Tendency to scarring; particularly keloid
  • More acidic than white skins
  • Often prone to sensitivity
  • Colour varies; blue black to dark black from light brown to dark brown with copper tones from yellowish black to greyish black, reddish etc
  • Generally shiny, velvet soft, pleasant and fresh to touch
  • Often thicker epidermis than white skin
  • Hyperkeratosis is also fairly frequent occurrence
  • Facial redness takes a dark mauve shade darker than the skin itself
  • Superfluous hair rare
  • Smooth surface allows black skin to resist better to heat and humidity
  • More sweat glands – larger and more visible, sweat secretion a lot more volatile

Pigmentation

Number of melanocytes varies in different areas; the main difference between black and caucasians is the distribution. In dark skins melanosomes (melanin pigment granules) are large and distributed singly, in lighter skins they are smaller and packed in complexes. However both skin colours have the same number of melanocyte cells. Melanin also absorbs free-radicals which are a precursor to ageing – hence black skin ages less quickly.

Hyper-pigmentation

This increased distribution of melanin pigment means hyper-pigmentation is greatly increased in black skins. Black skins can easily develop dark patches of pigmentation as a result of the healing process from injury, burn, cuts, scar etc. Erythema or sensitivity will show as a darkened area. Over-abrasion of the skin eg strong soaps, products with high alcohol content, squeezing the skin can result in pigmentation.  Irregular pigmentation can be a problem. Post inflammatory hyperpigmentation (PIH) can develop after the skin has been irritated or sensitised too much by friction eg wax burns, over stimulation with cleansing brushes and can be a contra-indication to some aesthetic treatments.

Hypo-pigmentation

Loss of pigment caused by depletion of melanocyte cells is highly visible in dark skins. More frequent in people suffering from thyroid conditions, addisons disease and pernicious anaemia.

Increased sudoriferous glands

Both eccrine and aprocrine glands are much larger and more numerous in black skin.  The duct is rounder and less twisted. The duct opens at the surface into a larger and more noticeable pore than caucasian. As there are a greater number the skin perspires more easily. This is needed because black skins absorb light and heat more easily and therefore the skin vaso-dilates quickly, in order to reduce heat the skin therefore needs to perspire quickly.

Increased sebaceous glands

Sebaceous glands are larger and more numerous in black skin. In all skins the number of sebaceous glands is less than sudoriferous glands. Despite this increased number the black skin is not necessarily oilier than caucasian skin nor does it manifest acne lesions as often. There is a strong tendency towards retention hyperkeratosis (thickened skin) and so follicles are often congested and comedones present.

In caucasian skins most sebaceous glands are situated in the superficial part of the dermis and are connected to a hair follicle. In black skins one tenth of the sebaceous glands open directly onto the skin surface via a sebaceous follicle. Extraction work is important when treating black skins but gentle care is needed. Good idea to steam and use desincrustation prior to extraction. Black skins are more resistant to the galvanic current so length of treatment and duration needs to be evaluated. Remember during extraction erythema will not be obvious. Homecare advice is important to maintain clarity of the skin.

Thickened stratum corneum

The stratum corneum is thicker in black skins and has the tendency to hyperkeratosisis. Black skin sheds cells more easily and the skin can develop an ashen cast as a result. Shedding black skin cells are still darkly pigmented as they still contain pigment granules whilst caucasian shedding skin cells are colourless and transparent as they do not contain pigment granules. This is probably because melanosomes are four times larger in black skin than in white.

As the stratum corneum is thickened dehydration can easily develop and an increase in scaliness may occur.  Regular and gentle exfoliation is needed to desquamate and refine the excess dead cells – but avoid too much friction.

Other skin conditions

 Dermatosis papulosa nigra

Occurs exclusively in black skins and more so in women. The condition forms brown to black lesions that resemble moles. These lesions are seborrhoeic keratosis looking like flat warts that are not painful. They are benign and do not become malignant and can be surgically removed.

Keloid scarring

Black skin tends to heal itself with raised scar tissue known as keloid scarring. This scarring often extends beyond the borders of the wound and can be a result of injury or infection. Treatment is difficult and can consist of radiation therapy, surgery and topically applied steroids to try and break up the scar tissue adhesions. Dermabrasion should be avoided as the skin heals could develop keloids.

Pseudofolliculitis barbae

Hair follicles are curved in black skin to give naturally curly hair. The hairs are susceptible to growing back into the follicle this can cause an inflammatory reaction which results in tender papules. These papules often become infected and filled with pus. Can be mistaken for acne.  Shaving is a main cause of this condition, waxing can also be a cause.