There are many factors leading to dull and dark skin tone: different volume of congenital melanin due to inheritance factor; prolonged exposure to UV rays generating tyrosine and stimulating melanin formation; the slow metabolism and the slow skin regeneration due to stress, unhealthy living style and sleep deprivation.

Light brown freckles are in round shapes, commonly distributed around cheeks and nose. Freckles are common for people who have more congenital melanin. Besides, skin generates tyrosine during exposure to UV rays, which stimulates melanin formation. If the metabolism is not working properly, the melanin will be over-accumulated, making freckles more visible.

Sun spots, also known as solar lentigo or aging spots, are formed due to prolonged UV exposure without proper UV protection. Skin generates tyrosine during exposure to UV rays, which stimulates melanin formation and causing skin aging. UV rays also stimulate the proliferation of epidermal cells, increased accumulation of dead skin cells and melanin. Aging spots gradually form after 30s and they will become protruding as we age.

Melasma is also named as Chloasma or Mask-of-Pregnancy. The pigment usually appears as an irregular brown or dark brown patch around eyes and on cheeks symmetrically. One of the factors of Melasma would be the stimulation of the UV light. Congenital factor such as excessive melanin accelerates spots formation. The epidermal layer will generate excessive melanin, making melasma more visible due to prolonged UV exposure. The occurrence of Melasma is related to hormones change. Melasma is likely to appear on females during their pregnancy or menopause period. Use of Poor-quality cosmetics containing lead and other chemical components will irritate the skin and cause chronic inflammation, leading to concentrated melanin. Pressure, unbalanced diet, lack of sleep and other bad habits will make melanin increases. Besides, some drugs will facilitate the formation of melanin, or affect the normal metabolism of melanin, resulting in melanin accumulation, making spots more visible.

Birthmarks are also known as ‘’café au lait spots’’, which are often present at birth in the dermis. They are usually in light brown color and might vary in size.

Nevus Zygomaticus presents as a brown or bluish-grey patch on the malar region, which is congenital. It is very common in Asian population and more frequently in females. It is a dermal melanocytic proliferation that usually appears during adolescence or adult life. Each spot is around 2mm to 5mm in size and gradually merges into patches. They can become darker during pregnancy.

Nevus of Ota is a skin lesion of blue or grey pigmentation that occurs on the face around the eye areas and temples. The condition is usually congenital, meaning that it occurs before or during birth. It gradually appears during the teenage years. It forms due to hyperpigmentation in the dermis during embryonic development. In some cases, Nevus of Ota may appear in the eye.

Tinea versicolor is most commonly seen as irregular brown patches on chest, back and neck. It is a fungal infection of the skin caused by a type of yeast that naturally lives on your skin. The fungus only starts causing problems when the fungus overgrows due to hot, humid weather and oily skin. Tinea versicolor occurs most frequently in teens and young adults. It is one of the most common skin diseases in summer.

Capillaries form a network under the dermal papilla, plexiform layer or subcutaneous, and is responsible for nutrient transportation and wastes removal for the skin. Telangiectasia, small dilated blood vessels near the surface of the skin, is commonly seen on the face and the legs. The causes of telangiectasia can be divided into congenital and acquired factors. Prolonged UV exposure and long-term use of topical steroid can cause thinning of the skin. Blood vessels become more obvious. External stimulations like showers with hot water, temperature and climate changes will also cause the appearance of telangiectasia. Telangiectasia is the first stage rosacea, a chronic inflammatory skin disease, which begins as redness on the cheeks, nose and chin. Skin would be rosy in initial stage due to UV exposure and alcohol consumption. Red domed papules and pustules will gradually develop. Cyst may also occur in the long run due to fibrosis. Telangiectasia also occurs under hormonal effects such as pregnancy, but will recover after delivery. Fat necrosis due to diabetes, and skin cancers may also result in telangiectasia.

Acne leads to dilation of blood vessels. When acne recovers while the dilated blood vessels are not yet contracted, red marks are resulted. Skin inflammation also damages the skin tissues and causes post-inflammatory pigmentation. The epidermis is unable to regenerate due to skin defect, and thus will be replaced by fibroblast, collagen and new vessels, resulting in acne scars.

Dark circles are caused by hyper pigmentation or poor blood circulation. Slow venous blood flow velocity occurs under circumstances such as staying up late, emotional instability, eye fatigue and aging. Lack of oxygen in red blood cells of eye skin, and excessive accumulation venous carbon dioxide and metabolic wastes will result in chronic hypoxia. Stagnation of blood in the eye area leads to under eye circles.

Hereditary and environmental factors can lead to Eczema. Hereditary factors include genetics and abnormal function of the immune system; while environmental factors include hot and cold temperatures, foods, irritants, and allergens from pets, etc. Eczema can also be caused by damaged epidermis due to chronic skin diseases, scratching or burns. Eczema can be acute or chronic. The symptoms of acute eczema are rashes on the face, erythema, blisters and crusts. When it turns into chronic eczema, skin will become dry, rough and chapped, with crusts and scaling.

Folliculitis is an inflammatory condition affecting hair follicles. Staphylococcus aureus or streptococcus is the most common bacteria leading to Folliculitis. Painful red bumps and tiny pus-filled spots (pustules) develop at the base of a hair, and the surrounding skin may gradually be red and swollen.

Seborrheic dermatitis is an inflammation with excessive sebum secretion. The affected area will look red, with scales flaking off. It is usually found on the scalp, eyebrows, around the nose or mouth, or behind the ears. The excessive growth of the fungus called Pityrosporum Ovale brings bacterial infection. Many factors seem to work together to cause seborrheic dermatitis. These factors may include the yeast that normally lives on our skin, our genes, living in a cold and dry climate, menstruation, staying up late, stress, and a person’s overall health. The symptoms usually become more severe with excessive alcohol consumption, spicy or greasy foods.

Rosacea is a common skin disease. The exact cause of rosacea is unknown. The main symptoms of rosacea include red or pink facial skin, small dilated blood vessels, and small red bumps sometimes containing pus or cysts. Many people who have rosacea may just assume they have very sensitive skin that blushes or flushes easily. Nose will become swollen and enlarged in severe cases.

A keloid is a heaped-up claw-like scar that rises quite abruptly over normal skin. It usually has a pink or red color and tends to enlarge progressively. It is a result of an overgrowth of fibroblasts at the site of a healed skin injury. Keloids develop most often on the chest, shoulders, earlobes and arms. It may continue to extend beyond the wound site by scratching or external stimulation.

Sebaceous hyperplasia is a benign bump on the skin that forms over time as a result of damage, leading to an ongoing problem with over-productive oil glands. It occasionally occurs on areas with excessive sebum secretion and sweating. It is the root cause in the formation of acne. Vitamin A deficiency may be one of the causes of sebaceous hyperplasia. Most patients, usually young adults, have large pores, with symptoms of itching and tingling.

There are two major types of acne lesions: non-inflammatory and inflammatory. Non-inflammatory acne lesions include blackheads (open comedones) and whiteheads (closed comedones). Inflammatory acnes include pimples, pustules and cysts, which are the clogged of hair follicles due to bacterial infections. A healthy skin rejuvenates every 28 days. If the metabolism is not working properly, dead skin cells will accumulate. The pores will be clogged, hindering sebum excretion, leading to hypoxia. When the pores are closed, hypoxia condition will trigger whiteheads. When the pores are open, the exposure to air allows the plugs in the hair follicle to oxidize, resulting in a dark spots called blackheads. Propionibacterium acne is a normal inhabitant of the skin. It uses sebum as a nutrient for growth, and induces the inflammatory process in the follicles, resulting in the formation of acnes. Exposure to stimulators like polluted air, dust, bad cosmetics, etc, would also induce follicle inflammation and growth of acnes. The secretion of sebaceous gland would be significantly increased in adolescence stage, or before menstruation, due to hormonal changes. Internal dysfunction such as gastrointestinal disorder and constipation, or addiction to greasy, spicy food and desserts, stresses and lack of sleep also accelerate acne formation.

Pores become enlarged due to clogging by dirt and sebum. Aging, lack of skin elasticity and dehydration can also cause pores to dilate. Excessive squeezing or picking acnes will irritate the skin, resulting in depressed scars and enlarged pores. Prolonged use of bad cosmetics that are high in chemical ingredients will also cause large pores.

Scars form after physical trauma such as stab wound, burns and scalds, skin tissue protrusion or depression due to surgery. In skin wound healing, activated fibroblasts are stimulated to produce new collagen. An accumulation of excess collagen may give rise to a raised scar. If the dermis is damaged and cannot regenerate itself enough to replace all of the damaged tissue, a depressed scar will be resulted.

Acne Scars are formed by post-inflammatory hyperpigmentation. It is a type of transitional scars and will fade away over time. Skin inflammation leads to dilation of blood vessels. When acne recovers while the dilated blood vessels are not yet contracted, temporary flat red marks are resulted. If the dermis is damaged and collagen cannot regenerate itself enough to replace all of the damaged tissue, a depressed scar will be resulted.

Mole is a benign located along the junction of the epidermis and the underlying dermis. Its size and shape are affected by congenital factor. Generally, moles are developed after birth and they will be gradually raised with age, due to a proliferation of naevus cells.

Warts is caused by the infection of Human Papilloma Virus (HPV). The virus is spread through small wounds during human contacts. Warts are commonly found on face, back of the hands, fingers and palms. They are flat, flesh-color or light brown rough texture tiny spots. The number of warts can be increased, and may occur alone or appear in groups.

Eye bags are mild swelling or puffiness under the eyes. Orbital septum is a membranous sheet between the muscles and fat in lower eyelid. It prevents the orbital fat from herniating forwards when we are young. However, the septum may weaken with age, or due to chronic fatigue and over-usage. Fat slips out and eye bags will be formed.

Saggy skin and wrinkles develop as we age. Subcutaneous fat will droop due to insufficient support and gravity. Subcutaneous fat layer shifts from the upper half to the lower half of the face. The overall appearance will change, such as having sunken eye sockets, prominent cheekbones, or a double chin.

Facial muscles develop with expressions. With the gradual loss of protein, the facial muscles lose support and results in sagging face.

Bone density decreases gradually with age. The structure of bones becomes atrophic, leading to sunken eye sockets and gaunt face.

Nose is at the centre of the face. Facial symmetry and aesthetics are highly affected by shapes and sizes of the nose. Besides, low nasal bridge, oversized or exposed nares, square jaw, thick subcutaneous fat and chewing muscles, short chin will also have an obvious effect on the facial aesthetics.

Decreased metabolism and long-term UV damage lead to loss of collagen and elastin in the dermis. Skin will droop and develop wrinkles and lines. Forehead lines are one of facial expression lines due to loss of elasticity, and they can deepen and become permanent over time. Besides, smoking, lack of sleep, hormonal imbalance and unhealthy living habit also accelerate the appearance of wrinkles.

Eye wrinkles, one of the facial expression lines, are formed due to repeated facial muscle movements. As we age, moisture retention capacity of the skin around the eyes will gradually decrease. Dehydration and a lack of sebaceous glands around the outer corners of the eyes could accelerate the appearance of eye wrinkles. Eye wrinkles such as crow’s feet are developed by repeated contraction of eye muscles, and loss of collagen, elastin and fat. Besides, saggy forehead skin will increase the burden of the upper eyelids. As such, droopy eyelids and gaunt face occur.

Nasolabial folds are the two skin folds that run from each side of the nose to the corners of the mouth. As we age, skin becomes saggy due to collagen loss, making nasolabial folds more visible.

The skin gradually loses support due to aging and collagen loss. Neck skin is thin and brittle with insufficient sebaceous gland and sweat glands. Thus neck folds develop easily due to limited sebum excretion and low moisture retention capacity. Metabolism decreases as we age. When the collagen production cannot keep pace with its loss, skin becomes loose and wrinkles develop.

Female breast sagging is a natural consequence of aging. As women age, breasts naturally yield to gravity and tend to sag, especially for larger-breasted women. Another reason is significant weight gain or loss. Besides, during pregnancy, the ovaries and the placenta produce estrogen and progesterone. These hormones stimulate the milk-secreting glands in the breasts to develop. The skin is stretched during engorgement while lactating. When milk production stops, the voluminous mammary glands diminish in volume resulting in sagging.

Poor circulation results in the decrease in lymph drainage, causes the fluids which should carry away waste to be trapped. The decreased circulation also weakens capillaries and veins, causing the surrounding fat continue to be deposited. Cellulite is the herniation of subcutaneous fat within fibrous connective tissue that manifests topographically, often on the buttocks, upper limbs, and forearms. When the structural support of the skin starts to collapse and the fat cells push through it, skin dimpling and nodularity are resulted.

Stretch marks are often the result of the rapid stretching of the skin associated with rapid growth or rapid weight changes. This causes the elastic fibers just under the surface of the skin to break, resulting in stretch marks, appearing as red or white lines with different widths and lengths.

Many people are slim but still cannot get rid of stubborn fat when the metabolism is not working properly. The lymphatic blockage enlarges fat cells, leading to obesity and bloating. As we age, decreased metabolism results in the decrease in lymph drainage, causes the fluids which should carry away waste to be trapped. Sagging skin develops and fat gradually accumulates to result in tummy and flanks.

The perineum is essential particularly for females. It supports the uterus, rectum and urinary bladder. Since the beginning of pregnancy, estrogen will be released to increase blood flow to the folds of the vagina so that this elastic connective tissue is better able to expand and stretch during childbirth. Relaxin will also be released to help the body to relax and loosen the ligaments and joints in the pelvis so it is able to expand and create space for the baby. The perineum may be left stretched after the delivery, leading to problems like bladder leaking and uterine prolapse. Enlarged labia may also prone to inflammation due to repeated frictions and bacterial infections.

Hair, a kind of skin appendages, is one of the defining characteristics of mammals. It used to help regulate body temperature and protect the skin. With human evolution, sweat glands are now responsible for body temperature regulation instead. The growth cycle of hair can be divided into three phases, including growth (anagen), degradation (catagen), and resting (telogen) phases. Hairs contain a large amount of melanin in the anagen phase. Hairy appearance creates an untidy impression.