The most common causes of hyperpigmentation are:
Sun Exposure: The body produces more melanin to protect the skin from prolonged exposure to the sun. This can cause dark spots or patches on the skin called age spots or sunspots.
Skin Inflammation: Post-Inflammatory Hyperpigmentation occurs after there is damage or irritation to the skin. The skin involved turns tan or brown .Areas of the skin can darken after people have had inflammation of the skin due to inflammatory eruption or injury .
This can include acne, eczema, insect bite reaction, dermatitis, post viral infections, seborrhoeic dermatitis, sunburn, or an injury to the skin. People with darker skin are more likely to develop post-inflammatory hyperpigmentation.The time taken to decrease pigmentation can take days to years and can be psychologically distressing.
Maturation Dyschromia: it means darkening of facial skin tone .
Dark circles or Periorbital pigmentation: the cause of dark circles can be multifactorial including genetics, allergy, hormonal, nutritional deficiencies.
Riehl Melanosis: it is also known as pigmented contact dermatitis occurs due to application of contactants especially cosmetics
Melasma: Darker patches of skin with irregular borders occur in centrofacial or malar or mandibular areas of face. can form when people experience hormonal changes. This type of hyperpigmentation is commonly seen during pregnancy, sun exposure, hormonal imbalance or certain oral medication.
It’s also called chloasma, or the “mask of pregnancy”. The condition is much more common in women than men, though men can get it too.
Reactions to drug use: Certain medications, such as antimalarial drugs can cause hyperpigmentation. In these cases, patches of skin may turn grey. excessive use of cosmetics and certain over the counter creams can also sometimes cause hyperpigmentation.
Freckles: Freckles are small brown spots on your skin, often in areas that get sun exposure. In most cases, freckles are harmless. They form as a result of the overproduction of melanin, which is responsible for skin and hair colour (pigmentation).
Solar lentigines: commonly seen in people of age over 40. Age spots are small, flat dark areas on the skin. They vary in size and usually appear on areas exposed to the sun, such as the face, hands, shoulders and arms. Solar lentigo is a harmless patch of darkened skin. Post-Acne Pigmentation: Those dark marks or spots left behind after a pimple heals, can be even more aggravating and distressing than pimples themselves. PIH is discolouration of the skin that follows an inflammatory wound. It is the skin’s natural response to inflammation. Exogenous ochronosis – it occurs as blue black pigmentation on face ,sides and back of neck ,back . It occurs due to excessive use of cosmetic creams containing hydroquinone. Acanthosis nigricans– Typically presents with darkening and thickening of skin on face,axilla,posterior neck Dermatosis papulosa nigra and seborrheic keratoses: it presence as 1 to 5 mm pigmented papules present on cheeks, neck, chest and back Nevi: Different types of nevi or birthmarks or moles can be present as dark patches on any part of the body .they can be present from pin head size to several millimeters in diameter .onset is usually at any age ashy dermatosis: It is usually present as slate grey to blue brown oval dark patches typically involving trunk ,neck and sometimes in face. Lichen planus pigmentosus: It is seen as irregularly shaped grey brown to brown patches in sun exposed areas . usually asymptomatic but some complain of itching or burning