Hypermelanosis

Hypermelanosis is a condition arising from an increase in melanin pigmentation in the epidermis or dermis. The skin becomes overly pigmented making it appear darker in patches. The darkened patches may be localized or generalized.

Melanocytes are the cells in the skin that produce the pigment, melanin, that gives the skin its color. Dark skinned people produce more melanin than light skinned people do. An over production of melanin in some areas will result in hypermelanosis.

Hypermelanosis occurs in a variety of conditions

Hypermelanosis is usually patchy in nature and occurs in a variety of conditions including freckles, lentigenes, melasma, moles, neurofibromatosis and Peutz-Jegher’s disease.

Freckles, also known as sun spots are small brown areas of skin that appear mainly on the face and arms. They are hereditary in nature and harmless. They will become darker and more pronounced when exposed to the sun.

Lentigenes are tan - brown clusters of melanocytes approximately 5 – 10 mm in size. They are common in both sexes and are not race specific. They are generally harmless hyperpigmented marks on the skin and although they usually develop in youths in a response to sun exposure will not darken or grow in response to future sun exposure.

Melasma is a hyperpigmentation of the face. It occurs most frequently in women especially those who are pregnant, in which case the condition is called chloasma. Melasma is most common in dark skinned races and tends to run in families. Its exact cause is unknown but it worsens with sun exposure and hormonal changes.

Moles, or nevi, are the most common growth on the human body. They can appear anywhere on the body and can be any shape or size. They generally start as a flat brown spot that grows as the body grows. Over time they may become larger, elevated and grow hairs. Most moles are harmless but some may develop into a melanoma that is a potentially fatal form of cancerous growth.

Neurofibromatosis is a relatively common, progressive, genetic disorder of the nervous system causing tumors to develop on the nerve endings. It is not race specific and occurs equally in both sexes. The signs of neurofibromatosis that present on the skin may include multiple light brown spots measuring 5 – 15 mm in diameter and freckling in the armpits and groin. Two – 5% of people with neurofibromatosis develop internal cancer.

Peutz-Jegher’s disease is an inherited disorder characterised by the presence of gastrointestinal polyps and hyperpigmentation of melanocytes on the lips and mouth and less frequently on the hands and genitalia. The lesions on the lips and mouth appear as small brown to black spots.