Smoker's melanosis
Encyclopedia
Smoker's melanosis is characterized by flat, irregular hyperpigmentation
Hyperpigmentation
In dermatology, hyperpigmentation is the darkening of an area of skin or nails caused by increased melanin.-Causes:Hyperpigmentation may be caused by sun damage, inflammation, or other skin injuries, including those related to acne vulgaris...

 of the connective tissue
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...

 underlying the oral mucosa
Oral mucosa
The oral mucosa is the mucous membrane epithelium of the mouth. It can be divided into three categories.*Masticatory mucosa, para-keratinized stratified squamous epithelium, found on the dorsum of the tongue, hard palate and attached gingiva....

 resulting from tobacco smoking
Tobacco smoking
Tobacco smoking is the practice where tobacco is burned and the resulting smoke is inhaled. The practice may have begun as early as 5000–3000 BCE. Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes...

. Basal cells and macrophages in the underlying connective tissue contain unusual amounts of melanin, which creates the darker pigmentation. Macrophages are unable to degrade all of the melanin, a phenomenon known as melanin incontinence.

Incidence/Prevalence

A study in Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 showed that 21.5% of smokers and 3% of nonsmokers had lesions that could be classified as smoker's melanosis.

Causes

Smoking is the cause in most cases, although similar hyperpigmentations can sometimes be seen in nonsmokers. Similar hyperpigmentations can be due to physiological pigmentation, amalgam tattoo, suntan, drug-related melasma
Melasma
Melasma is a tan or dark skin discoloration. Although it can affect anyone, melasma is particularly common in women, especially pregnant women and those who are taking oral or patch contraceptives or hormone replacement therapy medications...

, Addison's Disease
Addison's disease
Addison’s disease is a rare, chronic endocrine disorder in which the adrenal glands do not produce sufficient steroid hormones...

 (also known as primary adrenal insufficiency), or Post-inflammatory hyperpigmentation.

Treatment and Prognosis

The lesion usually disappears if the patient stops smoking. If it does not disappear, however, a biopsy
Biopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

can be used to verify the diagnosis. Smoker's melanosis is benign and does not develop into cancer.
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