Smoker's melanosis

Smoker's melanosis is characterized by flat, irregular hyperpigmentation of the connective tissue underlying the oral mucosa resulting from tobacco smoking. 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 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.

Treatment and Prognosis
The lesion usually disappears if the patient stops smoking. If it does not disappear, however, a biopsy can be used to verify the diagnosis. Smoker's melanosis is benign and does not develop into cancer.