Oral Pigmented Lesions

Pigmented lesions are commonly found in the mouth. Such lesions represent a variety of clinical entities, ranging from physiologic changes (e.g., racial pigmentation) to manifestations of systemic illnesses (e.g., Addison¿s disease) and malignant neoplasms (e.g., melanoma and Kaposi¿s sarcoma). Therefore, an understanding of the causes of mucosal pigmentation and appropriate evaluation of the patient are essential. Oral pigmentation may be exogenous or endogenous in origin. Exogenous pigmentation is commonly due to foreign-body implantation in the oral mucosa. Endogenous pigments include melanin, hemoglobin, hemosiderin and carotene. Melanin is produced by melanocytes in the basal layer of the epithelium and is transferred to adjacent keratinocytes via membrane-bound organelles called melanosomes. Melanin is also synthesized by nevus cells, which are derived from the neural crest and are found in the skin and mucosa. Pigmented lesions caused by increased melanin deposition may be brown, blue, grey or black, depending on the amount and location of melanin in the tissues.