Pigmentation and Discoloration of Oral and Facial Tissues
Pigmentation is a discoloration of the oral mucosa or gingiva due to the wide variety of lesions and conditions. Oral pigmentation has been associated with a variety of endogenous and exogenous etiologic factors. Also it can be explained as Oral mucosal discolouration, which ranges from brown to black may be due to superficial (extrinsic) or deep (intrinsic in or beneath mucosa) causes.
Types of Oro-maxillofacial Pigmentation
Extrinsic discoloration is usually caused by extrinsic pigments. It is rarely of consequence and is usually caused by colored foods, drinks or drugs. Extrinsic discoloration usually affects both mucosae and teeth are discolored. Causes include the following:
• Foods and beverages, such as beetroot, red wine, coffee and tea.
• Confectionery, such as liquorice.
• Drugs, such as chlorhexidine, iron salts, griseofulvin, crack cocaine, minocycline, bismuth subsalicylate, lansoprazole and HRT.
• Tobacco: this may cause extrinsic discolouration, but can also cause intrinsic pigmentary incontinence, with pigment cells increasing and appearing in the lamina propria. This is especially likely in persons who smoke with the lighted end of the cigarette within the mouth (reverse smoking), as practiced mainly in some Asian communities. Tobacco is a risk factor for cancer.
• Betel: this may cause a brownish-red discolouration, mainly on the teeth and in the buccal mucosa, with an irregular epithelial surface that has a tendency to desquamate. It is seen mainly in women from South and Southeast Asia. Betel chewer’s mucosa epithelium is often hyperplastic, and brownish amorphous material from the betel quid may be seen on the epithelial surface and intra- and intercellularly, with ballooning of epithelial cells. Betel chewer’s mucosa is not known to be precancerous, but betel use predisposes to submucous fibrosis and to cancer.
Causes for intrinsic hyperpigmentation are Increased melanin or number of melanocytes, or other materials. Intrinsic discolouration may have more significance than the extrinsic type. Normal intrinsic pigmentation is due to melanin, produced by melanocytes dendritic cells prominent in the basal epithelium.
Localized areas of pigmentation are usually caused by benign conditions:
• Embedded amalgam (amalgam tattoo)
• Embedded graphite (graphite tattoo)
• Other foreign bodies
• Local irritation/inflammation
• Melanotic macule
However, neoplasms, such as Kaposi sarcoma or malignant melanoma, are occasionally responsible. The anterior pituitary gland releases melanocyte stimulating hormone (MSH), which increases melanin production. Melanin pigmentation thus increases under hormonal stimulation, either by MSH, or in pregnancy, or rarely due to the action of adrenocorticotrophic hormone (ACTH), the molecule of which is similar to MSH, or under the influence of other factors (e.g. smoking). Thus in all patients systemic causes should be excluded, such as:
• Drugs; including smoking and the contraceptive pill
• Hypoadrenalism; there is increased ACTH production
• Peutz–Jeghers syndrome
• HIV infection
• Von Recklinghausen’s disease
• Albright syndrome
• Rarely, palatal pigmentation from bronchogenic carcinoma.
|Peutz Jeghers Syndrome|
List Causes of hyperpigmentation
• Amalgam, graphite, carbon, dyes, inks or other tattoos
• Ephelis (freckle)
• Epithelioid angiomatosis
• Kaposi’s sarcoma
• Malignant melanoma
• Melanotic macule
• Pigmented neuroectodermal tumour
• Verruciform xanthoma
Multiple or generalized
• Carney syndrome
• Complex of myxomas, spotty pigmentation and endocrine overactivity
• Laugier–Hunziker syndrome
• Lentiginosis profusa
• Leopard syndrome
• Peutz–Jeghers syndrome
• contraceptive pill
• metals (bismuth, mercury, silver, gold, arsenic, copper, chromium, cobalt, manganese)
• Addison’s disease
• Albright’s syndrome
• Nelson’s syndrome
• Gaucher’s disease
• generalized neurofibromatosis
• HIV disease
• incontinentia pigmenti
• Whipple’s disease
Melanin, a nonhemoglobin derived brown pigment, is the most common of the endogenous pigments and is produced by melanocytes present in the basal layer of the epithelium. Melancocytes have a round nucleus with a double nucleus membrane and clear cytoplasm lacking desmosomes or attachment plates. Melanin accumulates in the cytoplasm, and the melanosome is transformed into a structureless particle no longer capable of melanogenesis. The number of melanocytes in the mucosa corresponds numerically to that of skin; however,in the mucosa their activity is reduced. Various stimuli can result in an increased production of melanin at the level of mucosa including trauma, hormones, radiation, and medications.Thyrosinase activity is present in premelanosome and melanosomes but absent in melanin granules.
Granules of melanoid pigment are scattered in the stratum lucidum and stratum corneum of the skin. Initially it was assumed melanoid was a degradation product of melanin, but more recently it has been shown that such a relationship is highly improbable. Melanoid imparts a clear yellow shade to the skin.3
Oxyhemoglobin and Reduced Hemoglobin
Oxyhemoglobin and reduced hemoglobin are pigments resulting from hemosiderin deposits.
The skin color is affected by the capillary and venom plexuses shining through the skin.
Carotene is distributed in the lipids of the stratum corneum and stratum lucidum and gives a deep yellow color to the skin. It is found in higher concentrations in more women than in men. Pigmented lesions of the oral cavity are of multiple origin. Different classifications are used at this time. Some researchers divide the lesions into two main groups as either endogenous or exogenous lesions. Brocheriou et al.
subdivides pigmented lesions as follows:
• Non tumoral pigmentations
• Non melanin pigmented tumors or tumor like lesions
• Benign melanin pigmented tumors
• Malignant melanomas
In several articles on oral pigmentation, Dummett and others implicate many systemic and local factors as causes of changes in oral pigmentation.
Oral pigmentation occurs in all races of man.There were no significant differences in oral pigmentation between males and females. The intensity and distribution of racial pigmentation of the oral mucosa is variable, not only between races, but also between different individuals of the same race and within different areas of the same mouth. Physiologic pigmentation is probably genetically determined, but as Dummett suggested , the degree of pigmentation is partially related to mechanical, chemical, and physical stimulation. In darker skinned people oral pigmentation increases, but there is no difference in the number of melanocytes between fair-skinned and dark-skinned individuals. The variation is related to differences in the activity of melanocytes.There is some controversy about the relationship between age and oral pigmentation. Steigmann and Amir et al. stated all kinds of oral pigmentation appear in young children. Prinz, on the other hand, claimed physiologic pigmentation did not appear in children and was clinically visible only after puberty.
The gingivae are the most frequently pigmented intraoral tissues. Microscopically, melanoblasts are normally present in the basal layers of the lamina propria.The most common location was the attached gingiva (27.5%) followed in decreasing order by the papillary gingiva, the marginal gingiva, and the alveolar mucosa.The total number of melanophores in the attached gingival was approximately 16 times greater than in the free gingival. The prevalence of gingival pigmentation was higher on the labial part of the gingiva than on the buccal and palatal/lingual parts of the arches.The shade of pigment was
classified as very dark brown to black, brown, light brown-yellow.3 Melanin pigmentation of the
oral tissues usually does not present a medical problem, but patients complain of black gums.
Classification and Differential Diagnosis
Oral pigmentation has been associated with a variety of lesions and conditions. Differential diagnosis of oral mucous membrane pigmentations are made according to the following situations:
A. Localized Pigmentations: Amalgam tatoo, graphite or other tattoos, nevus, melanotic macules, melanoacanthoma, malignant melanoma, Kaposi’s sarcoma, epithelioid oligomatosis, verruciform xanthoma
B. Multiple or Generalized Pigmentations
1. Genetics: Idiopathic melanin pigmentation (racial or physiologic pigmentation), Peutz-Jegher’s syndrome, Laugier-Hunziker syndrome, complex of myxozomas, spotty pigmentation, endocrine overactivity, Carney syndrome, Leopard syndrome, and lentiginosis profuse
2. Drugs: Smoking, betel, anti-malarials, antimicrobials, minocycline, amiodarone, clorpromazine, ACTH, zidovudine, ketoconazole, methyldopa, busulphan, menthol, contraceptive pills, and heavy metals exposure (gold, bismuth, mercury, silver, lead, copper)
3. Endocrine: Addison’s disease, Albright’s syndrome, Acanthosis nigricans, pregnancy, hyperthyroidism
4. Postinflammatory: Periodontal disease, postsurgical gingival repigmentation
5. Others: Haemochromatosis, generalized neurofibromatosis, incontinenti pigmenti, Whipple’s disease, Wilson’s disease, Gaucher’s disease, HIV disease, thalassemia, pigmented gingival cyst, and nutritional deficiencies
Systemic and Local Causes of Pigmentation
Many systemic and local factors are caused by changes in oral pigmentation. Some of the important factors are discussed below.
The pigmentation of the oral mucous membrane by tooth restoration material (amalgam) is a
common finding in dental practice. Amalgam pigmentation is generally called amalgam tattoo.The lesion represents embedded amalgam particles and usually manifests itself as an isolated bluish or black macule in various areas of the mucosa. The color is usually described as black, blue, grey, or a combination of these. Almost half were located on the gingiva and alveolar mucosa, the mandibular region being affected more than the maxillary region. Almost half of the lesions were asymtomatic and were discovered during routine dental examination. The amalgam granules and fragments were found mainly in the lamina propria but were sometimes seen in the submucosa.
Pigmented nevi of the oral cavity are uncommon. The pigmented nevi are classified as intramucosal, junctional, compound, or blue according to their histological features. Nevi are seen particularly on the vermillion border of the lips and the gingivae. They are usually grey, brown, or bluish macules and are typically asymptomatic. Melanocytes are pigment producing cells characterized by the ability to syntesize via the enzyme dihydroxyphenylalanine (DOPA). A group of melanocytes (generally four or more) are in contact with the basal layer of the epithelium.
Oral Melanotic Macules
Oral melanotic macules are relatively rare oral mucosal lesions, analogous to skin freckles, due to the focal increase of melanin production.These melanotic macules have been variously termed ephelis, melonosis, lentigo, solitary labial lentigo, labial melanotic macule, and oral melanotic macule.The vermillion border of the lower lip is most commonly involved.The buccal mucosa, palate, and gingiva are less commonly affected. The color is usually described as grey, brown, blue, black, or a combination of these.Histologically, ephelis shows increased melanin pigmentation in the basal cell layer without an increase in the number of melanocytes; otherwise, the epidermis is normal.
Melanoma is a cancerous condition of the melanocyte. Special corpusles in this cell, known as melanosomes, contain the necessary enzyme (tyrosine) to transform amino acids into melanin. Melanocytes are found among the basal cells of the epidermis. Histopathogically, the mucosal epithelium is abnormal with large atypical melanocytes and excessive melanin. Malignant melanoma of the oral mucosa affects both sexes equally usually after 40 years of age. The great majority of the lesions (about 70-80%) occur on the palate, upper gingival, and alveolar mucosa.Initially there usually is a solitary small asymtomatic brown or black macule.
Physiologic pigmentation of the oral mucosa is clinically manifested as multifocal or diffuse melanin pigmentation with variable prevalence in different ethnic groups.2 Melanin is normally found in the skin of all people. In dark skinned persons the gingiva may contain melanin pigment to a greater extent than the adjacent alveolar mucosa. The melanin pigment is synthesized in specialized cells, the melanocytes, located in the basal layer of the epithelium. The melanin is produced as granules. The melanosomes are stored within the cytoplasm of the melanocytes, as well as in the cytoplasm of adjacent keratinocytes. Melanocytes are embryologically derived from neural crest cells that eventually migrate into the epithelium. If pigmented gingiva is surgically resected, it will often heal with little or no pigmentation; therefore, surgical procedures should be designed so as to preserve the pigmented tissues.
Peutz-Jeghers syndrome (intestinal polyposis) is a genetic disorder characterized by mucocutaneous pigmentation and hamartomas of the intestine.It manifests itself as frecklelike macules about the hands, perioral skin, and intraorally to include the gingiva, buccal, and labial mucosa. Pigmented spots are 1 to l0 mm in diameter. Pigmented spots are particularly found on the lower lip and buccal mucosa but rarely on the upper lip, tongue, palate, and gingiva.
Smoker’s melanosis is a benign focal pigmentation of the oral mucosa. It tends to increase significantly with tobacco consumption. Tobacco smokers have significantly more oral surfaces pigmented than non-tobacco users.Clinically, the lesion usually presents as multiple brown pigmented macules less than 1 cm in diameter, localized mainly at the attached labial anterior gingival and the interdental papillae of the mandible. Smoker’s melonosis is more common in females usually after the third decade of life.
Antimalaria Drug Use
Several antimalarial drugs are known to be capable of inducing intraoral melanin pigmentation. These drugs include: quinacrine, chloroquine, and hydroxychloroquine Longterm use may cause pigmentation of the oral mucosa. The pigmentation of the oral mucosa is described as slate-grey in color, bearing some resemblance to pigmentation caused by silver arsplenamine.
Minocycline is a synthetic tetracycline that is commonly used in the treatment of acne vulgaris.Although tetracycline causes pigmentation of bones and teeth, minocycline alone is also responsible for soft tissue pigmentation.It is usually seen as brown melanin deposits on the hard palate, gingiva, mucous membranes, and the tongue.
Heavy metals absorbed systemically from therapeutic use or occupational environments may discolor the gingiva and other areas of the oral mucosa. Bismuth, arsenic, and mercury produce a black line in the gingiva which follows the contour of the margin. Lead results in a bluish red or deep blue linear pigmentation of the gingival margin (Burtonian line). Exposure to silver causes a violet marginal line, often accompanied by a diffuse bluish-grey discoloration throughout the oral mucosa.
Addison’s disease or primary adrenocortical hypofunction is due to adrenocortical damage
and hypofunction.Bronzing of the skin and increased pigmentation of the lips, gingivae, buccal mucosa, and tongue may be seen. Oral pigmentation may be the first sign of the disease.A biopsy of the oral lesions shows acanthosis with silver-positive granules in the cells of the stratum germinativum. Melanin is seen in the basal layer.
Periodontal diseases often produce discolorations of the oral mucosa. The pigmentation is worsened by gingivitis, which increases vascular permeability and allows the heavy metals access to the soft tissues.51 Melanin re-pigmentation is related to after surgical inury.
Hemachromatosis (bronze diabetes) is a chronic disease characterized by the deposition of excess iron (ferritin and hemosiderin) in the body tissues, resulting in fibrosis and functional insufficiency of the involved organs. Hyperpig mentation may appear both in skin and mucous membranes (oral and conjunctiva). Gingival or mucosal pigmentation is reported to occur in 15 to 25% of patients with hemachromatosis. The oral mucosa shows diffuse homogeneous pigmentation of gray-brown or deep brown in about 20% of the cases. The buccal mucosa and the attached gingiva are the most frequently involved sites.
In patients infected with human immunodeficiency virus (HIV), progessive hyperpigmentation of the skin, oral mucosa, fingernails, and toenails have been reported being related to primary adrenocortical deficiency and to zidovudine (azidothymidine) therapy in some cases.Clinically, oral pigmentation appears as irregular macules with brown or dark brown color. The tongue, buccal mucosa, and palate are the most commonly affected sites.