Pigmented lesions of the oral mucosa
I. Melanocytic system and abnormalities of cutaneous-mucosal pigmentation:
- The pink coloration of the oral mucosa is mainly due to the hemoglobin contained in the blood vessels of the chorion,
- The presence of melanocytes being much lower than in the skin 8 percent of the cells of the basal layer of the epithelium of the oral mucosa
- The melanoblast is the precursor of melanocytes responsible for the synthesis of melanin, this cell has an organelle the melanosome
- The number of melanosomes provides information on the activity of melanocytes with keratinocytes, which form a true functional entity.
- Abnormalities of cutaneous and mucosal pigmentation may be quantitative or qualitative, or due to the abnormal presence of an exogenous or endogenous pigment.
- Depending on the case, an increase in the number of melanosomes or melanocytes, migrations or pigment discharge is observed at a given level of the epithelium or the chorion.
II. Diagnosis of a pigmented lesion:
- Depending on whether it is a single pigmented lesion, pigmented spots, or diffuse hyperpigmentation, the diagnostic guidelines are different:
- It is necessary to specify whether it is a mucous, papular, infiltrated, nodular or even tumoral lesion.
- Specify seat, size, color, uniform or not, black brown, grayish, bluish, purplish
- The examination should look for extraoral elements, at the level of other mucous membranes, the skin and appendages.
- The interrogation eliminates a transient non-mucous coloration, due to toothpaste, liquorice, tartar use of charcoal….
- The age of the lesions, the notion of associated diseases, and medication intake are specified.
- The fear of malignant melanoma justifies performing a biopsy at the slightest doubt.
III. Clinical study:
1. Malignant melanoma:
- The localizations in the oral cavity are quite characteristic
- Brown or blue-black spot, often polychrome, with more or less regular, slightly prominent borders, painless,
- Elderly subject, sixties;
- Preferred location: Palate, gums,
- The diagnosis is often late,
- The data of the histological examination are identical to those of cutaneous malignant melanoma: presence of tumor cells with melanic pigmentation
- The treatment is wide excision with lymph node dissection if the lesion is significant.
- The prognosis is poor only on the mucosa due to late diagnosis, the anatomical difficulty of performing wide excisions, and the richness of the vascularization of the oral mucosa which favors metastatic dissemination.
Image of a malignant melanoma located at the level of the attached gingiva
2.Lentigo or labial melanotic macule:
- Sits mainly at the level of the lower lip
- Measures from 0.5 to 1 cm in diameter
- Its evolution is benign
- Histological examination shows epithelial hyperplasia with acanthosis and papillomatosis,
- Melanic pigmentation of the basal layers and melanic pigment discharge from the underlying chorion.
Image showing a lower labial lentigo
3. Cellular nevus, blue nevus:
- Rare in the oral mucosa
- They sit willingly at the palace level
- Macular or slightly papular lesion
- Most often of a uniform color and a diameter of less than 1 cm.
- The fear of malignant melanoma justifies their excision.
4.Tattoos:
- Result from the accidental or voluntary introduction of foreign bodies into the oral mucosa
- In case of doubt, histological examination demonstrates the presence of foreign bodies within often sclerotic tissues without reaction.
Image showing a lip tattoo Image showing an intra mucosal amalgam
5. Oral lesions of Kaposi’s disease:
Appear as dark red or purplish pigmented macules.
- The lesions progress towards extension, creating plaques or nodules which are sometimes ulcerated.
- Preferred seat: the palate, tongue and gums.
- Histological examination shows normal epithelium with vascular proliferation.
Img: Manifestations of Kaposi’s sarcoma in the oral mucosa and on the skin
6. Isolated diffuse pigmentations:
6.1 Ethnic, congenital pigmentation:
- More common in people with dark skin tones
- The most common site is adherent gingiva
- The appearance is that of homogeneous slate beaches, with clear boundaries.
- The anamnesis easily allows them to be linked to their origin.
6.2 Post-inflammatory hypermelanosis:
Hyperpigmentation of the oral mucosa can appear during an inflammatory process; these are pigmentary discharges from the same location as previous lesions observed, whether traumatic, infectious, or due to a general condition.
7. Diffuse pigmentation associated with a general endocrine or metabolic disease:
7.1 Adisson’s disease:
Adrenal insufficiency is responsible for diffuse hypermelanosis.
Oral mucosal involvement is very common
It manifests itself as slate-gray spots located mainly on the inside of the cheeks.
7.2 Folate and vitamin deficiency:
Nutritional deficiencies, particularly vitamin B12; C and folic acid can lead to pigmentation of the skin, nails and oral mucosa.
7.3 Jaundice:
During jaundice, the entire oral mucosa is orange-yellow in color.
8. Diffuse pigmentation associated with dermatosis
8.1 Lichen Nigricans
In pigmented lichen planus black plaques, located on the inner surfaces of the cheeks, lips, soft palate
Histological examination shows a typical lichen appearance of the oral mucosa with the presence of a melanin pigment
8.2 Nevus of OTA:
Congenital segmental hyperpigmentation
More common in black and Asian subjects
It affects the face unilaterally in the cutaneous territory of the first and second branches of the V
Involvement of the oral mucosa results in an extensive bluish-gray area of the palate.
Malignant transformation is exceptional.
Histologically, the ectopic presence of melanocytes is noted in the dermis and the chorion.
9. Diffuse pigmentation associated with intoxication :
9. 1 Drug causes:
Many medications can cause pigmentation of the oral mucosa.
This may be due to melanin pigmentation or abnormal accumulation of the drug or one of its derivatives.
Synthetic antimalarials can cause a blue-gray, macular hyperpigmentation of the palate
Regression is slow after stopping treatment
Phenytoin exceptionally causes hyperpigmentation of the oral mucosa after prolonged treatments.
9.2 Tobacco: Smokers’ melanosis:
Gingival hypermelanosis which affects several interdental papillae and can become more diffuse in the gums
It is linked to melanocytic hyperactivity which could be induced by nicotine
9.3 The black hairy tongue:
The blackish-brown pigmentation of the black hairy tongue is due to the development of chromogenic microorganisms at the level of the hypertrophied filiform papillae of the tongue.
- Special form of glossitis
- Due to hypertrophy of the filiform papillae taking on a brown or even black tint through oxidation of the keratin;
- It is most often wrongly classified as a mycoses,
- The search for candida is most often negative, and it resists classic antifungal treatments,
- Mycological culture sometimes finds candida geotrichom without its pathogenic role being confirmed.
Conclusion :
Pigmented lesions of the oral mucosa have a very varied etiology, the diagnosis is essentially based on questioning and a rigorous orofacial examination, in case of doubt, the use of biopsy is essential in order to successfully carry out the therapeutic management.
Good oral hygiene Regular scaling at the dentist Dental implant placement Dental x-rays Teeth whitening A visit to the dentist The dentist uses local anesthesia to minimize pain