Oral pigmented lesions Flashcards
List the causes of mucosal colour changes
- Increase or loss of keratin
- Endogenous pigments (blood or melanin)
- Foreign material (amalgam, metals, dyes and diet)
- Bacterial pigments
What are melanocytes?
Melanin producing cells located in the basal layer of the skin’s epidermis
What do melanocytes look like histologically?
Dark cells with long processes (Dendritic processes) extending to the surface
When does melanin increase
With exposure to the sun (UV rays)
What happens when there is a generalised increase of melanin in a normal distribution?
More melanin at the basal layer and less degrading of melanin by cells travelling to the surface - therefore more melanin at the surface = darker colour
What is melanin drop out/
Melanin is passed (dropped) into the connective tissue, where it is harder to degrade thus forming a dark patch
What is a melanotic macule
Common, benign pigmented lesions due to increased melanin in focal distribution (freckle)
What is lentigo
Small pigmented spot on the skin with clearly defined edges due to benign hyperplasia of melanocytes at the basal cell layer
Difference between lentigo and melonotic macules?
Lentigo is associated with more melanocytes at the basal cell layer which causes more melanin drop out
What syndrome is lentigo associated with?
Peutz-jegher syndrome
What is peutz-jegher’s syndrome
Autosomal dominant disorder characterised by the development of benign hamartomatous polyps in the GIT and hyperpigmented macules on the lips and oral mucosa
Describe the oral lesions in Peutz-Jeghers syndrome
Blue lesions on the lips Brown lesions (lentigo) on the skin and around lips (looks like lots freckles)
What is oral melanoacanthiosis (melanocanthoma)
Rare, benign pigmented lesion characterised by a macular brown-black lesion and histologically by acanthiosis of the superficial epithelium and proliferation of dendritic melanocytes
What is a benign acquired melanocytic naevus
Common, benign lesion made of cluster of melanocytes (also called moles)
Presentation of melanocytic neavus
Round, dome shaped and raised
Can range from brown to black (or no colour) and often have large and coarse hair follicles
Pathology of melanocytic neavus
Increased number of melanocytes in the epithelium which pass into the connective tissue where they produce the melanin
History of melanocytic neavus
First develop in early childhood and continue to grow until the age of 30 where they stop growing
What is a melanoma in situ?
Presence of malignant melanocytes confined to the epidermis (no spread)
Warning signs of melanoma in situ?
Non-healing, ulcerated or bleeding mole
Satellite pigmentation around the mole
Association with lymph nodes
Common site for melanoma in situ?
Palate
Moles here should always be monitored or biopsied
How does melanoma in situ spread?
Melanocytes increase and cluster together, where they break through the basement membrane and spread into the connective tissue and into other tissues where they release melanin
What path does melanoma in situ tend to spread?
Along the trigeminal nerve branches
What is giant hairy melanocytic neavus?
Congenital skin condition characterised by a large, dark and benign patch with a large number of hair follicles, resulting from melanocytes lost in migration
What stage is the melanoma at during radial growth phase?
- Superficial spread of the melanoma (it starts growing sideways)
- Still shallow and easy to treat
How do melanomas spread?
- Radial growth phase
- Vertical growth phase with metastases
Describe oral melanomas
Irregular borders with satellite pigmentation
Brown, blue or black depending on the depth of tissue and amount of melanin
May be ulcerated
What is Hutchinson’s freckle/lentigo maligna
Pigmented and premalignant lesion (consists of malignant cells without invasive growth) usually on a sun exposed area in elderly patients
What is an example of melanoma in situ?
Hutchinsons freckle
What is acanthiosis nigricans?
Skin disorder characterised by dark and thickened (hyperkeratotic) patches found in the folds of the skin (armpits, neck, groin and forearms)
What is acanthiosis nigricans associated with?
Internal malignancy
Diabetes
Presentation of acanthiosis nigricans
Located in folds - neck, armpits, forearms
Uni or bilateral
Usually dry, dark and thickened, may feel like velvet
Oral lesions in acanthiosis nigricans
Can affect the mucous membranes
However, often non-pigmented
What are amalgam tattoos
Benign, pigmented lesion due to implantation of amalgam particles into the mucosa where they disperse over time
Presentation of amalgam tattoos
Brown, black or blue lesion associated near an amalgam restoration
RG will show RO amalgam in the tissue
Histology of amalgam tattoos
Dark pigments (amalgam) with foreign body giant cells associated with the amalgam
What are lead lines?
Blue pigmentation of the mucosa (the gingival margin) due to heavy metal toxicity
What is black hairy tongue
Harmless oral condition caused by overgrowth and pigmentation of the filiform papilla found at the midline of the posterior tongue
How does black hairy tongue arise?
Pigment arises from bacteria producing melanin like pigments
Aetiology of black hairy tongue
Stress, radiotherapy or spontaneous
Tends to be worse in smokers
Oral pigmentation due to lichen planus
Causes postinflammatory pigmentation - multiple black or brown areas associated adjacent to LP lesions
How does lichen planus cause discolouration of the mucosa?
Inflammatory cells under the epithelium become destroyed and the melanocytes drop into the connective tissue
How can UV destroy DNA cells?
UV is absorbed by DNA which can distort the helix by thymide dimer, they can be repaired but not if they are damaged or broken
List effects of UV on the skin
- Sunburn
- Photoaging
- Keratosis solaris
- Photosensitivity
- Carinogenesis
Describe UV-A rays
- Low energy rays causing superficial, short lived tans
- Can cause photoaging and carcinoma
Descrive UVB rays
Higher energy rays causing deeper, long lasting tans
- Can cause deeper damage and sunburn
Which type of UV ray is more dangerous?
UVC but it is blocked by the ozone layer
Describe aged skin
Loss of elasticity, atrophy and reduced metabolism
Describe photoaged skin
Patchy hyperpigmentation Thickened dermis Distored microvasculature Prone to purpura Leathery and nodular Loss of elasticity
What is photoaged skin?
Skin damage due to prolonged sun exposure from UVA and UVB rays
