Oral Lichen Planus and Lichenoid Reactions Flashcards
Oral lichen planus features?
Common, 1.5% of population Onset 30-50yrs old Cell mediated auto-immune condition Stress may exacerbate it Chronic, difficult to treat 1-3% reported risk of malignant change Different clinical presentations - Reticular - Plaque like - Erosive - Desquamative gingivitis - Bullous
Skin involvement in lichen planus?
<10% of patients presenting with oral lesions have skin
lesions
~50% of patients presenting with skin lesions have oral
lesions
Purple, itchy papules + Wickham’s striae
Lesions particularly occur on flexor surface of wrists and
on the shins
Skin/cutaneous lichen planus?
0.9-1.2% of populations Worldwide Middle to late life Both genders Rare in childhood
Where else can lichen planus occur?
Oesophageal
Genital
Anal
Oesophageal
Histology of lichen planus?
Suggestive of a cell mediated auto-immune disease process
= IV hypersensitivity = damage to the basal cells and disruption of the basement membrane
Keratin layer on top
Atrophic epithelium
CT with many T lymphocytes in the lamina propria
Pathology of lichen planus?
T cells accumulated and disrupt the basement membrane
Start a cell mediated autoimmune damage to the basal cells
T cells invade the epithelium
Damage to basal cells stimulates an attempt to repair it
If the rate of repair exceeds the rate of damage then epithelial thickening and marked keratinisation may occur
= White lacelike pattern
due to hyperkeratinisation
If rate of damage exceeds the rate or repair then epithelial thinning may occur - erosive/atrophic lesions = large red erosive areas with a white border , or even ulceration
Why are basal keratinocytes targeted for cell mediated autoimmune damage?
Keratinocytes start to express altered self antigen
OR Cytotoxic T cells fail to recognise the keratinocytes as self
Lichenoid lesions
Lesions that look like oral lichen planus clinically and hitologically
Where there is a known antigenic cause
Causes of lichenoid reactions?
Graft vs host disease
Contact sensitivity to dental materials
Reactions to systemic drugs
SLE/OLE
What causes graft vs host disease?
Usually the result of a bone marrow transplant
Transplant usually used to treat haematological malignancies e.g leukaemia
Pt’s bone marrow is ablated with chemo/radiotherapy and reconstituated wth bone marrow from a healthy donor
Pt’s T cells are now someone elses = if slight mismatch in HLA markers the new T cells may regard the pt’s keratinocytes as foreign so they will accumulate
= Damage to basal keratinocytes
How can amalgam cause a reaction?
Amalgam can leach into epithelium = damage to basal keratinocytes
Contact sensitivity reactions - where can they occur?
Oral cavity - not thought capable of displaying contact hypersensitivity reactions until 1980s
Mucosal lesions associated with amalgam fillings though to be caused by galvanism
Reactions occur most frequently with amalgam but also other dental materials
Contact sensitivity reactions?
Lesions closely associated with filling material
Pt is often patch test positive to filling material
Removing or replacing the restoration results in the lesion resolving within 3-6 months
How do systemic drugs cause a reaction?
Absorbed into blood stream and t cells attack
What systemic drugs can cause lichenoid reactions?
Anti-hypertensives
- Thiazides
- Propranolol
Anticoagulants
- Dipyridamole
- Phenindione
Antimalarials
- Quinine
Anti-inflammatories
- Chloroquine
- Gold
- NSAIDs
- Penicillamine
Diabetes tx
- Chlorpropamide
- Metformin
Anti-microbials:
- Metronidazole
- Tetracycline
Carbimazole
Psychiatric drugs
- Lithium
