Pigmented lesions of the mouth and face Flashcards
What is the function of melanin?
Melanin in epidermis functions as a protective sunshade for the DNA of basal cells
How can an increase in melanin pigmentation arise?
Increase of melanin synthesis
Increase of the number of melanocytes
Where is melanin synthesised and what happens to it as it progresses up to the surface
Melanin is synthesised by oral melanocytes (found in basal layer) and passed to adjacent keratinocytes by phagocytosis
As keratinocytes progress up to the surface, they degrade the melanin and the cells fall off unpigmented
What does the colour of melanin vary with
varies with its depth in the mucosa
Why is taking a biopsy of an oral pigmented lesion mandatory
to distinguish between pigmented lesion and melanoma
What are the main causes of colour change in the mucsoa? (5)
Melanin pigmentation Extrinsic agents Superficial, enlarged or numerous BVs Haemorrhage or blood pigments Inflammation
What are the causes of diffuse mucosal inflammation (4)
- Addison’s disease (late stage)
- Drugs (NSAIDs, phenothiazines, CHX, hydroxychloroquine/antimalarials)
- Remote carcinoma (usually around palate)
- Heavy smoking (commonest cause)
What is the cause of physiological pigmentation and what type of pigmentation does it cause?
Which part of oral cavity is most affected?
What is another name for physiological pigmentation?
- Caused by increase in activity of melanocytes (but normal number)
- Causes localised melanin pigmentation - although pigmentation may be widespread, it is in well-defined symmetrical zones
- Gingivae is particularly affected and inner aspect of the lips often spared
- Commoner in those with dark skin and is often called ‘racial pigmentation’
What is the cause of Melanotic macules and what type of pigmentation does it cause?
Which part of oral cavity is most affected?
Describe clinically and what is the management?
What disease can it be associated with?
- Caused by increased melanocyte activity
- Causes localised menlanin pigmentation
- Found on gingiva, buccal mucosa and palate
- Well defined flat brown-black pigmented patches that are few mm in diameter
- They are benign but appearance is indistinguishable from early melanoma so usually excised for confirmation of diagnosis
- HIV (6% of pts)
What is the management of oral melanocytic naevi?
What are the three types?
What are the clinical presentations of each?
What are the histological causes of each?
- All asymptomatic but should be excised to exclude early malignant melanoma
1. Acquired melanocytic naevi (aka moles) - appear in childhood and grow until adolescence then regress until 30
- While they regress naevus cells produce less melanin and migrate deeper and become inactive
- Usually flat black patches 5-6mm on palate/gingiva
- Caused by the proliferation of melanocytes forming a mass between epithelium and CT
- Blue naevus
- Deeply sited cluster of pigmented naevus cells (blue colour)
- Most often on the palate of children or young adults
- Focus of spindle-shaped pigmented melanocytes lies deep - Congenital naevi
- Cannot be distinguished from acquired naevi when they arise in the mouth
What is the clinical presentation of a melanocanthoma?
What is the cause histologically?
What is the management?
- Asymptomatic flat/domed brown-black patches with ill-defined periphery
- Found at any intraoral site
- Enlarge over several weeks, remain stable and then slowly regress
- Increase in melanocytes, increase melanin production and the melanocytes migrate up from basal layers to all levels in the epithelium
- Biopsy necessary to exclude melanoma (excision if lesion is small)
How does post inflammatory pigmentation occur?
What is the most common inflammatory condition to become pigmented?
- Inflammation interferes with both melanin synthesis and its transfer to keratinocytes
- Malanosomes can escape from the epithelium into the underlying CT where it is taken up by macrophages (melanin ‘drop out’)
- Accumulation gives rise to post-inflammatory pigmentation
- Lichen planus is the most common inflammatory condition to become pigmented
What syndrome causes oral pigmentation?
What are the clinical presentations of it?
What is the cause and the histological cause?
What is the management?
- Peutz-Jeghers syndrome
- Characterised by mucocutaneous pigmented macules and intestinal polyposis
- Cutaneous patches usually fade after puberty but oral macules persist (resemble malonotic macules)
- Caused by mutation of STK11 gene
- Increased number of melanocytes in basal layer and more melanin in basal cells and epithelium
- Lesions cause slight acanthosis and are lentigos and not melanotic macules
- No tx required but refer pt for genetic diagnosis
What is the clinical presentation of an amalgam tattoo?
What is the histological cause?
- Fragments get embedded in the oral mucosa forming 5mm+ across grey tattoos
- Initially sharply defined but amalgam becomes dispersed and lesions slowly enlarge and develop irregular outlines
- Large dense tattoos may be radiopaque
- Histologically brown-black granules deposited along collagen bundles and around small blood vessels
Clinical presentation of Lead line and heavy metal (mercury/bismuth/lead) poisoning?
What is the histological cause?
- These metals pass in solution from serum into the crevice where they are reduced to sulphides by bacterial products and are visible through the thin gingival margin as a dark black-brown line (Burton’s line)
