Introduction
Choroidal melanoma has an incidence of ~6 to 9 per million population per year, with an average age of 60 years, and typically in Caucasians.
- ~45-50% of uveal melanomas metastasise 10-15 years after primary uveal melanoma is diagnosed
- Metastasis is blood borne, commonly affecting liver, lung, bone, skin or brain
Dead Giveaways
Orange Pigment:
Caused by lipofuscin accumulation which is associated with areas of SRF. on FAF appears as regions of hyper-AF. Regions of hypo-AF indicate RPE atrophy
Shows the orange pigments, and the progression of choroidal melanoma. From Amselem L, 2007
B-Scan Ultrasound
Melanomas are quantified based on their height (A) and basal diameter (B) in an ultrasound
Green = B, Yellow = A Small Criteria:
A = [1.0, 3.0] | B = [5.0, 16.0]
Medium Criteria:
A = [2.5, 10.0] | B < 16.0
Large Criteria:
A > 10.0 | B > 16.0
MOLES:
Mushroom Shape
0 -> absent
1 -> unsure/early growth through RPE
2 -> Present
Orange Pigment
0 -> absent
1 -> unsure/trace
2 -> confluent clumps
Large Size
0 -> Thickness < 1.0mm and diameter < 3DD
1 -> Thickness = 1.0-2.0mm and/or diameter = 3-4DD
2 -> Thickness > 2.0mm and/or diameter > 4DD
Enlargement
0 -> none
1 -> unsure
2 -> definite
Subretinal Fluid
0 -> Absent
1 -> Trace
2 -> definite
Important to add the score at the end. If 0, it is a common naevus, and monitor every 1-2 years. 1 indicates a low risk naevus and requires non-urgent referrals. 2 indicates high risk naevus and requires non-urgent referrals. Over 2 indicates probable melanoma and requires urgent referral
Genetic Mutations:
Prognosis worsens from A to D
Monosomy worse than Disomy
Class 2 worse than Class 1
BAP1 mutation worse than EIF1AX, SF3B1/SRSF2
Subset | Metastatic Potential | mRNA GEP | Chromosome 3 | Chromosome 8q | Chromosome 6p | Key mutations | Inflammation |
A | Low | Class 1 | disomy | disomy | Partial or total gain | EIF1AX | No |
B | Intermediate | Class 1 | disomy | partial gain | Gain | SF3B1 | No |
C | High | Class 2 | monosomy | trisomy or more | - | BAP1 | No |
D | High | Class 2 | monosomy | trisomy or more, or isochrome 8q | - | BAP1 | Yes |
diagnostic features
Risk Factors:
Age 50-70years
Fair skin colour
Many skin naevi
Sensitivity to sunburning
Melanocytoma or ocular melanocytosis
Family history
Germline mutations
Symptoms:
Blurred or distorted vision
VF loss
Flashes of light
Changes in iris colour
Can be accompanied by drusen, which at times can be difficult to distinguish from orange pigments
Clinical Recognised Choroidal Melanoma:
Possible melanoma depends on documented growth and symptoms
Clinical retinal detachments and subretinal fluid and orange pigment
Histopathological features: tumour size (basal height), location (choroid, ciliary body and iris)
Tumours histology include:
Involves spindle, epithelioid or mixed
ECM patterns (vasculogenic mimicry --> forms own vascular like channels and endothelial cells to provide oxygen and nutrients)
Immune cells can have tumour associated macrophages and tumour-infiltrating lymphocytes
