malignant melanoma

Question 1

definition of malignant melanoma

Answer 1

malignancy arising from neoplastic transformation of melanocytes - the pigment forming cells of the skin

leading cause of death from skin disease

Question 2

aetiology of malignant melanoma

Answer 2

DNA damage in melanocytes caused by UV radiation = neoplastic transformation

short periods of intense UV exposure - particularly in the early years

50% arise in pre-existing naevi, 50% in previously normal skin

Question 3

different histopathological types of malignant melanoma

Answer 3

superficial spreading (70%)

nodular (15%)

lentigo maligna (10%)

acral lentiginous (5%)

Question 4

superficial spreading melanoma

Answer 4

arise in pre-existing naevus

expoand in radial fashion before vertical growth phase

grow slow and met later

better prognosis than nodular

Question 5

nodular melanoma

Answer 5

arise de novo

agressive

no radial growth phase

invade deeply

met early

may be amelanotic in 5%

Question 6

lentigo maligna melanoma

Answer 6

more common in elderly with sun damahe

large flat lesions

follow an indolent growth cause

usually on the face

evolve from pre-existing lentigo maligna

Question 7

acral lentiginous melanoma

Answer 7

arise on palms, soles and subungal areas

most common type in non-white populations

Question 8

epidemiology of malignant melanoma

Answer 8

steadily increasing incidence

6000/yr dx in UK

lifetime risk 1 in 80 in US

white races have 20 times increased risk to non-white

commonly affects younger people

Question 9

sx of malignant melanoma

Answer 9

change in size, shape or colour of pigmented lesion

redness

bleeding

crusting

ulceration

Question 10

signs of malignant melanoma

Answer 10

ABCD criteria for examining moles

• A - asymmetry
• B - border irregularity/bleeding
• C - colour variation
• D - diameter >6mm
• E - elevation

Question 11

Ix for malignant melanoma

Answer 11

excisional biopsy - for histological dx and determination of Clark’s levels or Breslow thickness

lymphoscintigraphy - radioactive compound is injected around the lesion and dynamic images are taken over course of 30mins to trace the lymph drainage and the sentinal nodes

sentinal LN biopsy (if primary and <1mm depth) - sentinal LN are dissected and histologically examined for met involvement

staging - US, CT, MRI, CXR

blood - LFT (liver common site of met)

Question 12

Glasgow 7 point checklist for malignant melanoma

Answer 12

refer if 3 or more points, or with 1 point if suspicious

• change in size (2pts)
• change in shape (2pts)
• change in colour (2pts)
• inflammation (1pt)
• sensory change (1pt)
• dm >7mm (unless growth in a vertical plane) (1pt)
• Crusting/bleeding (1pt)

Question 13

breslow thickness

Answer 13

depth of malignant melanoma in mm

Question 14

prognostic factors for malignant melanoma

Answer 14

breslow thickness

tumour stahe

ulceration

Question 15

summarise congenital malignant naevi

Answer 15

usually >1cm

present at birth or in the early noenatal period

if >20cm = increased risk of malignant change

Question 16

summarise acquired melanocytic naevi

Answer 16

present in childhood or in young adults and have characteristic evolution

start as flat evenly pigmented naevi - nests of melanocytes collect along the basal layer of the epidermis = junctional naevi

as melanocytes migrate from the epidermis to the dermis - moles evlove into raised evenly pigmented dome-shaped naevi = compound naevi

then the epidermal component is lost and moles change into pale brown papules = intradermal naevia

disappear in old age

Question 17

summarise halo naevi

Answer 17

common in adoplescence

a white halo develops around a benign melanocytic naevi

not sinister and results from loss of melanocytes by lymphocyte action

in adults - mayu indicate melanoma elsewhere - check skin, eyes and mucosal surfaces

Question 18

definition of melanocytic naevi

Answer 18

benign neoplasms or hamartomas made of melanocytes

most commonly as small, brown, flat macules, raised mammillated dome-shaped papules, bluish-grey macules and papules, and even amelanotic skin-coloured papules.

Unless congenital, they first appear in childhood

more common in people with light skin and eyes.

Question 19

epidemiology of melanocytic naevi

Answer 19

very common, >98% of white people have at least 1 by early childhood

usually between 15-40 acquired naevi - regress with increasing age

less common in Asian and black people

halo naevi <20yrs, on back

Congenital nevi are stated to occur in <2% of the population

Nevus spilus may be a congenital nevus with a prevalence of no more than 2% of the population

spitz naevia - children and younger adults, usually acquired

Atypical, dysplastic, or Clark’s nevi are sporadic or familial, are estimated to have an incidence of between 2% and 10%, and can be acquired throughout life

Question 20

aetiology of melanocytic naevi

Answer 20

genetic predisposition for formation of the naevi is likely

acquired are more common in fair skin and light eyes

sun exposure - because associated with tendency to burn, and history of severe burns

increase in prev with decreasing latitude

Question 21

pathology of melanocytic naevi

Answer 21

Melanocytes are neural crest-derived cells that migrate to the epidermis during embryogenesis

In addition to the epidermis, melanocytes are normally found in hair follicles, the uveal tract of the eye, the leptomeninges, and the cochlea.

Question 22

sx and signs of melanocytic naevi

Answer 22

presence since birth

asymettrical, indistinct, irregularly borderd, variably coloured papules with dm >5mm

Atypical, dysplastic, or Clark’s nevi may have a ‘fried egg’ appearance, with a central papular component and a flat peripheral component, and may have indistinct borders.[26]

Larger than 5 mm, and may have variable coloration from pink to tan to brown.

history of change in shape and colour - become more raised or dome shaped, get lighter or darker over time, spitz have a history of growing rapidly

asymptomatic

multiple lesions

flat, brown macule - Junctional acquired nevi are often small, flat, uniformly brown macules.

dome shaped papule - Compound and dermal nevi are often dome-shaped and tend to have uniform pink, tan, or brown coloration.

light brown background with speckled darker brown spots within - nevus spilus

blue-grey dome shaped papule - Common blue nevi are solitary blue-grey to black papules or flat macules that are usually <1 cm and often found on the dorsal extremities, head and neck, and sacrum

central pink to brown papule with surrounding depigmented white ring - halo nevus

pinkish-brown papule - spit naevi often found on the face and lwoer extremities as pink or red-brown papules with a smooth or verrucous surface

Question 23

RF for melanocytic naevi

Answer 23

genetic predisposition - fair skin and white eyesm in those with a tendency to freckle and burn, with a history of burns

fair skin

older children and young adults - Children acquire more nevi as they grow older, with the peak for adults being in their third decade. Excludes congenital nevi

Question 24

Ix for melanocytic naevi

Answer 24

dermatoscopy:

• patterns depend on type - generally show symmetrical structures and colours
• have 1 or 2 colours - reflect the location of the pigment in the skin
• black and brown = pigment in the epidermis
• grey and blue = pigment in the superficial and deep dermis respectively
• reticular pattern (grid of brown lines overlies a light brown background and globular pattern, with numerous brown, round-oval structures)
• cobblestone - variation of globular pattern, papillomatous or mammillated dermal nevus
• homogenous pigment (diffuse grey-blue to grey-black pigmentation w/o other patterns, blue naevi)
• starburst - pigmented streask in a radial arrangement of the edge, spitz naevi
• dysplastic or clark’s naevi - asymmetrical pink, brown and tan colouration - pigment network may be typical or atypical, with hypopigmented areas.
• A multi-component pattern is a combination of 3 or more patterns and may signify a higher possibility of melanoma.
• Nevi located on special sites exhibit distinctive clinical, dermatoscopic, and histopathological features of which the clinician should be aware. For example, nevi of the face may show a pseudo-network pattern secondary to prominent follicular units, and acral nevi exhibit a parallel furrow pattern in which pigment is accentuated in the narrow furrows of the dermatoglyphs. Age, skin type, ultraviolet light exposure, pregnancy, and growth dynamics also influence the dermatoscopic findings of melanocytic nevi.

Question 25

mx of melanoma

Answer 25

excision biopsy
sentinal node mapping
isolated limb perfusiona nd block dissection of regional LN groups