3. MALIGNANT MELANOMA

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3. MALIGNANT MELANOMA

• A tumour arising from melanocytes of the basal
  layer of the epidermis
• Less commonly uveal tract (eye) and meningeal
  membranes

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INCIDENCE

• Global incidence is rising relentlessly
• In NI, the incidence rate of melanoma is
  increasing faster than any other tumour
• 1996 181 new cases of malignant melanoma
• On average 28 deaths due to melanoma each year

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RISK FACTORS FOR MELANOMA

• Large numbers of benign naevi
• Freckles
• Clinically atypical naevi
• Severe sunburn
• Early years in a tropical climate
• Family history of MM

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PATIENT EDUCATION
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FAMILY HISTORY

• The majority of MMs occur in a sporadic pattern
• 2-10 of patients presenting with MM give a
  positive family history
• In part this may be due to the inheritance of
  specific MM susceptibility genes eg, CDKN2A on
  chromosome 9
• Other reasons for familial clustering are
  atypical naevi and sun exposure

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NAEVI

• CONGENITAL NEVI occur in 1 of newborns. Tend
  to be large. Increased risk of MM
• ACQUIRED MELANOCYTIC NAEVI 30-50 of all MMs
  arise in pre-existing naevi. ?nos of naevi?risk
  MM
• ATYPICAL NAEVI / SYNDROME association between a
  familial occurrence of MM and an atypical naevus
  phenotype

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SUNSCREENS

• Have been promoted as protective agents
• But this is not supported by epidemiological data
• ? Causal role of sunscreen chemicals
• ? False sense of security in those at risk
  spend longer out doors but dont reapply
  appropriately

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AIDS IN CLINICAL DIAGNOSIS

• GLASGOW SYSTEM
• Major
• Change in size
• Irregular pigment
• Irregular outline
• Minor
• Diameter gt6mm
• Inflammation
• Oozing/bleeding
• Itch/altered sensation

• AMERICAN ABCDE
• SYSTEM
• Asymmetry
• Border
• Colour
• Diameter
• Examination

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TYPES OF MELANOMA
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NODULAR

• Commoner in males
• Trunk is a common site
• Usually thick with a poor prognosis
• Black/brown nodule
• Ulceration and bleeding are common

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SUPERFICIAL SPREADING

• The most common type of MM in the white-skinned
  population 70 of cases
• Commonest sites lower leg in females and back
  in males
• In early stages may be small, then growth becomes
  irregular

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ACRAL LENTIGINOUS MELANOMA

• In white-skinned population this accounts for 10
  of MMs, but is the commonest MM in
  nonwhite-skinned nations
• Usually comprises a flat lentiginous area with an
  invasive nodular component

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SUBUNGAL MELANOMA

• Rare
• Often diagnosed late confusion with benign
  subungal naevus, paronychial infections, trauma
• Hutchinsons sign spillage of pigment onto the
  surrounding nailfold

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LENTIGO MALIGNA MELANOMA

• Occurs as a late development in a lentigo maligna
• Mainly on the face in elderly patients
• May be many years before an invasive nodule
  develops

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AMELANOTIC MELANOMA

• Diagnosis is often missed clinically
• The lack of pigmentation is due to the rapid
  growth of the tumour and the differentiation of
  the malignant melanocytes

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METASTATIC MELANOMA
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PROGNOSTIC VARIABLES

• The Breslow thickness is the single most
  important prognostic variable (distance in mm of
  the furthest tumour cell from the basal layer of
  the epidermis)

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• Scalp lesions worse prognosis, then palms and
  soles, then trunk, then extremeties
• Younger women appear to do better than either men
  at any stage or women over 50
• Ulceration of the tumour surface is a high risk
  factor

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MANAGEMENT

• Surgical excision 1-3cm margins depending on
  breslow depth
• Invasive primary MM on the digits can be treated
  by amputation
• Need to investigate all MMs over 1mm for
  metastases CXR, USS abd or CT chest, abd,
  pelvis, bloods FBP, LFTs, LDH
• New scanning modality in Belfast PET scan for
  high risk primaries or evaluating lymphadenopathy

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FOLLOW UP

• No general agreement on time period
• Depends on tumour thickness
• Thick tumours 5-10 years
• Need to examine the scar and check for
  lymphadenopathy, liver, spleen, and total body
  examination for other suspicious naevi

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PLANTAR MALIGNANT MELANOMA

• Caucasians 1-9
• Asians 29-46
• Afro-Carribean 60-70

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SUBUNGAL MELANOMA
TRAUMA
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Dwyer PK et al British Journal of Dermatology
1993128115-120

• 51 white caucasian patients west of Scotland with
  plantar melanoma
• 20 sup spreading melanoma
• 27 acral lentiginous
• 4 nodular
• Femalemale 32

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Franke W et al Melanoma Research 200010571-576

• Prognosis for plantar melanoma poor
• Poor survival can be improved by a significant
  reduction in the time period between the first
  observation of a plantar skin lesion and surgical
  treatment

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Walsh SM et al The Journal of Foot and Ankle
Surgery 200342(4)193-198

• ..that the clinician must maintain a high index
  of suspicion when a patient presents with a
  pigmented or atypical lesion on the foot.