Pigmented Skin Lesions

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Pigmented Skin Lesions

• MELANOMA

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MELANOMA

• Malignant melanoma is a skin cancer due to
  uncontrolled growth of pigment cells
  -melanocytes.

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Melanocytes

• Normal melanocytes occur in the basal layer of
  the epidermis
• They produce melanin
• Melanin (a protein) protects the skin by
  absorbing ultraviolet (UV) radiation
• Melanocytes are found in equal numbers in black
  and in white skin
• Melanocytes in black skin produce much more
  melanin
• Non-cancerous growth of melanocytes results in
  moles (benign melanocytic naevi) and freckles
• Cancerous growth of melanocytes results in
  melanoma

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Risk Factors for Melanoma

• Sun exposure, particularly during childhood
• Fair skin that burns easily
• Blistering sunburn, especially when young
• Previous melanoma
• Previous non-melanoma skin cancer (BCC, SCC)
• Family history of melanoma
• Large numbers of moles (esp if gt 100)
• Abnormal moles (atypical or dysplastic naevi)

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Epidemiology of Melanoma

• 3 of all cancers and 10 of skin cancers.
• Incidence 110,000 per annum
• Incidence is increasing in developed countries
• Incidence rises with age, rare in children,
  commonest in over 75s
• 3rd commonest cancer in young people.
• In UK 2002 - 1,640 deaths from malignant melanoma
  Over 65 of deaths from malignant melanoma were
  in the over 65s.
• It is commoner in women than in men but men have
  a worse prognosis.

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Melanoma in situ

• Superficial forms of melanoma spread out within
  the epidermis (horizontal growth).
• If all the melanoma cells are confined to the
  epidermis, it is melanoma in situ.
• Lentigo maligna is a special case of melanoma in
  situ that occurs around hair follicles on the sun
  damaged skin of the face or neck.
• Melanoma in situ is cured by excision

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Invasive Melanoma

• When the cancerous cells have grown through the
  basement membrane into the deeper layer of the
  skin (the dermis), it is known as invasive
  melanoma (vertical growth)
• Nodular melanoma appears to be invasive from the
  beginning, and has little or no relationship to
  sun exposure.
• Metastatic disease increases in likelihood with
  increasing depth of the melanoma.
• 15 of people with invasive melanoma will die
  from it.

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Where do melanomas occur?

• Melanoma can arise from otherwise normal
  appearing skin (50)
• Or from within a mole or freckle, which starts to
  grow larger and change in appearance. Precursor
  lesions include
• Congenital melanocytic naevus (brown birthmark)
• Atypical or dysplastic naevus (funny-looking
  mole)
• Benign melanocytic naevus (normal mole)
• Melanomas occur anywhere on the skin, not only in
  sun-exposed areas. Commonest sites men - back
  (40), women - leg (40).
• Melanomas can also occur on mucous membranes
  (lips, genitals).
• May also occurs in other parts of the body such
  as the eye, brain, mouth or vagina.

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Moles (Melanocytic Naevi)

• Very common
• May be flat or protruding
• Vary in colour from pink to black
• Brown or black coloured moles are also called
  pigmented naevi.
• Mostly round or oval in shape
• Range in size from 2mm to several cm

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Moles

• Most frequently moles arise during childhood or
  early adult life (acquired melanocytic naevi).
• Exposure to sunlight increases the number of
  moles.
• Teenagers and young adults tend to have the
  greatest number of moles.

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Classification

• Junctional naevi
• Groups or nests of naevus cells at the junction
  of the epidermis and dermis. Tend to be flat
  colourful moles.
• Dermal/Intradermal naevi
• Nests of naevus cells in the dermis. These moles
  are thickened and often protrude from the skin
  surface (papillomatous naevi).
• Compound naevi
• Nests of naevus cells at the epidermal-dermal
  junction as well as within the dermis. These
  moles have a central raised area surrounded by
  flat pigmentation.

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Junctional Naevus

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Congenital Melanocytic Naevus

• Brown or black naevi
• Present at birth or develop in the first year or
  so of life
• Moles that look like birthmarks but were not
  present at birth may be called congenital
  naevus-like naevi or congenital-type naevi.
• About one baby in 100 has a small or medium sized
  congenital naevus, so they are quite common.
• Very large, giant or bathing trunk naevi are very
  rare.

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Types of congenital melanocytic naevus

• Typically multi-shaded, oval, fairly uniform
  pigmented patches
• Most grow with the child but become
  proportionally smaller and less obvious with
  time.
• May darken, become bumpy or hairy especially at
  puberty.
• Rarely fade away or disappear.
• Congenital melanocytic naevi in adults are
  classed as small (lt 1.5cm di), medium (gt1.5
  lt10cm) or large (gt10cm)
• Giant congenital naevi are greater than 20cm in
  diameter. Often found on the buttocks (bathing
  trunk naevi)
• Café-au-lait macule - a flat tan mark, usually
  oval (inherited). Multiple café-au-lait macules
  may be a sign of neurofibromatosis.
• Speckled lentiginous naevus (naevus spilus) has
  dark spots scattered on a flat tan background.

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Risk of Melanoma

• The risk of melanoma in a small or medium-sized
  congenital melanocytic naevus is very small (lt
  1)
• Melanoma never arises from café-au-lait macules
• Melanoma is more likely in the giant naevi ( 5
  over a lifetime) especially in those that lie
  across the spine

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Congenital Melanocytic Naevus

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Café au lait Macule

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Giant Melanocytic Naevus

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Speckled Melanocytic Naevus

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Atypical Naevi

• Melanocytic naevi with unusual features eg
  indistinct edge, larger size.
• May resemble Malignant Melanomoa but are benign
• Sometimes called dysplastic naevi, active
  junctional naevi, B-K moles and Clark's naevi.
• May be familial or sporadic.
• The inherited form is usually part of a syndrome
  - Familial Atypical Mole and Melanoma (FAMM)
  syndrome (formerly dysplastic naevus syndrome).
• One or more first-degree or second-degree
  relative with malignant melanoma
• A large number of naevi (often more than 50) some
  of which are atypical naevi
• Naevi that show certain histological features.

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Atypical Naevi

• Fair-skinned individuals with light coloured
  hair and freckles are most at risk of getting
  atypical naevi, especially if they have been
  frequently exposed to the sun or have a family
  history of atypical naevi.
• Atypical naevi may develop at any time but most
  develop during the first 15 years of life.

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Atypical Naevi

• People with one to four atypical naevi have a
  slightly higher risk than the general population
  of developing malignant melanoma
• People with FAMM syndrome are significantly more
  at risk of developing melanoma.
• Atypical naevi are harmless (benign) and do not
  need to be removed. However, it is not always
  easy to tell whether a lesion is an atypical
  naevus or a melanoma, so if in doubt, it should
  be removed by excision biopsy.

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Atypical Naevus

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Atypical Naevus

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Glasgow 7-point Checklist

• Major features
• Change in size
• Irregular shape
• Irregular colour
• Minor features
• Diameter gt7mm
• Inflammation
• Oozing
• Change in sensation

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ABCDE of Melanoma

1. Asymmetry
2. Border - irregularity
3. Colour - variation
4. Diameter - over 6 mm
5. Evolving - (enlarging, changing)

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Types of Melanoma

• Flat patches (horizontal slow growth)
• Superficial spreading melanoma (SSM)
• Lentigo maligna melanoma (sun damaged skin of
  face, scalp and neck)
• Acral lentiginous melanoma (on soles of feet,
  palms of hands or under the nails the subungual
  melanoma)
• Nodules (vertical rapid growth)
• Nodular melanoma
• Mucosal melanoma (arising on lips, eyelids,
  vulva, penis, anus)
• Desmoplastic melanoma (fibrous tumour with a
  tendency to grow down nerves)
• Combinations occur e.g. nodular melanoma arising
  within a superficial spreading melanoma.

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Typical Superficial Spreading Melanoma

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Superficial Spreading Melanoma with regression

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Amelanotic Melanoma

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Lentigo Maligna

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Lentigo Maligna Melanoma

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Lentigo Maligna

• Sun-exposed areas of the face and neck
• Elderly
• Slow growing
• Often quite large (gt20mm).
• Pre-cancerous
• Conversion to a lentigo maligna melanoma occurs
  in 5 of patients
• Identifying lesions that require referral is not
  easy but see ABCDE

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Nodular Melanoma in Lentigo Maligna

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Acral Lentiginous Melanoma

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Subungual Melanoma

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Amelanotic Subungual Melanoma

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Nodular Melanoma

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Nodular Melanoma

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Nodular Melanoma

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Diagnosis

• Excision biopsy with a 2 to 3-mm margin
• Breslow depth - thickness of the melanoma in mm
• Clark's level - describe which layer of the skin
  has been breached. Clarks level 1 refers to
  melanoma in situ. Invasive melanoma may reach
  Clark's level 2 (thin) to 5 (reaching the
  subcutaneous fat layer).
• Systematic search for metastasis

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Prognosis

• Death is unlikely if a melanoma has a Breslow
  thickness of less than 1mm
• 50 dead within 5 years if gt4mm