Malignant melanoma

• Malignant melanoma:

  • Cancerous growth of melanocytes
  • 5th most common cancer in the UK
• Cause:

  • Results from a combination of environmental and genetic risk factors
  • UV light exposure
  • Severe sun burn in childhood
  • Immunosuppression
  • Multiple (>100) or giant (>20cm) naevi
  • Fitzpatrick skin types I + II
  • Family history
  • Certain genetic mutations
• Presentation:

  • Usually appear as a pigmented lesion with an irregular border that often grows/changes
  • Most arise de novo but they can occur within an existing lesions e.g. melanocytic naevi, solar lentigo
  • Features suspicious of melanoma can be remembered using the mnemonic ABCDE:
  • Asymmetry
  • Border - irregular
  • Colour alterations
  • Diameter >6mm
  • Evolving lesion
• NICE recommends the weighted 7-point checklist:

  • Refer if score 3 or more
  • Major features (2 points each) = change in size, shape, or colour
  • Minor (1 point each) = diameter 7cm or more, oozing, change in sensation (including itch)
• Superficial spreading:

  • Most common type
  • Occurs in any location
• Nodular:

  • Second most common type
  • Most aggressive type
  • Presents as a nodule that grows rapidly
  • Often bleed or ulcerate
• Lentigo maligna:

  • Occurs in elderly on chronically sun exposed sites
  • Takes longer to grow and metastasise so typically better prognosis
• Acral lentiginous:

  • Type of melanoma that originates on the palms, soles or under the nails - presenting as a flat pigmented lesion that slowly enlarges
  • Diagnosis often delayed
  • Sub type of subungual melanoma - appears as a dark vertical streak on the nail
• amelanotic melanoma is a form of melanoma in which the malignant cells possess little or no pigment- described as skin coloured- any subtypes of melanoma can be amelanotic
• Management of suspicious lesions:

  • Referral to dermatology via 2WW pathway
  • Assessed with dermoscopy and if concerning will arange excisional biopsy
  • Lesion will be completely excised with a 1-2mm margin of healthy surrounding skin
  • May have a smaller punch biopsy if very large legion or close to vital structures e.g. eye
• Management of confirmed melanoma:

  • Local disease is usually treated with wide local excision - size of excision margin guided by thickness of lesion
  • Any suspicious lymph nodes require fine needle aspiration and cytology
  • If high risk lesion or proven lymph node spread consider whole body imaging
• Prognosis is guided by:

  • How deep the melanoma is spreading - Breslow thickness - thicker the melanoma the more likely it will metastasise
  • How fast its growing - mitotic rate
  • Whether it is ulcerated - correlates with poorer prognosis
• Staging:

  • TNM
  • AJCC (American joint committee on cancer) - stage 0 to 4
  • Common sites of metastasis - regional lymph nodes, liver, lungs, bone, brain
• Options for management:

  • Wide local excision
  • Sentinel lymph node biopsy - staging tool and to excise lymph node
  • Chemotherapy - generally not affective
  • Radiotherapy
  • Immunotherapy - increase immune system response to respond to and destroy cancer cells
  • Targeted therapy e.g. monoclonal antibodies that target cancer cells