Melanoma
Melanoma
Melanoma

Melanoma

Malignant melanoma is a potentially serious type of skin cancer.

This needs to be diagnosed and treated early to improve survival rates.

Depending on the size and site of the melanoma you may be offered a wide excision and biopsy of the suspected melanoma at Palm Clinic or referral to a plastic surgeon.

Southern Cross Health Society

Palm Clinic is an Affiliated Provider to Southern Cross Health Society for skin cancer treatment, skin biopsies, and skin cancer surgery. Medical necessity criteria apply.

Frequently Asked Questions

Who is at risk of melanoma?

Melanoma is most common in pale skinned people, but it may rarely develop in those with dark skin as well. About one in fifteen Pakeha New Zealanders are expected to develop melanoma in their lifetime – New Zealand and Australia have the highest reported rates of melanoma in the world. Melanoma is the third most common cancer in New Zealand females and the fourth most common cancer for males.

Melanoma can occur in adults of any age but is very rare in children. New Zealand statistics in 2003 showed:

  • Fewer than 1% occurred under 20 years old
  • 13% occurred at 20 to 40 years old
  • 36%  aged 40 to 59 years old
  • 51% over 60 years old

Unfortunately, about 15% of those with invasive melanoma die from it; around 250 New Zealanders die from melanoma each year. The main risk factors for developing melanoma are:

  • Fair skin that burns easily
  • Blistering sunburn especially when young
  • Previous melanoma
  • Previous non-melanoma skin cancer (BCC/SCC)
  •  Family history of melanoma, especially if two or more members are affected
  • Large numbers of moles (especially if there are more than 100)
  • Abnormal moles –dysplastic naevi syndrome

How does a melanoma grow?

Cancers grow at an uncontrolled rate because of abnormalities in the genes that control cell growth. Further genetic changes promote invasion into surrounding tissue. Melanoma is now thought to begin as uncontrolled proliferation of transformed melanocytic stem cells.

Superficial forms of melanoma spread out within the outside layer of skin (the epidermis). A pathologist may report this as the radial or horizontal growth phase. If all the melanoma cells are confined to the epidermis, it is melanoma in situ. Lentigo maligna is a special kind of melanoma in situ that occurs around hair follicles on the sun damaged skin of the face or neck. Melanoma in situ is always cured by excision because it has no potential to spread round the body.

When the cancerous cells have grown into the deeper layer of the skin (dermis), it is known as invasive melanoma. Histology from the excision will state that the tumour has a vertical growth phase, which is potentially more dangerous than the horizontal growth phase. Nodular melanoma is different in that it appears to be invasive from the beginning, and has little or no relationship to sun exposure.

Once the melanoma cells have reached the dermis, they may spread to other tissues via the lymphatic system to the local lymph nodes or via the blood stream to other organs such as the lungs or brain. This is known as metastatic disease or secondary spread. The chance of this happening mainly depends on how deep the cells have penetrated into the skin. Hence the need for early detection.

Where on the body do melanomas grow?

Melanoma can arise from normal appearing skin (50% of melanomas) 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 ( multiple irregular variegated coloured moles)
  • Benign melanocytic naevus (normal mole)

Melanomas can occur anywhere on the body, not only in areas that get a lot of sun. The most common site for men is the back (around 40% of melanomas), and the most common site for women is the leg (also around 40%).

Although melanoma usually starts as a skin lesion, it can also grow on mucous membranes such as the lips or genitals. Occasionally it occurs in other parts of the body such as the eye, brain, mouth or vagina.

What do melanomas look like?

The first sign of a melanoma is usually a changed or new freckle or mole. It may have an unusual shape. A melanoma may be detected at an early stage when it is only a few millimetres in diameter, but they may grow to several centimetres in diameter.

It may have a variety of colours including tan, dark brown, black, blue, red and, occasionally, light grey. Melanomas that are lacking pigment are called amelanotic melanoma. During the horizontal growth phase, a melanoma is normally flat. As the vertical phase develops, the melanoma becomes thickened and raised.

Some melanomas are itchy or tender. More advanced lesions may bleed easily or crust over. Any mole with the following characteristics should be checked by a doctor immediately:

  • Asymmetry
  • Border is uneven
  • Colour variation
  • Diameter greater than 6mm
  • Evolving – any change in size, shape colour or new symptoms such as bleeding, itching crusting