Malignant melanoma and metastases

Melanoma is a tumor that develops in the melanocytes, the pigment cells of the skin.

It can be more aggressive than other types of skin cancer because it can spread elsewhere in the body (metastases) and also lead to death.


Types of melanoma

  • Superficial spreading melanoma (65-70% of cases)
  • Nodular melanoma (10-15% of cases)
  • Lentigo malignant melanoma
  • Acral-lentiginous melanoma
  • Some very rare types of melanoma

Superficial spreading melanoma
This is the most common melanoma.
It grows mainly outwards, rather than into the depths of the skin.

  • Slow spread
  • Horizontal or radial growth

Usually, superficial spreading melanoma is:

  • at the initial stage, not the risk of spreading to other parts of the body,
  • but over time, growth can begin in deeper layers of the skin.

Anyone who has a nevus that increases in size and has an irregular edge should have a medical check-up.

Nodular melanoma This type of melanoma
develops quite quickly in the dermis, the deep layer of the skin.
It is the most aggressive form of melanoma and diagnosis is often delayed.
It occurs frequently:

  • Breast
  • Back
  • Neck
  • Head.

If it is not removed, it begins to grow inwards into deeper layers of the skin and spreads quite quickly to the surrounding lymph nodes and tissues.
In this type of melanoma, a raised zone is often observed on the surface of the skin.
Nodular melanoma does not cause pain.

Characteristic of this melanoma are also:

  • dome shape,
  • rapid altitude growth,
  • touching,
  • tendency to ulceration and bleeding,
  • dark brown to black color, can also be pink or red.

It develops from slow-growing pigmented patches of skin (spots), also called lentigo maligna or melanotic spot of Hutchinson.
It is more common in the elderly.
It appears on sun-exposed skin, for example on the face.
The lentigo maligna:

  • is flattened,
  • develops outwards in the superficial layers of the skin.

If it becomes lentigo-malignant melanoma:

  • it grows slowly (over the course of 10-20 years) inwards into the deeper layers of the skin,
  • can form nodules.

Acral-lentiginous melanoma Acral-lentiginous melanoma
is rare and occurs mainly:

  • palms,
  • under the soles of the feet,
  • around the big toenail;
  • it can also grow under the nail.

It is more common on feet than hands and prefers people with dark skin between 50 and 70 years of age.

Other types of melanoma

Amelanotic melanoma
Amelanotic means without melanin.
Melanomas are dark in color, while the amelanotic ones have little or no color. Sometimes they are:

  • pink or red,
  • tan
  • gray at the edges.

They are treated in the same way as other melanomas.

Melanoma elsewhere
Melanoma can occur anywhere on the body, including internal organs.

Melanoma of the eye or choroidal melanoma Rarely, melanoma
can also develop within the eye. One meets melanocytes:

  • in the iris (the colored area around the pupil),
  • in the choroid (vessel-rich layer of the skin of the eye).

When these melanocytes (cells that produce melanin) become malignant, they are called melanoma.
If the melanoma develops on the iris, a dark spot can be observed on it.
People with light eyes (light skin type) have an increased risk of this type of melanoma.

Mucosal melanoma
Melanocytes are also present in the mucous membranes. For this reason, melanomas can also develop in areas such as:

  • Mouth
  • Mucous membrane inside the nose.

Other, rare mucosal tumors are:

  • melanoma of the vulva,
  • melanoma of the vagina,
  • Melanoma of the rectum.

Classification according to growth of melanoma

Doctors use a Breslow or Clark classification to describe the prognosis. The interpretation is as follows:

Tumor thickness according to Breslow
The thickness according to Breslow is defined as the total vertical height of the melanoma:

  • from the granule cell layer of the epidermis
  • to the point of maximum infiltration.

For this purpose, an instrument, the so-called eyepiece micrometer, is used to measure the thickness of the removed tumor.
Basically, the higher the Breslow thickness, the worse the prognosis: The thickness is an indicator of the risk of spreading the tumor.
The thickness of the melanoma is directly related to the survival rate (survival rates are averages and cannot be related to the individual case):

  1. Level I: < 1 mm, the tumor is defined as “thin”, the survival rate after 5 years is 90% to 95%.
  2. Level II: 1-2 mm, the survival rate after 5 years is 80% to 96%.
  3. Level III: 2.1-4 mm, survival rate after 5 years is 60% to 75%.
  4. Level IV: > 4 mm, the survival rate after 5 years is 45% to 63%.

Breslow’s thickness is one of the three most important prognostic factors in melanoma, along with:

  • Tumor stage ,
  • Presence of ulceration (skin lesions, bleeding, swelling).

Clark classification
The Clark stage refers to tumor penetration into the depth of the skin layers.
This system was originally developed by W. H. Clark in 1966.
Officially, the following stages are defined according to Clark:

  1. Stage I: limited to the epidermis (upper layer of the skin). Called in situ melanoma with a cure rate in this phase of 100%;
  2. Stage II: invasion into the papilla layer of the dermis (superior);
  3. Stage III: filling the papillae layer, but without expanding into the stratum reticular (inferior);
  4. Stage IV: invasion into the stratum reticulare;
  5. Stage V: Invasion into the deep subcutaneous tissue.

Mitotic index
Mitotic index (or mitotic stage index) indicates the percentage of cancer cells that are currently growing or dividing (mitosis).
A high mitotic index means a high probability that the cancer will grow and spread.
The mitotic index is particularly helpful in the staging of small melanomas (< 1 mm), which are usually classified as low-risk.

Determination of the stages of melanoma

The staging includes all diagnostic parameters.

  • Stage 0: In situ melanoma
  • Stage I: < 1 mm thick
    • A: low-risk invasive melanoma, without ulceration or mitosis
    • B: low-risk invasive melanoma, with ulceration and mitosis
  • Stage II: 1 – 4 mm thick
    • A: without ulceration
    • B: with ulceration
  • Stage III: extensive tumor with micrometastases in the lymph nodes
  • Stage IV: extensive tumor with widespread metastases in different areas of the body

Causes of melanoma

It is not known what damages the DNA in the melanocytes and leads to the development of melanoma.
There is probably a combination of genetic and environmental factors that cause melanoma.

Factors that increase the risk of melanoma include:

  • Light skin. Less pigment (melanin) in the skin means having less protection against damaging UV rays.
  • Past sunburns. A burn blister from sunburn can increase the risk of melanoma in children and adults.
  • Long stay in the environment with ultraviolet rays (UVA and UVB). UV rays coming from the sun or tanning lights can increase the risk of skin cancer, including melanoma.
  • Living near the equator or in the mountains.
  • Many moles, freckles or unusual birthmarks. More than 50 moles on the body mean a higher risk of developing melanoma.
  • family history of melanoma. If a parent, child or sibling has had melanoma, there is an increased likelihood of developing a tumor.
  • Weakened immune system. People with weakened immune systems carry an increased risk of melanoma. For example:
    • People with AIDS
    • People who have undergone organ transplantation.

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