Staging and grade
Cancer staging is a term used to refer to describing the tumor's size and whether or not it has spread beyond the area where it began.
Staging systems are constantly being updated to be able to help doctors plan the best treatment and help give them an idea of the probably outcome of treatment.
The mitotic index describes the number of cells within a particular amount of melanoma tissue found to be in the process of dividing. A higher mitotic index means the cancer has a higher risk of spreading.
The melanoma is no bigger than 2 mm, is found only in the skin and has not spread to any other parts of the body.
Stage 1A: The melanoma is 1 mm thick or less, has no ulceration, and has a mitotic index of under 1 mm².
Stage 1B: The melanoma is 1 mm thick or less, shows ulceration, or has a mitotic index of at least 1 mm². Alternatively, the melanoma is between 1.01 and 2 mm in thickness though shows no ulceration.
The melanoma has not spread into the lymph nodes or other parts of the body.
Stage 2A: The melanoma is between 1.01 and 2 mm in thickness and shows ulceration. Alternatively, the melanoma is between 2.01 and 4 mm in thickness and shows no ulceration.
Stage 2B: The melanoma is between 2.01 and 4mm in thickness and shows ulceration. Alternatively, the melanoma is thicker than 4 mm but without ulceration.
Stage 2C: The melanoma is thicker than 4 mm or has ulceration.
The melanoma has spread into the nearby lymph vessels or nodes but not to other parts of the body. Thickness is not a determining factor, though the melanoma is usually thick. This stage is subdivided into stages 3A, 3B, and 3C depending on such factors as:
- The number of lymph nodes involved
- Whether the lymph node involvement is macroscopic or microscopic.
- Whether the melanoma cells are in the skin or lymph vessels near the melanoma.
The melanoma has spread to other areas of skin that are distant from the original site or lymph nodes or to other organs such as the lung, liver, or brain. Metastatic melanoma.
When melanomas are classified, a scale is also used to measure the thickness (depth) of the melanoma. This is called the Breslow thickness.
The extent to which the melanoma cells have grown down into the deeper layers of skin is measured in millimeters (mm).
Most patients have melanomas that are 1 mm thick or less. These are classified as stage-1 or thin melanomas. It is rare for these to spread and most can be cured by a simple operation called local excision.
If the melanoma is thick, it is more likely to spread to the nearest lymph vessels. If this happens, additional surgery will be necessary to remove the lymph nodes that have been affected in addition to the melanoma itself.
In situ melanoma
In situ melanoma is a term used to describe the very early stage of a melanoma. It is also called melanocytic intraepithelial neoplasia.
The melanoma cells are only on the uppermost layer of the skin (epidermis) and have not spread down into the dermis. As they are only in the epidermis, there is usually no risk of the melanoma spreading to other parts of the body.