Melanoma & Other Skin Cancers

Diagnosis and Staging

A biopsy must be done to confirm the diagnosis of a non-melanoma or melanoma. An excisional biopsy or a deep-shave biopsy is most often used if the lesion is thought to be melanoma, as this method involves excision (removal) of the entire lesion.

The factors considered in classifying the melanoma according to the tumor (T) staging category in the AJCC system are the thickness of the lesion and the presence or absence of ulceration. (Ulceration means that the layer of skin over the melanoma is disrupted.)

The T categories are as follows:

Tx: Melanoma cannot be evaluated (because of lack of information)
T0: No cancer is found
Tis: Melanoma cells are found in only the outer layer of skin, but have not yet invaded into the next layer (the dermis) of the skin (also known as melanoma in situ)
T1: Melanoma is no more than 1 mm thick
T2: Melanoma is more than 1 mm thick but no more than 2 mm thick
T3: Melanoma is more than 2 mm thick but no more than 4 mm thick
T4: Melanoma is more than 4 mm thick

Each T classification is also subcategorized according to whether ulceration is absent (subcategory a) or present (subcategory b). For example, an ulcerated lesion that is 1 mm thick is classified as T1b. The pathologist will also report on the level of invasion, a measure of how deep into the dermis the melanoma has invaded.

The node (N) classification is used to describe the spread of the melanoma to lymph nodes in terms of both the number of lymph nodes involved and the amount of cancer cells in the lymph nodes. If the cancer cells in the lymph node are found with use of a microscope, the metastasis is considered to be microscopic. If there are enough cancer cells in the lymph node to make the node appear as a palpable mass, it is said to be macroscopic.

The N categories are as follows:

Nx: Lymph nodes cannot be evaluated (because of lack of information)
N0: No spread of melanoma to lymph nodes
N1: Melanoma found in one lymph node
N2: Melanoma found in two or three lymph nodes
N3: Melanoma found in four or more lymph nodes or two or more lymph nodes appear to be joined together (known as matted lymph nodes)

The N1, N2 and N3 categories include subcategories to indicate whether metastasis to the lymph nodes is microscopic; that is, not clinically detectable (subcategory a); or macroscopic; that is, detectable by clinical or x-ray exam (subcategory b). In addition, N2 and N3 also include a subcategory of c to indicate in-transient or satellite metastasis, which is the presence of cancer cells in the lymphatic vessels leading to a lymph node.

Lastly, the melanoma is classified according to whether the cancer has metastasized.

The M categories are as follows:

Mx: Metastasis cannot be evaluated (because of lack of information)
M0: No metastasis
M1: Metastasis
M1a: Melanoma has spread outside the region where it first started to other parts of the skin, under the skin, or any distant lymph nodes;
M1b: Melanoma has spread to the lungs
M1c: Melanoma has spread to any other internal organ in the body.


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