Melanoma

Abnormal cells are found only in the top (outer) layer of skin (epidermal) and have not invaded deeper tissue (dermis or subcutaneous fat). This is termed melanoma in situ.

Stage IA
Cancer invades the superficial portion of the inner layer of skin (dermis), is not ulcerated, has a low mitotic rate (less than 1/mm2), and it has not spread to nearby (regional) lymph nodes. The tumor is less than or equal to 1.0 millimeter in thickness.

Stage IB
The tumor is less than or equal to 1.0 millimeter thick and is ulcerated, or has a high mitotic rate (≥1/mm2), or it is 1.01-2.0 millimeters in depth and not ulcerated. It is only in the skin, and has not spread to nearby lymph nodes. Staging of the regional lymph nodes is generally recommended for skin melanomas that are Stage IB and deeper. This is done through a procedure called the Sentinel Lymph Node Biopsy.

Stage IIA
The melanoma has invaded the lower part of the inner layer of skin (dermis), but not into the tissue below the skin (the subcutaneous fat) or into nearby lymph nodes. The tumor is 1.0-2.0 millimeters and ulcerated or 2.0-4.0 millimeters and not ulcerated.

Stage IIB
The melanoma is 2.01-4.0 millimeters thick and ulcerated, or greater than 4.0 millimeters and not ulcerated. It is only in the skin, and not in nearby lymph nodes.

Stage IIC
The tumor is greater than 4.0 millimeters thick and ulcerated, but only involves the skin and not regional lymph nodes.

Stage IIIA
The melanoma is not ulcerated on the skin, but has spread to one to three nearby lymph nodes microscopically and the nodes are not enlarged (palpable). There is no distant spread.

Stage IIIB
The melanoma on the skin is ulcerated and has spread to one to three nearby lymph nodes, but the nodes are not enlarged. There is no distant spread.
OR
The skin melanoma is not ulcerated and has spread to one to three nearby lymph nodes and the nodes are enlarged. There is no distant spread.
OR
The melanoma may or may not be ulcerated and has spread to nearby skin or lymph channels (intralymphatic metastasis, also termed satellite or in-transit disease), but it is not in the regional lymph nodes, and there is no distant spread.

Stage IIIC
The tumor is ulcerated and has spread to one to three nearby lymph nodes which are enlarged. There is no distant spread.
OR
The skin melanoma may or may not be ulcerated and has spread to four or more nearby lymph nodes or to clumped (matted) lymph nodes or to nearby skin, lymph channels (in-transit disease), and nodes. The nodes are enlarged (palpable), but there is no distant spread.

The tumor has spread to other organs, or to skin or lymph nodes far away from the original tumor. Substages for distant disease depend on:

1. Anatomic sites of involvement (distant skin, subcutaneous tissue, or lymph nodes vs. lungs alone vs. all other distant sites) 
2. Presence or absence of elevated lactate dehydrogenase (LDH) in the blood