Table 1. Classification of Cutaneous Melanoma According to TNM.

Melanoma stage	Description
0 (in situ)	Only the outer or top layer of skin cancer cells.
IA	The tumor is > 0.8 mm but < 1 mm with possible ulceration or without ulceration; the tumor is 0.8 mm thick or less.
IB	The tumor, without ulceration, is > 1 mm but < 2 mm thick.
IIA	The tumor is > 2 mm thick but < 4 mm thick without ulceration or with ulceration, the tumor is > 1 mm thick but < 2 mm thick.
IIB	The tumor is > 2 mm thick with ulceration but < 4 mm thick, or the tumor is > 4 mm thick without ulceration.
IIC	With ulceration, the tumor is more than 4 mm thick.
III	The spread of cancer to one or more lymph nodes close to the initial disease site.
IV	Cancer, also called metastatic melanoma, has spread to other body areas, such as the liver and lungs.

TNM: tumor-node-metastases.