Melanoma diagnosis and staging

Diagnosis

Because no two people develop skin cancer in the same way, we offer a wide array of resources for proper evaluation of your situation—and we use that information to create a personalized plan to fit your specific needs.

Once a cancer has been diagnosed, our specialists need to know where it may have spread. This is the “stage” of the cancer. The lower the number, the less it has spread. Knowing the stage allows us to determine the best possible treatment plan for you.

We may use any combination of these tests and procedures to diagnose and stage skin cancer:

  • Biopsy. Removes all or part of the abnormal-looking skin growth for viewing under a microscope by an expert skin pathologist to check for signs of cancer.
  • CT scan (computed tomography). Uses a type of X-ray to create detailed, highly accurate, cross-sectional images to establish staging.
  • Dermoscopy. Uses a drop of mineral oil on the lesion to reduce light reflection, make the skin more translucent, and assist in viewing skin lesions to accurately distinguish between suspicious moles and other pigmented lesions.
  • Epiluminescence microscopy. Allows viewing of a lesion down to the dermo-epidermal junction—the areas where melanomas usually develop—that’s not visible to the naked eye.
  • Excisional biopsy. Uses a scalpel to remove the entire growth.
  • Mole mapping. Uses a full-body photograph and digital analysis to identify mole locations and different features as a way to help determine which moles need to be removed; also used to detect new moles and subtle changes in existing moles between visits.
  • Magnetic resonance imaging (MRI) scan. Like CT scans, MRI scans show detailed images of soft tissues in the body.
  • Positron emission tomography (PET) scan. A PET scan can look for possible areas of cancer spread in all areas of the body at once.
  • Punch biopsy. Uses a special instrument called a punch to remove a circle of tissue from the abnormal-looking growth.
  • Sentinel lymph node biopsy. A surgical procedure used to determine whether cancer has spread into the lymphatic system
  • Skin examination. Uses a visual check of the skin for bumps or spots that look abnormal in color, size, shape, or texture.

UCHealth follows the the American Joint Committee on Cancer (AJCC) TNM system for staging melanoma, which is based on three key pieces of information:

  1. The extent of the primary tumor (T). Includes tumor thickness and ulceration, the breakdown of the skin over the melanoma.
  2. The spread to nearby lymph nodes (N).
  3. The spread (metastasis) to distant sites (M).

The table below is a simplified version of the most recent TNM system, effective as of 2018. Melanoma staging can be very complex, so if you have any questions about the stage of your cancer or what it means, ask your doctor to explain it to you in a way you understand.

AJCC Stage Melanoma Stage Description
0 The cancer is confined to the epidermis, the outermost skin layer (Tis). It has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).

This stage is also known as melanoma in situ.

I The tumor is no more than 2mm (2/25 of an inch) thick and might or might not be ulcerated (T1 or T2a). The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0)
 

II

The tumor is more than 1 mm thick (T2b or T3) and may be thicker than 4 mm (T4). It might or might not be ulcerated. The cancer has not spread to nearby lymph nodes (N0) or to distant parts of the body (M0).
IIIA The tumor is no more than 2 mm thick and might or might not be ulcerated (T1 or T2a). The cancer has spread to 1 to 3 nearby lymph nodes, but it is so small that it is only seen under the microscope (N1a or N2a). It has not spread to distant parts of the body (M0).
 

IIIB

 

There is no sign of the primary tumor (T0) AND:

The cancer has spread to only one nearby lymph node (N1b) OR

It has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the nearby lymph nodes) (N1c)

It has not spread to distant parts of the body (M0).

OR
The tumor is no more than 4 mm thick and might or might not be ulcerated (T1, T2, or T3a) AND:

The cancer has spread to only one nearby lymph node (N1a or N1b) OR

It has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (without reaching the nearby lymph nodes) (N1c) OR

It has spread to 2 or 3 nearby lymph nodes (N2a or N2b)

It has not spread to distant parts of the body (M0).

IIIC There is no sign of the primary tumor (T0) AND:

The cancer has spread to 2 or more nearby lymph nodes, at least one of which could be seen or felt (N2b or N3b) OR

It has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor, and it has reached the nearby lymph nodes (N2c or N3c) OR

It has spread to nearby lymph nodes that are clumped together (N3b or N3c)

It has not spread to distant parts of the body (M0).

OR
The tumor is no more than 4 mm thick, and might or might not be ulcerated (T1, T2, or T3a) AND:

The cancer has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor, and it has reached nearby lymph nodes (N2c or N3c) OR

The cancer has spread to 4 or more nearby lymph nodes (N3a or N3b), or it has spread to nearby lymph nodes that are clumped together (N3b or N3c)

It has not spread to distant parts of the body (M0).

OR
The tumor is more than 2 mm but no more than 4 mm thick and is ulcerated (T3b) OR it is thicker than 4 mm but is not ulcerated (T4a).

The cancer has spread to one or more nearby lymph nodes AND/OR it has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor (N1 or higher).

It has not spread to distant parts of the body.

OR
The tumor is thicker than 4 mm and is ulcerated (T4b) AND:

The cancer has spread to 1 to 3 nearby lymph nodes, which are not clumped together (N1a/b or N2a/b) OR

It has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor, and it might (N2c) or might not (N1c) have reached 1 nearby lymph node)

It has not spread to distant parts of the body (M0).

IIID The tumor is thicker than 4 mm and is ulcerated (T4b) AND:

The cancer has spread to 4 or more nearby lymph nodes (N3a or N3b) OR

It has spread to nearby lymph nodes that are clumped together (N3b)

It has spread to very small areas of nearby skin (satellite tumors) or to skin lymphatic channels around the tumor, AND it has spread to at least 2 nearby lymph nodes, or to lymph nodes that are clumped together (N3c) OR

It has not spread to distant parts of the body (M0).

IV The tumor can be any thickness and might or might not be ulcerated (any T). The cancer might or might not have spread to nearby lymph nodes (any N). It has spread to distant lymph nodes or to organs such as the lungs, liver or brain (M0).

Source: American Cancer Society