Lymphoma of the Skin Stages

After someone is diagnosed with skin lymphoma, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Knowing the stage of a skin lymphoma may help in deciding the best treatment.

The tests used to gather information for staging include:

  • Physical exam
  • Biopsies
  • Imaging tests, such as CT scans
  • Blood tests

These tests are described in Tests for Lymphoma of the Skin.

The staging systems for skin lymphomas were developed by the International Society for Cutaneous Lymphomas (ISCL) and the European Organization for Research and Treatment of Cancer (EORTC). There are 2 different staging systems:

  • One for mycosis fungoides and Sezary syndrome
  • One for other skin lymphomas

These systems can be hard to understand. If you have questions about the stage of your lymphoma, ask your cancer care team to explain it to you in a way you understand. This can help you make choices about your treatment.

Staging for mycosis fungoides and Sezary syndrome

Mycosis fungoides (MF) and Sezary syndrome (SS) are staged based on 4 factors:

  • T describes how much of the skin is affected by the lymphoma (tumor).
  • N describes the extent of the lymphoma in the lymph nodes (bean-sized collections of immune cells).
  • M is for the spread (metastasis) of the lymphoma to other organs.
  • B is for lymphoma cells in the blood.

T categories

T1: Skin lesions can be small patches (flat lesions), papules (small bumps), and/or plaques (raised or lowered, flat lesions), but the lesions cover less than 10% of the skin surface.

T2: The patches, papules, and/or plaques cover 10% or more of the skin surface.

T3: At least one of the skin lesions is a tumor (a lesion growing deeper into the skin) that is at least 1 centimeter (cm) (a little less than 1/2 inch) across.

T4: The skin lesions have grown together to cover at least 80% of the skin surface.

N categories

N0: Lymph nodes are not enlarged and a lymph node biopsy is not needed.

N1: Lymph nodes are enlarged, but the patterns of cells look normal or close to normal under the microscope.

N2: Lymph nodes are enlarged, and the patterns of cells look more abnormal under the microscope.

N3: Lymph nodes are enlarged, and the patterns of cells look very abnormal under the microscope.

NX: Lymph nodes are enlarged but haven’t been removed (biopsied) to be looked at under the microscope.

M categories

M0: The lymphoma cells have not spread to other organs.

M1: Lymphoma cells have spread to other organs, such as the liver or spleen.

B categories

B0: No more than 5% of lymphocytes in the blood are Sezary (lymphoma) cells.

B1: Low numbers of Sezary cells in the blood (more than in B0 but less than in B2).

B2: High number of Sezary cells in the blood.

Stage grouping

Once the values for T, N, M, and B are known, they are combined to determine the overall stage of the lymphoma. This process is called stage grouping.

Mycosis fungoides (MF) and Sezary syndrome (SS) stages range from I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter means a lower stage. Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way.

Stage IA: T1, N0, M0, B0 or B1

There are skin lesions but no tumors. Skin lesions cover less than 10% of the skin surface (T1), the lymph nodes are not enlarged (N0), lymphoma cells have not spread to other organs (M0), and the number of Sezary cells in the blood is not high (B0 or B1).

Stage IB: T2, N0, M0, B0 or B1

There are skin lesions but no tumors. Skin lesions cover at least 10% of the skin surface (T2), the lymph nodes are not enlarged (N0), lymphoma cells have not spread to other organs (M0), and the number of Sezary cells in the blood is not high (B0 or B1).

Stage IIA: T1 or T2, N1 or N2, M0, B0 or B1

There are skin lesions but no tumors. Skin lesions can cover up to 80% of the skin surface (T1 or T2). Lymph nodes are enlarged but the patterns of cells do not look very abnormal under the microscope (N1 or N2). Lymphoma cells have not spread to other organs (M0), and the number of Sezary cells in the blood is not high (B0 or B1).

Stage IIB: T3, N0 to N2, M0, B0 or B1

At least one of the skin lesions is a tumor that is 1 cm across or larger (T3). The lymph nodes are either normal (N0) or are enlarged but the patterns of cells do not look very abnormal under the microscope (N1 or N2). Lymphoma cells have not spread to other organs (M0), and the number of Sezary cells in the blood is not high (B0 or B1).

Stage IIIA: T4, N0 to N2, M0, B0

Skin lesions cover at least 80% of the skin surface (T4). The lymph nodes are either normal (N0) or are enlarged but the patterns of cells do not look very abnormal under the microscope (N1 or N2). Lymphoma cells have not spread to other organs or tissues (M0), and no more than 5% of the lymphocytes in the blood are Sezary cells (B0).

Stage IIIB: T4, N0 to N2, M0, B1

Skin lesions cover at least 80% of the skin surface (T4). The lymph nodes are either normal (N0) or are enlarged but the patterns of cells do not look very abnormal under the microscope (N1 or N2). Lymphoma cells have not spread to other organs (M0), and the number of Sezary cells in the blood is low (B1).

Stage IVA1: Any T, N0 to N2, M0, B2

Skin lesions can cover any amount of the skin surface (any T). The lymph nodes are either normal (N0) or are enlarged but the patterns of cells do not look very abnormal under the microscope (N1 or N2). Lymphoma cells have not spread to other organs (M0), and the number of Sezary cells in the blood is high (B2).

Stage IVA2: Any T, N3, M0, any B

Skin lesions can cover any amount of the skin surface (any T). Some lymph nodes are enlarged and the patterns of cells look very abnormal under the microscope (N3). Lymphoma cells have not spread to other organs (M0). Sezary cells may or may not be in the blood (any B).

Stage IVB: Any T, any N, M1, any B

Skin lesions can cover any amount of the skin surface (any T). The lymph nodes may be normal or abnormal (any N), and Sezary cells may or may not be in the blood (any B). Lymphoma cells have spread to other organs, such as the liver or spleen (M1).

Staging for other skin lymphomas

The staging system for types of skin lymphoma other than mycosis fungoides and Sezary syndrome is still fairly new, and doctors are still trying to determine how useful it is. The system is based on 3 factors:

  • T describes how much of the skin is affected by the lymphoma (tumor).
  • N describes the extent of the lymphoma in the lymph nodes (bean-sized collections of immune cells).
  • M is for the spread (metastasis) of the lymphoma to other organs.

For these lymphomas, only the T category is used at the time of diagnosis. If parts of the body other than the skin (such as lymph nodes) are involved at the time of diagnosis, the lymphoma is not considered to be a skin lymphoma and is staged like regular non-Hodgkin lymphoma. The N and M categories are only used if the lymphoma progresses (continues to grow) during treatment or comes back after treatment.

T categories

T1: There is only a single skin lesion.

  • T1a: The skin lesion is less than 5 cm (about 2 inches) across.
  • T1b: The skin lesion is at least 5 cm across.

T2: There are 2 or more lesions on the skin. These may be in a single body region or in 2 body regions that are next to each other.

  • T2a: All of the skin lesions could be placed within a circle that is 15 cm (about 6 inches) across.
  • T2b: The circle needed to surround all of the skin lesions is larger than 15 cm across, but smaller than 30 cm (about 1 foot) across.
  • T2c: The circle needed to surround all of the skin lesions is larger than 30 cm across.

T3: There are skin lesions in body regions that aren’t next to each other, or in at least 3 different body regions.

  • T3a: There are skin lesions involving 2 body regions that aren’t next to each other.
  • T3b: There are skin lesions involving 3 or more body regions.

N categories

N0: No lymph nodes are enlarged or contain lymphoma cells.

N1: There are lymphoma cells in the lymph nodes that drain an area where skin contained lymphoma.

N2: One of the following is true:

  • At least 2 sets of lymph nodes from different areas contain lymphoma cells
  • There are lymphoma cells in lymph nodes that do not drain areas where the skin contained lymphoma.

N3: Lymph nodes deep inside the chest or abdomen contain lymphoma cells.

M categories

M0: No signs of lymphoma outside of the skin or lymph nodes.

M1: Lymphoma has spread to other organs or tissues.

This system does not assign an overall stage to the lymphoma, like the system for mycosis fungoides/Sezary syndrome does. Because this system is still fairly new, it’s not yet clear how well it can help predict a person’s prognosis (outlook).

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master's-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

American Joint Committee on Cancer. Primary Cutaneous Lymphomas. In: AJCC Cancer Staging Manual. 8th ed. New York, NY: Springer; 2017: 967-972.

Last Medical Review: March 29, 2018 Last Revised: March 29, 2018

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