Cutaneous (Skin) Lymphoma Diagnosis and Staging

July 13, 2024

This page was reviewed under our medical and editorial policy by Alex Herrera, M.D., associate professor, division of lymphoma, Department of Hematology & Hematopoietic Cell Transplantation, City of Hope^® Cancer Center Duarte

Cutaneous lymphoma is diagnosed using a variety of tests. Once a diagnosis has been made, the care team may stage the lymphoma. This process is to determine if the cancer has spread, and if so, how much of the body is involved. Staging is used to assist in building an appropriate skin lymphoma treatment plan.

How Is Cutaneous Lymphoma Diagnosed?

A variety of tests may be used to diagnose cutaneous lymphoma. Because this cancer is on the skin, it is often caught early and diagnosed with a skin biopsy. Several tests may be done to determine the type of lymphoma and how much it has spread, if at all. These tests may include:

• Physical exam and health history
• Biopsies
• Imaging tests
• Blood tests

Physical Exam and Health History

A patient’s health history, shared with his or her doctor, helps to evaluate possible skin lymphoma risk factors, such as family history, ongoing medical conditions and symptoms that may be related. These may differ from person to person, but may include abnormal bumps and skin lesions, unexplained weight changes and/or night sweats.

A physical exam may be done to note the size, shape, color and texture of any skin areas that are in question. Most doctors will also examine the rest of the body to look for other areas that may be affected.

Skin Biopsy

A skin biopsy is a procedure in which a sample of skin is removed so it may be examined under a microscope. Some types of lymphoma may be diagnosed by the way they look under a microscope. Others may be more challenging, and the sample may be sent to a pathologist for further testing. These findings will help the doctor make a diagnosis and develop a tailored treatment plan.

Types of Biopsies

There are several types of skin biopsies. A doctor will determine which to use, based on the patient’s symptoms and individual situation.

Punch biopsy: During this procedure, the skin is numbed and a tiny tool that resembles a cookie cutter is used to obtain a skin sample.

Incisional and excisional biopsies: A sample is collected for testing by cutting through the full thickness of the skin with a surgical knife. In an incisional biopsy, part of the tumor is removed for testing. In an excisional biopsy, the entire tumor is removed.

Lymph node biopsies: These are more likely performed if a patient has enlarged lymph nodes, or the doctor is concerned that the cancer has spread into the lymphatic system. Through an incision in the skin, a small part of the tumor (incisional biopsy) or the entire lymph node is removed (excisional biopsy).

Needle biopsy: Instead of cutting away a skin sample, this method draws a small sample of tissue from the tumor or lymph node using a hollow needle. Surgery is not required, but sometimes it does not retrieve enough tissue for a definitive diagnosis.

Imaging Tests

Imaging tests are rarely performed if a patient has only a few skin lesions, but their use may be indicated when a large area of the body is affected or when lymphoma cells are found in the lymph nodes or blood. These tests use X-rays, sound waves, magnetic fields or radioactive particles to make pictures of the inside of the body. They are used to find areas that may be cancerous, to see if cancer has spread or to determine the success of treatments.

Chest X-rays: These provide a picture of the chest, and they may be done to look for enlarged lymph nodes.

Computed tomography (CT) scan: A CT scan shows much more detail than an X-ray, including details of soft tissues, such as organs. This may reveal whether organs or lymph nodes are enlarged.

CT-guided needle biopsy: A doctor uses a CT scan to guide a biopsy needle through the skin toward the suspicious area. A tissue sample is removed and sent to a laboratory for examination under a microscope or for other testing.

Magnetic resonance imaging (MRI) scans: These are similar to CT scans, but use radio waves and strong magnets instead of X-rays. MRIs show great detail in the soft tissues and organs and they may be used if a CT scan cannot be done.

Ultrasound: This simple test uses no radiation. It uses a transducer that produces sound waves to look for enlarged lymph nodes or organs such as the liver and spleen. However, this procedure does not work well for looking at the chest area, as the patient’s ribs block the sound waves.

Positron emission tomography (PET) scan: For this test, the patient is injected with a slightly radioactive sugar, which is quickly absorbed by cancer cells. A special camera then creates a picture of areas where this radioactivity has accumulated. A PET scan may help determine if an enlarged lymph node is cancerous or not. It may also be used by doctors to determine the success of cancer treatments.

Blood Tests

Blood tests check specific cell types and chemicals in the blood. While they don’t diagnose lymphoma, they may help doctors determine how advanced it is.

These tests may also be used during treatments such as chemotherapy to monitor bone marrow and organ function.

In addition to microscopic examination, blood and biopsy samples may go through one or more specialized laboratory tests, including those listed below, to diagnose and stage the cancer.

Flow cytometry and immunohistochemistry: The cells are treated with antibodies to detect certain proteins on the cell surface, which may help to classify the lymphoma.

Chromosome tests: These DNA tests may help identify the type of lymphoma, and may include cytogenetic testing, fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR).

Cutaneous Lymphoma Stages

Staging systems for skin lymphomas are broken into two different systems, depending on the type of cancer:

• Mycosis fungoides and Sézary syndrome staging
• Other skin lymphomas

The International Society for Cutaneous Lymphomas (ISCL) and the European Organization for Research and Treatment of Cancer (EORTC) developed these systems for staging skin lymphomas to have a uniform way of describing how much cancer is in the body.

Staging Cutaneous Lymphoma

Stage grouping is a way to determine the overall stage of the lymphoma, taking into account everything that is known about it. Mycosis fungoides and Sezary syndrome stages range from 1 through 4. The higher the number, the more the cancer has spread. Within each stage, letters are used to stage progression. The earlier the letter, the lower the stage.

For example, Stages 1A, 1B, and 2A are considered early stages of the disease. Stages 2B through 4B are considered advanced stages, and the cancer cells have spread throughout the body.

Stage 1A Cutaneous Lymphoma

Less than 10% of the skin has red patches or plaques, and there is no blood, lymph node or organ involvement.

Stage 1B Cutaneous Lymphoma

More than 10% of the skin has red patches or plaques, but no tumors. There is no blood, lymph node or organ involvement.

Stage 2A Cutaneous Lymphoma

The skin surface has red patches or plaques (any amount), but no tumors. Lymph nodes are enlarged, but cells do not appear to be very abnormal.

Stage 2B Cutaneous Lymphoma

One or more tumors at least 1 centimeter in size are on the skin. Lymph nodes are enlarged, but cancer has not spread to them.

Stage 3A Cutaneous Lymphoma

At least 80% of the skin is reddened and may have patches, plaques or tumors. Lymph nodes may be normal or enlarged, but the cells look normal under a microscope. Cancer has not spread to other organs, and no more than 5% of the lymphocytes in the blood are Sézary cells.

Stage 3B Cutaneous Lymphoma

At least 80% of the skin is reddened and may have patches, plaques or tumors. Lymph nodes may be normal or enlarged, but the cells look normal under a microscope. Cancer has not spread to other organs, and the number of Sézary cells in the blood is low but higher than 5%.

Stage 4A Cutaneous Lymphoma

At least 80% of the skin is reddened, and cancer is found in the blood. The cancer may have spread to the lymph nodes, but not to other internal organs.

This category is further broken down into two categories, 4A1 and 4A2, based on how abnormal the cells look and how many lymphoma cells are in the blood.

Stage 4B Cutaneous Lymphoma

At least 80% of the skin is reddened, and cancer is found in the blood. Cancer has spread to other organs, such as the liver and spleen, and may have spread to the lymph nodes.

Staging for Other Skin Lymphomas

The staging system for other skin lymphomas is relatively new. The staging is similar to that for mycosis fungoides and Sézary syndrome, but based on three factors instead of four, and counts the skin lesions and locations rather than using a percent of total body surface area:

• T (1a or b, 2a, b or c, 3a or b) defines how many skin tumors there are, how large they are and if they are next to one another or in different parts of the body. For a skin lymphoma, this is the only category that occurs at the time of diagnosis.
• N (0, 1, 2, 3) describes the extent of lymph node involvement.
• M (0, 1) is for metastasis, or the spread of lymphoma to other organs.

This staging system does not provide an overall stage number, but rather a classification, such as T_2bN₀M₀.

Staging Mycosis Fungoides and Sézary Syndrome

Mycosis fungoides and Sézary syndrome are the most common types of skin lymphomas. Nearly half of all skin lymphomas are mycosis fungoides, according to the National Comprehensive Cancer Network. Sézary syndrome is a rare type of cutaneous T cell lymphoma.

While Sézary syndrome is sometimes considered an advanced form of mycosis fungoides, it is a distinct disease. It often affects most or all of the skin and may cause swollen and enlarged lymph nodes, while mycosis fungoides usually start with patchy, scaly, red lesions on the skin. These lymphomas are staged based on four factors:

• T defines how much of the total skin surface is affected by the lymphoma tumor.
• N describes the extent of lymph node involvement.
• M is for metastasis, or spread of lymphoma to other organs.
• B is for lymphoma cells in the blood.

T categories

T categories reflect the percentage of skin that is involved or if any of the lesions have become tumors.

• T1: Skin lesions cover less than 10% of the surface. These may be small patches or flat lesions, papules (small bumps) and plaques (red, raised, scaly skin patches).
• T2: Skin lesions cover 10% or more of the skin surface.
• T3: Skin has at least one tumor, defined as a lesion growing deeper in the skin, that is at least one centimeter across. That’s a little less than one-half inch.
• T4: Lesions have grown together and cover at least 80% of the skin on the body.

N categories

N categories describe the extent of lymph node involvement.

• N0: Lymph nodes are not enlarged.
• N1: Lymph nodes are enlarged, but cells examined under a microscope look normal or nearly normal.
• N2: Lymph nodes are enlarged, and cells look abnormal under a microscope.
• N3: Lymph nodes are enlarged, and cells look very abnormal under a microscope.
• NX: Lymph nodes are enlarged, but have not been biopsied. No cells are available to view.

M categories

M categories refer to metastasis.

• M0: Lymphoma cells have not spread to other organs.
• M1: Lymphoma cells have spread to other organs in the body.

B categories

B categories determine if lymphoma cells are in the blood.

• B0: No more than 5% of lymphocytes in the blood are Sézary cells.
• B1: More than 5% of cells are Sézary lymphoma cells, but less than in B2.
• B2: A high number of Sézary lymphoma cells are in the blood.