Diagnosis guide · Lymphomas
Cutaneous T-cell lymphoma (CTCL)
If you or someone you love has just heard this diagnosis, start here. It covers several subtypes, and this guide shows how they differ, so you can find the one on your report.
Cutaneous T-cell lymphoma (CTCL) is a group of non-Hodgkin lymphomas in which T cells, a kind of white blood cell, become cancerous and affect the skin. Mycosis fungoides and Sézary syndrome are the two most common types. A sign of mycosis fungoides is a red rash on the skin. In Sézary syndrome, cancer cells are also found in the blood, and the skin over much of the body is red and itchy. Early-stage mycosis fungoides is often treated on the skin, with light therapy, radiation or medicines put on the skin. More advanced disease, including Sézary syndrome, may need medicines that work throughout the body. A transplant is generally not recommended for early-stage disease. A donor stem cell transplant is considered for selected people with advanced or hard-to-treat disease.
In short
- Cutaneous T-cell lymphoma is a group of non-Hodgkin lymphomas that affect the skin. They start when T cells, a kind of white blood cell, become cancerous.
- Mycosis fungoides and Sézary syndrome are the main types. Early mycosis fungoides is often treated on the skin with light therapy, radiation or skin medicines.
- A transplant is generally not recommended for early-stage disease. A donor stem cell transplant is considered for selected people with advanced or hard-to-treat disease.
2 subtypes
Find the subtype on your report
The exact diagnosis shapes the treatment options. Your care team can explain the name on your report.
Mycosis fungoides
Mycosis fungoides is a T-cell lymphoma that usually begins in the skin. Early disease is often treated with skin-directed therapies; a donor stem cell transplant is an option for selected advanced or difficult-to-treat cases.
Limited transplant roleSézary syndrome
Sézary syndrome is a mature T-cell lymphoma involving the blood and usually causing widespread inflamed, itchy skin. Systemic treatment is central; a donor stem cell transplant can offer lasting remission for selected eligible patients.
Donor transplant option
Nearby
Related diagnosis guides
What to know
Key facts
- New cases, U.S. SEER areas
- About 8.6 per million people a yearAge-adjusted rate, U.S. SEER areas, 2000–2018 (Cai et al., JAMA Oncology, 2022). Source: New cases, U.S. SEER areas
- Most common type
- Mycosis fungoidesPrimary cutaneous T-cell lymphomas, U.S. SEER areas, 2000–2018 (Cai et al., JAMA Oncology, 2022). Source: Most common type
- Contagious?
- No; it cannot pass from person to personCutaneous Lymphoma Foundation, accessed 2026-09-26. Source: Contagious?
- Early-stage mycosis fungoides
- Most people have a normal life expectancyEarly-stage mycosis fungoides, Cutaneous Lymphoma Foundation, accessed 2026-09-26. Source: Early-stage mycosis fungoides
- Transplant
- Not advised for early stage; donor transplant for poor-risk stage IIB–IVEuropean EBMT transplant indications, 2025. Source: Transplant
How cutaneous T-cell lymphoma is diagnosed
CTCL often starts as a scaly, red rash that can look like eczema. The rash may come and go for years, often 2 to 10, before a biopsy confirms the diagnosis. The key test is a skin biopsy, where a doctor removes a small piece of skin to study under a microscope. More than one biopsy is often needed. The Cutaneous Lymphoma Foundation stresses having the result confirmed by a pathologist who is expert in skin lymphomas (a dermatopathologist or hematopathologist).
More lab tests help show that the T cells are cancerous. Immunophenotyping and flow cytometry look at markers on the cells. A T-cell receptor gene rearrangement test checks whether large numbers of T cells share the same receptor, a sign they came from one abnormal cell (a clone). Blood tests include a complete blood count and a count of Sézary cells, the cancerous T cells found in blood. Sézary syndrome is usually defined by a T-cell clone in the blood plus at least 1,000 Sézary cells per microliter of blood.
Staging shows how far the lymphoma has spread. It looks at the skin (patches, plaques or tumors), lymph nodes, blood and internal organs. Tests may include a chest X-ray, CT or PET scans, a lymph node biopsy and, sometimes, a bone marrow sample. Stages run from IA, the earliest, to IVB. The stage helps guide treatment, from skin-directed care to medicines that work throughout the body.
When transplant specialists are usually consulted
European transplant guidance (EBMT, 2025) says transplant is generally not recommended for early-stage CTCL. For poor-risk stage IIB–IV disease, such as CTCL that comes back after first treatment, shows large-cell transformation or has spread to lymph nodes or organs, it recommends a donor transplant as soon as the disease is well controlled.
Read the guidanceLooking ahead
Outlook for cutaneous T-cell lymphoma
Outlook depends most on the type and stage. The Cutaneous Lymphoma Foundation says most people with mycosis fungoides are diagnosed at an early stage and have a normal life expectancy. For many, CTCL is a long-term condition that is treated and watched over years.
The National Cancer Institute says mycosis fungoides and Sézary syndrome are hard to cure, and treatment usually aims to ease symptoms and improve quality of life. In U.S. cancer registries, about 84 in 100 adults with mycosis fungoides were alive five years after diagnosis. That figure counts deaths from any cause, and CTCL is more common in people over 50. Sézary syndrome is less common and more serious; its own page gives its figures.
A worse outlook is linked with stage IV disease, age over 60 and a high blood level of an enzyme called LDH. It is also linked with large-cell transformation, when the cells change to a faster-growing form. For advanced stages (IIB to IV), European transplant guidance says a donor transplant can give a lasting graft-versus-lymphoma effect. This means the donor’s immune cells keep attacking the lymphoma.
About these numbers. Each one says which group of people it comes from, and the place and years where the source gives them. It describes what happened across that group, not what will happen to any one person. And a figure measured among people who had a transplant is not the same as the number of people who need one.
- 84%Mycosis fungoides: alive 5 years after diagnosis
7,957 adults diagnosed with mycosis fungoides in U.S. SEER-18 registry areas, 2000–2018; overall survival, deaths from any cause counted
Read the source: Mycosis fungoides: alive 5 years after diagnosis
This figure covers adults with mycosis fungoides at any stage, and stage was not recorded for many of them. It does not describe advanced disease or Sézary syndrome, and it cannot predict how any one person will do.
Common questions
Is cutaneous T-cell lymphoma a skin cancer?
Not exactly. CTCL is a lymphoma, a cancer of T cells, a kind of white blood cell, that shows up in the skin. The Cutaneous Lymphoma Foundation notes it is sometimes called a skin cancer because it affects the skin. But skin cancers usually start in other kinds of skin cells, not in lymphocytes. CTCL is a type of non-Hodgkin lymphoma.
What are the first signs of CTCL?
The main sign of mycosis fungoides is a red rash. It may start as flat, scaly patches, then become raised plaques and, in some people, tumors. In Sézary syndrome, the skin all over the body is red, itchy, peeling and painful. Early CTCL can look like eczema, so a skin biopsy is needed to tell them apart.
Is CTCL contagious?
No. The Cutaneous Lymphoma Foundation says CTCL is not an infection and cannot be passed from person to person.
Is cutaneous T-cell lymphoma curable?
The National Cancer Institute says mycosis fungoides and Sézary syndrome are hard to cure, and treatment usually aims to ease symptoms and improve quality of life. Some people have long remissions, and many live with CTCL for years as a long-term condition. For selected people with advanced disease, a donor stem cell transplant can give lasting control, but it carries serious risks.
What is the life expectancy with CTCL?
It depends most on the type and stage. Most people with early-stage mycosis fungoides have a normal life expectancy. Sézary syndrome and advanced mycosis fungoides have a more serious outlook. The outlook section on this page gives the figures, with the groups they describe. No number can predict how one person will do.
Is a stem cell transplant used for CTCL?
Only for some people. European transplant guidance (EBMT, 2025) says transplant is generally not recommended for early-stage CTCL, which has an excellent outcome. For poor-risk stage IIB–IV disease, it recommends a donor (allogeneic) transplant once the disease is well controlled. A transplant using a person’s own cells is generally not recommended, because relapse rates are high.
For your next appointment
Cutaneous T-cell lymphoma (CTCL)
From the Jada Bascom Foundation disease library, jadabascomfoundation.org. Printed .
Questions to bring to your care team
- Which type is it, mycosis fungoides, Sézary syndrome or another CTCL, and what stage?
- Has a pathologist who is expert in skin lymphomas reviewed the biopsy, and has my blood been checked for Sézary cells?
- What is the goal of this treatment: clearing the skin, easing itch, or longer-term control?
- If the disease is advanced or comes back, when would you want me to see a transplant center?
- Are there clinical trials that might fit?
- Where can our family find support during treatment?
A one-page list to take to the next appointment, with room for notes.
Supporting someone with a diagnosisSupport for patients and families
These independent organizations offer information and support. JBF is not affiliated with them.
- Cutaneous Lymphoma Foundation Nonprofit focused on skin lymphomas such as mycosis fungoides and Sézary syndrome, connecting patients and caregivers with education and support.United States
- Lymphoma Action UK charity for people affected by lymphoma, with a free helpline, support meetings and peer buddies; it covers cutaneous T-cell lymphoma.United Kingdom
- Lymphoma Research Foundation US nonprofit devoted to lymphoma; it explains cutaneous T-cell lymphoma and runs a helpline for patients and families.United States
Ways to help
Help another family understand.
Most people with cutaneous T-cell lymphoma (CTCL) are treated without a registry donor. A clear explanation can help the next family who hears this diagnosis, and many people with other blood cancers and blood disorders need a donor who is a stranger.
Learn and share
Most families meet these words for the first time at a diagnosis. Passing on a plain, sourced explanation is a real help.
Support this work
Gifts to the Jada Bascom Foundation support donor-awareness education like this page, community outreach, drive planning and referrals to official registries.
Join the registry
JBF points you to the official registry that serves your country. It explains who can join and what donation involves.
Keep learning
Understanding transplant
Short explainers on what a transplant is and what it means for a family.
Sources and further reading
- Mycosis Fungoides (Including Sézary Syndrome) Treatment (PDQ), Patient Version
National Cancer Institute, 2025-02-12 - Indications for haematopoietic cell transplantation and CAR-T for haematological diseases, solid tumours and immune disorders: 2025 EBMT practice recommendations
EBMT / Bone Marrow Transplantation, 2025-09-09 - Mycosis Fungoides (Including Sézary Syndrome) Treatment (PDQ), Health Professional Version
National Cancer Institute, Updated 2025-02-19; accessed 2026-09-26 - Cutaneous T-cell Lymphoma
Cutaneous Lymphoma Foundation, Accessed 2026-09-26 - Incidence Trends of Primary Cutaneous T-Cell Lymphoma in the US From 2000 to 2018: A SEER Population Data Analysis
JAMA Oncology (Cai et al.), 2022-09-01 - Overall and Cause-Specific Mortality Among Patients With Cutaneous T-Cell Lymphoma in the United States
EJHaem (Shea et al.), 2025-03-04
