Section Editor: Allison Osmond MD FRCPC
June 18, 2026
Primary cutaneous follicle centre lymphoma is a type of cancer called a lymphoma that starts in the skin. It develops from B cells, a type of white blood cell that normally helps the immune system fight infection. The word “primary” means the lymphoma begins in the skin rather than spreading there from elsewhere, and at the time of diagnosis, it is confined to the skin rather than involving lymph nodes or internal organs.
This article explains what a diagnosis of primary cutaneous follicle centre lymphoma means, what the findings in your pathology report describe, and how those findings guide the decisions you and your care team make together. This is one of the most treatable forms of lymphoma: it usually grows slowly, tends to stay in the skin, and has an excellent outlook.
What are the symptoms of primary cutaneous follicle centre lymphoma?
Primary cutaneous follicle centre lymphoma usually appears as one or more painless lumps or raised patches (plaques) on the head, neck, or upper body, although it can appear elsewhere on the skin. The lesions are typically red or pink and slow-growing, and they usually do not itch or cause discomfort. Because they can look like other skin conditions, the disease may go unnoticed at first. Over time the lumps may grow thicker, but they usually remain painless and limited to one area.
What causes primary cutaneous follicle centre lymphoma?
The exact cause is not known. The disease develops when genetic changes occur in B cells in the skin, allowing them to grow uncontrollably. It is not contagious and is not inherited. Environmental and immune-related factors may contribute, but no specific cause has been identified.
How is the diagnosis made?
The diagnosis is made after a sample of affected skin is removed in a biopsy and examined under the microscope by a pathologist. Under the microscope, the abnormal B cells are seen in the dermis (the layer beneath the skin’s surface) and sometimes extend into the underlying fat. They may grow in a follicular pattern, forming rounded clusters that resemble the follicle centres normally found in lymph nodes but lack their orderly structure, or in a diffuse pattern, spreading evenly through the skin. The cells include centrocytes (medium to large cells with irregular or folded nuclei, sometimes spindle-shaped) and larger cells called centroblasts. Normal T cells and scar-like tissue (fibrosis) are often mixed in, which can make the diagnosis more difficult.
To confirm the diagnosis and distinguish this lymphoma from other conditions, the pathologist uses immunohistochemistry (special stains that detect proteins in cells). The cells carry B-cell markers such as CD20 and CD79a, and they are positive for BCL6, which shows they come from the follicle centre. CD10 is often positive in the follicular pattern and negative in the diffuse pattern. Two findings are especially useful: the cells are usually negative (or only weakly positive) for a protein called BCL2, which helps separate this lymphoma from a follicular lymphoma that started in the lymph nodes and spread to the skin, and they are usually negative for MUM1 and FOXP1, which helps separate it from a more serious skin lymphoma called diffuse large B-cell lymphoma, leg type. Markers such as CD5 and CD43 are negative, and a marker called Ki-67, which shows how quickly the cells are dividing, may be higher in cases with a diffuse pattern. Imaging and blood tests are usually done to confirm that the disease is limited to the skin.
How is primary cutaneous follicle centre lymphoma staged?
Staging describes how much of the skin is involved and whether the disease has spread to lymph nodes or beyond. For cutaneous lymphomas other than mycosis fungoides, doctors use a TNM system developed by the International Society of Cutaneous Lymphomas (ISCL) and the European Organisation for Research and Treatment of Cancer (EORTC) that describes the skin (T), lymph nodes (N), and other organs (M).
Skin (T)
- T1 — A single lesion (T1a: smaller than 5 cm; T1b: larger than 5 cm).
- T2 — Several lesions limited to one area or two nearby areas of the body (T2a: within a 15 cm circle; T2b: within a 15 to 30 cm circle; T2c: within a circle larger than 30 cm).
- T3 — Widespread lesions (T3a: two separate body regions; T3b: three or more body regions).
Lymph nodes (N)
- N0 — No lymph node involvement.
- N1 — One lymph node group that drains an affected area of skin is involved.
- N2 — Two or more lymph node groups are involved, or nodes that do not drain the affected skin.
- N3 — Involvement of central lymph nodes deep within the body.
Other organs (M)
- M0 — No spread beyond the skin and lymph nodes.
- M1 — Spread to other organs.
What is the prognosis?
Primary cutaneous follicle centre lymphoma has an excellent prognosis. More than 95% of people are alive at least 5 years after diagnosis, and although the cells may appear abnormal under the microscope, the disease usually grows slowly and remains confined to the skin. About 30% of people develop new skin lesions (relapses) over time, but these usually do not mean the disease is becoming more serious. Lymphoma that develops on the leg may have a slightly less favorable outlook, but still responds well to treatment. Regular follow-up is important for monitoring new lesions.
What happens after this diagnosis?
Because the disease usually remains confined to the skin and has an excellent outlook, treatment is often focused on the skin. Care is usually coordinated by a team that may include a dermatologist, a radiation oncologist, and a hematologist or medical oncologist. The findings in the report, the number and location of lesions, and whether the disease has spread guide what is considered, which may include:
- Local radiation therapy — Highly effective and often the preferred treatment for one or a few lesions, frequently leading to long-lasting remission.
- Surgery — A single lesion can sometimes be removed surgically.
- Observation — Because the disease is slow-growing, watchful waiting is sometimes appropriate.
- Medication for widespread disease — When many lesions are present, a drug called rituximab, which targets the CD20 protein on B cells, may be used. Chemotherapy is reserved for the uncommon situation where the disease becomes widespread or spreads beyond the skin.
Relapses in the skin are common and are usually treated again with skin-directed therapy without changing the overall outlook. Ongoing follow-up with skin examinations is an important part of care.
Questions to ask your doctor
- Is my lymphoma limited to the skin, and how do you know?
- Do I have one lesion or several, and what stage is my disease?
- Did my lymphoma show a follicular or diffuse pattern under the microscope?
- Were the tests done to rule out a lymphoma that started in the lymph nodes or the leg-type skin lymphoma?
- Which treatment is best for me: radiation, surgery, observation, or medication?
- Would rituximab be considered in my case?
- What is my outlook, and how likely is the disease to come back?
- If it comes back, what would happen next?
- How often will I need follow-up and skin checks?
- What signs should prompt me to call you?
- Should I be seen at a center that specializes in cutaneous lymphoma?
Related articles
We are proud to partner with:
