Section Editor: Allison Osmond MD FRCPC
June 18, 2026
Primary cutaneous anaplastic large cell lymphoma is a type of cancer that develops in the skin. It belongs to a group of conditions called primary cutaneous CD30-positive T-cell lymphoproliferative disorders. A lymphoma is a cancer that arises from white blood cells, and in this disease, the cancer cells come from T cells, a type of white blood cell that normally helps the immune system. The cancer cells are large and have an irregular, or anaplastic, appearance, and more than 75% of them carry a marker called CD30, which helps doctors identify the disease.
This article explains what a diagnosis of primary cutaneous anaplastic large cell lymphoma means, what the findings in your pathology report describe, and how those findings guide the decisions you and your care team make together. The word “primary” means the lymphoma starts in the skin rather than spreading there from elsewhere. This is an important distinction because primary cutaneous anaplastic large cell lymphoma usually remains limited to the skin and has an excellent prognosis.
What are the symptoms of primary cutaneous anaplastic large cell lymphoma?
This lymphoma usually presents as a single tumor in the skin, though it can less commonly involve a mucous membrane, such as the lining of the mouth. The tumor is often a firm, raised red or purple lump that can vary in size, and its surface may break open, forming an ulcer that can be uncomfortable or painful. In most cases, only one tumor is present, but about 20% of people develop more than one tumor in different areas of the skin, either at the same time or over weeks to months. In some people, skin lesions shrink or disappear on their own and then return, which is a recognized feature of this disease.
What causes primary cutaneous anaplastic large cell lymphoma?
The exact cause is not well understood. The disease develops when genetic changes occur in T cells, allowing them to grow uncontrollably and form a cancer in the skin. It is not contagious and is not inherited.
How is the diagnosis made?
The diagnosis begins with a medical history and physical examination. When a lymphoma is suspected, a small sample of the affected skin is removed in a biopsy and examined under the microscope by a pathologist. Under the microscope, the cancer cells are large, with irregularly shaped nuclei (the part of the cell that holds genetic material), prominent nucleoli (small structures inside the nucleus), and abundant cytoplasm (the material surrounding the nucleus). They usually form dense clusters or sheets in the skin and are rarely seen within blood vessels or lymphatic channels.
To confirm the diagnosis, the pathologist uses immunohistochemistry (special stains that detect proteins in the cells). The cancer cells usually show markers of activated T cells, such as CD4, and may lose other T-cell markers, including CD2, CD3, CD5, or CD7. The hallmark finding is that more than 75% of cells are CD30-positive. Some cells may also carry cytotoxic proteins such as TIA-1 or granzyme B, and occasionally other markers such as CD8 or CD56, which do not usually change the outlook.
Importantly, this is both a clinical and a pathologic diagnosis: the microscopic picture alone cannot always separate it from related conditions. The pathologist often signs the case out as a “primary cutaneous CD30-positive T-cell lymphoproliferative disorder” and lists other possibilities, including CD30-positive mycosis fungoides, lymphomatoid papulosis (a related, benign-behaving condition in the same family), and systemic anaplastic large cell lymphoma that has spread to the skin. Imaging and clinical information about how the lesions behave over time are usually needed to reach the final diagnosis and to confirm that the disease is truly limited to the skin.
Biomarker and molecular testing
Biomarkers are features of the cancer that provide information beyond the diagnosis itself, such as which treatments may help. In primary cutaneous anaplastic large cell lymphoma, two are especially relevant.
- CD30 — By definition, more than 75% of the cancer cells in this lymphoma are CD30 positive. Beyond confirming the diagnosis, strong CD30 expression means a targeted drug directed against CD30, called brentuximab vedotin, can be an effective option, particularly for widespread or recurrent disease.
- ALK — A protein produced when the ALK gene is rearranged. Primary cutaneous anaplastic large cell lymphoma is usually ALK negative. An ALK positive result raises the possibility that the lymphoma is a systemic anaplastic large cell lymphoma involving the skin rather than a primary skin lymphoma, which would change the evaluation and treatment.
You can read more in the Biomarkers section of this site.
How is primary cutaneous anaplastic large cell 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 Organization 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?
The prognosis for primary cutaneous anaplastic large cell lymphoma is generally very good. About 90% of people are alive 10 years after diagnosis, and the disease usually stays limited to the skin. Even when it spreads to nearby lymph nodes, this does not usually change the overall outlook, and skin lesions that come and go (or return after treatment) are common and do not mean the disease is worsening. The outlook may be somewhat less favorable in certain situations, including:
- Extensive skin involvement — Particularly involvement of the legs.
- Older age — Being over 60 at the time of diagnosis.
What happens after this diagnosis?
Because the disease usually remains confined to the skin and has an excellent outlook, treatment is often gentle and focused on the skin. Care is usually coordinated by a team that may include a dermatologist, a hematologist, or a medical oncologist, and a radiation 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:
- Surgery or local radiation — For a single lesion or disease limited to one area, removing the lesion and/or treating it with radiation is often very effective.
- Observation — Because some lesions shrink or disappear on their own, watchful waiting is sometimes appropriate.
- Treatment for widespread skin disease — When many lesions are present, options include low-dose methotrexate or the CD30-targeted drug brentuximab vedotin.
- Systemic therapy — Reserved for the uncommon situation where the disease spreads beyond the skin, and may include brentuximab vedotin or chemotherapy.
Regular follow-up with skin examinations is an important part of care, both to treat new lesions and to confirm the disease remains limited to the skin.
Questions to ask your doctor
- Is my lymphoma limited to the skin (primary cutaneous), and how do you know?
- Do I have one lesion or several, and what stage is my disease?
- Were my cells CD30 positive, and were any tested for ALK?
- Were any lymph nodes or other areas involved?
- Is my disease the type that may come and go on its own?
- Which treatment is best for me: surgery, radiation, observation, or medication?
- Would brentuximab vedotin be considered in my case?
- What is my outlook, and how likely is the disease to come back?
- 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:
