Types of lymphoma of the skin
Classifying lymphoma of the skin can be confusing (even for many doctors) because there are many types and they are not very common.
The main system of classification is from the World Health Organization (WHO) and the European Organization for Research and Treatment of Cancer (EORTC) and is called the WHO-EORTC classification. It classifies skin lymphomas based on 2 important pieces of information:
- How they look under the microscope
- Whether there are certain proteins on the lymphoma cells (based on lab tests)
Using this combined information, the various types of skin lymphoma can be identified.
T-cell skin lymphomas
Most skin lymphomas are T-cell lymphomas.
Mycosis fungoides: This type accounts for about half of all skin lymphomas. Mycosis fungoides (MF) can occur at any age, but most patients are in their 50s and 60s. Men are almost twice as likely as women to develop this lymphoma.
The first sign of this disease is one or more patchy, scaly, red lesions (abnormal areas) on the skin. MF lesions can be very itchy. Often these lesions are the only symptom of MF. But in some people the disease can progress to more solid, raised tumors on the skin (called plaques). Because it can be confused with other skin problems, MF may be hard to diagnose at first. Several biopsies of the lesions may be needed before the diagnosis is confirmed.
In time, the lymphoma can spread across the skin or invade lymph nodes and organs like the liver. In many patients this disease grows slowly, but it can be faster growing in older patients. Some people with MF go on to develop Sezary syndrome.
Sezary syndrome: This disease is often thought of as an advanced form of mycosis fungoides, but these are actually 2 different diseases. In Sezary syndrome (SS), most or all of the skin is involved, instead of just patches of skin. The disease causes a very itchy, red rash that can look like a sunburn. This is called generalized erythroderma. The skin is often thickened. Lymphoma cells, called Sezary cells, can be found in the bloodstream (as well as in the lymph nodes).
Patients with SS often have weakened immune systems, which increases their risk of serious infections. Whereas MF is usually slow growing, SS tends to grow and spread faster.
Primary cutaneous anaplastic large cell lymphoma (ALCL): This lymphoma usually starts as one or a few tumors on the skin. The tumors can vary in size, with some smaller than an inch across and others several inches across.
Most people with this disease are in their 50s and 60s, but it can also occur in children. It is found at least twice as often in men as in women. In most cases it does not spread beyond the skin, and the prognosis (outlook) is very good.
Lymphomatoid papulosis: This is a benign, slow-growing disease that often comes and goes on its own, even without treatment. It often begins as several large pimple-like lesions that may develop an ulcer in the middle. Under the microscope, lymphomatoid papulosis has certain features that may look like primary cutaneous ALCL.
This disorder of the skin is seen in younger people more often than the other T-cell skin lymphomas, with an average age of around 45. Men get this disease more often than women.
This disease often goes away without treatment, but it can take anywhere from a few months to many years to go away completely. Lymphomatoid papulosis doesn’t spread to internal organs and is not fatal. Rarely, some people with this skin disorder develop some other type of lymphoma that is more serious.
Subcutaneous panniculitis-like T-cell lymphoma: This rare lymphoma invades the deepest layers of the skin, where it causes nodules (lumps) to form. Most often these develop on the legs, but they can occur anywhere on the body. This lymphoma affects all ages and both sexes equally. It usually grows slowly and tends to have a good prognosis.
Primary cutaneous peripheral T-cell lymphoma, unspecified: This is a group of rare skin lymphomas that don’t fit into any special category. There are several types.
- Primary cutaneous aggressive epidermotropic CD8+ cytotoxic T-cell lymphoma develops as widespread patches, nodules and tumors. It can sometimes look like mycosis fungoides, but a biopsy will show that it is this specific tumor.
- Cutaneous gamma/delta T-cell lymphoma develops as thickened plaques or actual tumors, mainly on skin of the arms and legs, but sometimes in the intestines or lining of the nose. This is a very aggressive lymphoma that spreads quickly. In older classification systems, this was considered a subtype of subcutaneous panniculitis-like T cell lymphoma.
- Primary cutaneous CD4+ small/medium sized pleomorphic T-cell lymphoma often starts as a single area of thickening of the skin or a tumor, but later there may be multiple tumors.
- Skin lymphomas that don’t fall into any of these 3 categories are called simply primary cutaneous peripheral T-cell lymphoma, unspecified. People can have either single or multiple nodules.
B-cell skin lymphomas
Primary cutaneous marginal-zone B-cell lymphoma: This is a very slow-growing lymphoma that is usually curable. In Europe (but not in the United States), it is sometimes linked to an infection with Borrelia, the germ that causes Lyme disease.
This lymphoma can occur at any age. It causes skin lesions that are red to purplish large pimples, plaques (raised or lowered, flat lesions), or nodules (bumps) on sun-exposed areas of skin, like the arms. There may be only a single lesion, but there can sometimes be a few.
Primary cutaneous follicle-center lymphoma: This is the most common B-cell lymphoma of the skin. It tends to grow slowly. The early lesions are groups of red pimples, nodules, or plaques that form on the scalp, forehead or trunk. They are seldom found on the legs. Sometimes the pimples change into nodules.
This type is typically found in middle-aged adults. It is very sensitive to radiation therapy, and most patients have an excellent outlook.
Primary cutaneous diffuse large B-cell lymphoma, leg type: This is a fast growing lymphoma that begins as large nodules, mainly on the lower legs. It occurs most often in older people, and is more common in women than men. In some patients, this lymphoma spreads to lymph nodes and internal organs, causing serious problems.
These lymphomas often require more intensive treatment. The outlook is best if there is only one lesion at the time of diagnosis.
Primary cutaneous diffuse large B-cell lymphoma, other (non-leg): This rare skin lymphoma is similar to large B-cell lymphomas that appear on the legs, except it develops on other sites in the body. It can also develop inside blood vessels under the skin. It tends to require intensive treatment, and the outlook is best if it is limited to only the skin.
Last Medical Review: 03/14/2013
Last Revised: 02/11/2014