Cutaneous lymphomas, also known as lymphomas of the skin, are cancers of the lymphocyte (a type of white blood cell) that are primarily in the skin, but may involve the lymph nodes, blood, and other organs. All cutaneous lymphomas are non-Hodgkin’s lymphoma (NHL).
American Cancer Society estimates that there were approximately 3,500 newly diagnosed cases of cutaneous lymphoma in 2012. While cutaneous lymphomas are rare, accounting for about 5 percent of all NHL, approximately 18,000 people in the United States are estimated to have cutaneous T cell lymphoma.
Types of Cutaneous Lymphoma
Classification of cutaneous lymphomas is based on the type of lymphocyte, B cell or T cell, using a combination of microscopic examination and laboratory tests that identify proteins on the lymphoma cells. There are approximately 13 types and subtypes of this disease, which can make classification challenging.
Cutaneous B cell lymphomas
Cutaneous B cell lymphomas (CBCLs) are nearly always slow growing (indolent), with a few exceptions. Prognosis (chance of recovery) from CBCL is usually very good, although many people can experience relapse after initially responding to treatment. CBCLs rarely transform into aggressive, widespread lymphomas. CBCLs can affect any age group and affect men and women equally.
There are four types of CBCL:
- Primary cutaneous follicle-center lymphoma, the most common B cell lymphoma of the skin, tends to be found on the scalp, forehead, or torso. It is slow growing and is typically found in middle-aged adults
- Primary cutaneous marginal-zone B-cell lymphoma, also slow growing, is the second most common form of CBCL. It is commonly found on extremities and sun-exposed areas of the skin, such as the arms. Often there is only one to a few lesions. It occurs at any age and is usually curable.
- Primary cutaneous diffuse large B-cell lymphoma (leg type) is different than the others. It is a rapidly growing lymphoma that begins, as the name implies, mainly on the lower legs. It occurs most often in older people, and is more common in women than men. In this more aggressive type, the lesions may grow into large tumors that extend deep into the body, they may become open sores, and may spread to lymph nodes and internal organs. These lymphomas often require more intensive treatment.
- Primary cutaneous diffuse large B cell lymphoma (other) are rare skin lymphomas, including intravascular large B cell lymphoma, T cell rich large B cell lymphoma, plasmablastic lymphoma, and anaplastic B cell lymphoma. They develop on other (non-leg) sites in the body and can also develop inside blood vessels under the skin. They are typically manifestations of systemic lymphomas. Like the leg type, they tend to require intensive treatment.
Cutaneous T cell lymphomas
Cutaneous T cell lymphoma (CTCL) is one of the most common forms of T cell lymphoma and includes:
- Mycosis fungoides, a T cell type, the most common type of CTCL. It accounts for about 50 percent of all cutaneous lymphomas. It is a low-grade lymphoma that primarily affects the skin. Generally it is slow to progress and often remains confined to the skin. While it can occur at any age, it is mostly found in patients in their 50s and 60s and is found about twice as often in men. Mycosis fungoides is typically slow growing.
- Sezary syndrome, which affects both the skin and the peripheral blood, making it a leukemic form of CTCL. It tends to be more aggressive than mycosis fungoides. Sezary syndrome can affect people of any age, but it usually occurs in people over age 50 and is slightly more common in men.
- Cutaneous anaplastic large cell lymphoma, (ALCL) usually starts as a single tumor that is confined to the skin. It is less aggressive than systemic ALCL. Relapses, which occur frequently, are generally confined to the skin and are treated as a slow growing (indolent) lymphoma. While it can occur in children, it is generally found in people in their 50s and 60s and is found twice as often in men.
- Subcutaneous panniculitis-like T cell lymphoma is very rare. It causes nodules deep in the skin and while it is most often found in the legs, it can occur anywhere on the body. This slow growing cutaneous lymphoma affects people of all ages and both sexes equally.
- Primary cutaneous peripheral T cell lymphoma includes several types of rare cutaneous lymphomas that don’t fit into any of the other categories, including a) primary cutaneous aggressive epidermotropic CD8+ cytotoxic T-cell lymphoma, b) cutaneous gamma/delta T-cell lymphoma, and c) primary cutaneous CD4+ small/medium sized pleomorphic T-cell lymphoma. Skin lymphomas that don't fall into any of these three categories are called primary cutaneous peripheral T-cell lymphoma, unspecified.
- Lymphomatoid papulosis, or LyP, is a skin condition with features that are similar to primary cutaneous anaplastic large cell lymphoma. While LyP is classified as pre-cutaneous T cell lymphoma, it is a chronic skin condition that may come and go spontaneously, even without treatment. The American Cancer Society does not classify it as a form of cancer.