What is Primary Cutaneous B-Cell Lymphoma?
Lymphomas that grow outside the nodal system, also called extranodal lymphomas, are tumors that occur in organs or tissues outside the lymphatic system. When extranodal lymphomas originate in the skin and there is no evidence of systemic or extracutaneous disease, they are called primary cutaneous lymphomas and primary cutaneous B-cell lymphomas (CBCLs) when B-cells are involved. Skin is the second most common site of extranodal involvement after the gastrointestinal tract, making up 18 percent of all extranodal lymphomas, and 5 percent of all non-Hodgkin lymphomas. The majority of primary cutaneous lymphomas are of the T-cell type, with CBCL comprising 20 percent to 25 percent of all primary cutaneous lymphomas.
Who Gets CBCL?
The disease affects men and women equally and can affect any age group. Like all lymphomas, CBCL is an acquired disease and there are no known risk factors. The disease is not inherited or contagious.
The Different Types of CBCL
Recently, the World Health Organization and European Organization for Research and Treatment of Cancer Classification reached a consensus on a classification system for CBCL and determined that there are three main types of primary cutaneous B-cell lymphomas:
Prognosis is usually very good, although relapse is common, with nearly 50 percent of CBCL patients experiencing recurrence after an initial complete response to treatment.
Brief descriptions of the main types of CBCL appear below:
Primary cutaneous follicle center lymphoma (CFCL) is the most common B-cell lymphoma to develop as a primary tumor of the skin. These skin lymphomas develop slowly over months or years and may manifest as a single tumor or nodule or be grouped together and have a pink or reddish appearance that is slightly raised and smooth and usually do not ulcerate. Cutaneous follicle center lymphoma usually appears on the head, neck or trunk of the body.
Primary cutaneous marginal zone B-cell lymphoma (CMZL) is a low-grade malignant B-cell lymphoma that is similar to the MALT (mucosa-associated lymphoid tissue) type and is the second most common form of CBCL. This slow-growing B-cell lymphoma appears as pink or red papules, nodules and/or tumors. Although CMZL can occur anywhere on the body, they are commonly found on the extremities, especially the arms and trunk.
Primary cutaneous diffuse large B-cell lymphoma
Primary cutaneous diffuse large B-cell lymphoma, leg type (LBCL-L) is less common than other types of CBCL and more aggressive, usually appearing on the lower legs of elderly women, although lesions can occur on any part of the body. The lesions are red or bluish-red and frequently grow into large tumors that extend deep into the fat. Unlike cutaneous follicle center lymphoma, LBCL-L tumors develop quickly over weeks and months, usually becoming open sores and spreading outside the skin.
Primary cutaneous diffuse LBCL-other describes a group of very rare diffuse LB- CLs that do not fit into the other LBCL categories. They include intravascular LBCL, T-cell-rich LBCL, plasmablastic lymphoma and anaplastic B-cell lymphoma. Although these lymphomas usually appear on the head, trunk or extremities, they are often cutaneous manifestations of systemic lymphomas and have to be treated the same way.
How CBCL Is Diagnosed and Staged
A biopsy of the tumor tissue is needed to render a diagnosis and determine CBCL classification. Once a diagnosis is made, CBCL patients are either referred to an oncologist or a dermatologist specializing in CBCL for clinical staging to eliminate the possibility that the disease originated outside the skin. A comprehensive CBCL staging evaluation includes:
Primary cutaneous follicle center lymphoma and cutaneous marginal zone lymphoma are among the most slow growing or indolent lymphomas and, depending on the number of lesions present, may be treated locally with either radiation or surgery. Topical steroid cream or topical chemotherapy may also be used. Sometimes no treatment is needed. Most often these slow-growing lymphomas recur over time, usually only on the skin. As many as 50 percent of people with single lesions that get radiation or excision will never get another lesion. Indolent CBCLs rarely transform into more aggressive types of lymphoma. For diseases that do transform, become widespread or in rare cases when they become systemic, a variety of chemotherapy regimens may be used. Other therapies such as the monoclonal antibody Rituxan (rituximab), either alone or in combination with chemotherapy, and interferon may also be recommended.
There is no known best treatment strategy for the more aggressive type of CBCL, primary cutaneous diffuse large-B cell lymphoma-leg type. For single tumors, radiation is often effective as are combinations of chemotherapy or radiation and chemotherapy given sequentially. All of these treatments usually put the disease in remission, although relapse is common. Research is underway to test the most effective strategies for treating cutaneous B-cell lymphomas.
Expert review by:
Steven M. Horwitz, M.D., Assistant Attending, Lymphoma Service, Memorial Sloan-Kettering Cancer Center, New York City, New York