Diagnosis of cutaneous B-cell lymphoma often begins with a physical exam. During the exam, a healthcare professional checks the skin for nodules, lesions or patches. The healthcare professional also may check for swollen lymph nodes in the neck, underarms and groin and check for an enlarged spleen or liver. Other tests and procedures include blood tests, imaging tests and taking a sample of tissue for lab testing. Cutaneous B-cell lymphoma can closely mimic systemic lymphoma. Because of this, thorough testing is needed to confirm that the cancer is limited to the skin.

Skin biopsy

A biopsy is a procedure to remove a sample of tissue for testing in a lab. Your healthcare professional may remove a small piece of the affected skin. The sample is tested in a lab to look for lymphoma cells.

Blood tests

Blood tests can sometimes show whether lymphoma cells are present. Blood tests may be used to test for viruses, including HIV, hepatitis B virus and hepatitis C virus. The presence of a virus may affect treatment options. Blood tests also measure levels of lactate dehydrogenase (LDH), which is often higher in people with systemic lymphoma.

Bone marrow biopsy and aspiration

Bone marrow biopsy and aspiration are procedures that involve collecting cells from the bone marrow. The cells are sent for testing.

In a bone marrow aspiration, a needle is used to draw a sample of the fluid. In a bone marrow biopsy, a needle is used to collect a small amount of the solid tissue. The samples most often come from the hip bone. Your bone marrow may be tested to look for lymphoma cells.

Imaging tests

Imaging tests make pictures of the body. They can show if the lymphoma is only in the skin. Tests might include CT and positron emission tomography (PET) scans.

Testing lymphoma cells in the lab

Lymphoma cells collected from a biopsy or a bone marrow aspiration and biopsy go to a lab for testing. In the lab, specialized tests look for specific things about the cells. The healthcare team uses the results to determine the type of lymphoma that you have.

To decide whether the cells are cutaneous B-cell lymphoma cells, the healthcare professionals in the lab look for:

• Proteins on the surface of the cancer cells. Cutaneous B-cell lymphoma cells have certain proteins on their surfaces that help identify them. These proteins are known as markers. These markers can help identify the type of cutaneous B-cell lymphoma.
• Changes in the cancer cell DNA. Cancer happens when cells have changes in their DNA. Lab tests can show which DNA changes are present in the lymphoma cells.