Tests and procedures used to diagnose cutaneous B-cell lymphoma include:

• Physical exam. Your healthcare professional will carefully check your skin. Your health professional looks for other signs that may give clues about your diagnosis.
• 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. A sample of your blood may be analyzed to look for lymphoma cells.
• Bone marrow biopsy. A sample of your bone marrow may be tested to look for lymphoma cells.
• Imaging tests. Imaging tests may help your healthcare professional assess your condition. Examples of imaging tests include computerized tomography scans, also called CT scans, and positron emission tomography scans, also called PET scans.