Study of Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) for the Evaluation of the Autoimmune Lymphoproliferative Syndrome (ALPS) and ALPS-Associated Lymphoma

Detailed Summary

This study will evaluate the usefulness of FDG-PET scanning in distinguishing autoimmune lymphoproliferative syndrome (ALPS) from lymphoma. Lymphoma is cancer of the lymph system. ALPS is a condition involving persistent enlargement of the lymph glands, spleen, or liver, and a range of other problems relating to blood cell counts and abnormal immune activity, in which the immune system attacks healthy tissues. People with ALPS particularly those with an abnormal Fas gene also have an increased risk of developing lymphoma. The Fas gene codes for a protein that causes immune cells called lymphocytes to die when they are no longer needed. FDG-PET is a new nuclear imaging test that is very effective in detecting lymphoma. It is important to identify these cancers as quickly as possible, since some are very curable when caught early. Since ALPS and lymphoma share several common characteristics, a reliable, non-invasive method of distinguishing the two, such as FDG-PET might offer, is crucial. FDG-PET uses a radioactive sugar molecule to produce images that show the metabolic activity of tissues. Because cancer cells grow and divide more rapidly than normal cells, they metabolize more sugar for fuel. This increased activity identifies them as cancer in FDG-PET scanning. For this procedure, the subject is injected with the sugar molecule and lies in a doughnut-shaped machine (PET camera) for the imaging. Adults and children 10 years old or older with ALPS, with or without lymphoma, may be eligible for this study. Candidates will be screened with a physical examination, blood tests, and computed tomography (CT) scan. Participants will have an FDG-PET scan and a DEXA scan. The DEXA scan measures fat and non-fat tissue and is used help interpret the FDG-PET results. For this test, the subject lies on a table while a fast X-ray is taken from head to toe. Patients who develop signs or symptoms suggesting the development or recurrence of lymphoma (such as further enlargement of lymph glands, unexplained fever or weight loss, or abnormal scans) may undergo a tissue biopsy. For this procedure, a small piece of lymph or other tissue is surgically removed for examination under the microscope. In addition, patients who develop these symptoms may be asked to undergo additional FDG-PET scans up to two a year in patients without lymphoma, and as many as needed in patients with lymphoma to evaluate their response to treatment and guide future therapy.

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