Original article False-positive F-18 FDG uptake in PET/CT studies in pediatric patients with abdominal Burkitt’s lymphoma Raef Riad a , Walid Omar a , Iman Sidhom b , Manal Zamzam b , Iman Zaky c , Magdy Hafez d and Hussein M. Abdel-Dayem e Introduction In pediatric patients with abdominal Burkitt’s lymphoma, the involvement of the gastrointestinal tract and abdominal lymph nodes are the main presenting feature of the disease. Chemotherapy is the main treatment modality and could be preceded by surgical excision of the abdominal masses. To achieve cure or long-term disease-free survival a balance has to be struck between aggressive chemotherapy and the probability of tumor necrosis secondary to treatment complicated by acute infections, perforation or intestinal bleeding. F-18 fluorodeoxyglucose-positron emission tomography/ computed tomography (F-18 FDG-PET/CT) has been recommended over conventional imaging modalities for the follow-up of these patients and for monitoring treatment response. As the incidences of postchemotherapy complications are high, the positive predictive value of PET/CT studies in these patients is very low and the false-positive rate is high from acute infections and tumor necrosis. Accordingly, histopathological confirmation of positive lesions on F-18 FDG-PET/CT studies is essential. This is especially important as post-therapy complications might present with nonspecific and nonurgent symptoms. At the same time initiating a second course of salvage chemotherapy is risky. Aim of study Retrospectively reviewed F-18 FDG-PET/CT studies for 28 pediatric patients with abdominal Burkitt’s lymphoma and diffuse large B-cell lymphoma after their treatment with chemotherapy or surgery. Results Four positive studies were found. All had pathological verification and were because of acute inflammation and tumor necrosis and there was no evidence of viable tumor cells. One patient had multiple recurrent lesions in the abdomen after the initial surgical excision and before starting chemotherapy. The incidence of acute complications in this series is 10.7%. Conclusion This study confirms the high incidence of tumor necrosis and inflammation after chemotherapy for the abdominal Burkitt’s lymphoma and consequently, the incidence of true-positive F-18 FDG studies is low. This necessitates the need for histopathological confirmation of positive studies. Nucl Med Commun 31:232–238  c 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins. Nuclear Medicine Communications 2010, 31:232–238 Keywords: abdominal Burkitt’s lymphoma, F-18 FDG-PET/CT, pediatric malignant lymphoma, tumor necrosis Departments of a Nuclear Medicine, b Pediatric Oncology, c Radiodiagnosis, d Medical Physics, Children’s Cancer Hospital, Cairo, Egypt and e Department of Radiology, Nuclear Medicine Service, St. Vincent’s Medical Centers of New York, New York, USA Correspondence to Hussein M. Abdel-Dayem, MD, FACNM, FACNP, Director, Nuclear Medicine, St. Vincent’s Medical Centers of New York, 170 West 12 Street, Cr. 327, New York, NY 10011, USA Tel: + 1 212 604 8783; fax: + 1 212 604 3119; e-mail:husseinad@aol.com Received 11 June 2009 Revised 28 August 2009 Accepted 5 November 2009 Introduction Lymphomas account for 10–15% of pediatric cancers, which represent 2–3% of all malignancies. Hodgkin’s disease represents 40% of lymphomas in children [1,2]. Non-Hodgkin’s lymphoma (NHL) represents 60% of pediatric lymphomas and occurs with a peak incidence between the ages of 5 and 9 years [3–5]. Several histological classifications exist for NHL. The revised European–American lymphoma classification is among the most widely used and focuses on the distinction between B and T-cell neoplasms [4–7]. The gastro- intestinal tract is the predominant site of extranodal NHLs [8–13]. Burkitt’s lymphoma (BL) is a rare monoclonal prolifera- tion of B-lymphocytes and is classified as a poorly differentiated lymphocytic lymphoma. It is considered the most prevalent type of lymphoma in children [13]. It is divided into African BL (endemic BL), and (sporadic BL) with the abdomen being the most common site in sporadic BL. The incidence of BL increases markedly among patients with various immunodeficiency syn- dromes, including that caused by immunosuppressive therapy, or Epstein–Barr virus infection, and human immunodeficiency virus infections [13]. Only approximately 30% of patients may be cured with en bloc resection of the involved bowel and contiguous nodes. Combination chemotherapy is the treatment of choice for patients with advanced disease [14,15]. Combination chemotherapy may improve both disease- free and overall survival compared with surgery alone 0143-3636  c 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins DOI: 10.1097/MNM.0b013e328334fc14 Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.