Low Rate of Splenic Involvement in Sporadic Burkitt Lymphoma on PET CT

Objectives: Burkitt lymphoma (BL) is a highly aggressive B-cell non-Hodgkin lymphoma. Cross-sectional anatomic imaging techniques e.g., CT, US, MRI to detect spleen involvement by lymphoma have known limitations, reducing the accuracy of disease staging. This study evaluated the impact of functional imaging with PET-CT in determining splenic involvement at staging in adult patients with sporadic BL

Methods: Twenty patients with sporadic BL, (17 males, 3 women ) median age 49 years [range 22-78] underwent ¹⁸F-FDG PET-CT scans at diagnosis at Sheba Medical Center during 1/2005 - 12/2014.. Location and intensity of FDG uptake in tissues involved with BL were assessed and findings were correlated to CT scans. Splenic volume of each patient was calculated by CT (splenomegaly determined if splenic index exceeded 725 cm³). .

Results: Tissue involvement by BL was characterized by high intensity uptake of FDG with a mean SUV max of 11.4 ± 7.49 (range 4.3-38). According to PET-CT, the frequency of BL involvement in various tissues were as follows: lymph nodes n-13 (65%), intestine n- 8 (40%), intraperitoneal fat and omentum n- 7 (35%), stomach n- 5 (25 %), pleura n- 4 (20%), pancreas n-4 (20%), bone marrow n-3 (15%), adrenal gland n- 1 (5 %), liver n- 1(5 %), and seminal vesicle n- 1 (5%). The mean spleen volume (cm³) was 416.6 ± 275.7 (range 140-1358). None of the 20 patients had either focal or diffuse increased uptake of FDG in the spleen parenchyma. In 2 cases there were highly FDG avid soft tissue masses adjacent to the spleen, both in the context of direct peritoneal disease extension.

Conclusion: PET-CT revealed that highly intense FDG uptake is the hallmark of BL involvement in tissue. The spleen is rarely involved by BL and mostly related to direct extension from adjacent peritoneal mass. We conclude that PET- CT can be used for accurate assessment of staging BL, and in the event of an increased avidity of ¹⁸F-FDG in the spleen parenchyma one might reconsider diagnosis of BL. Larger scale clinical studies incorporating PET-CT scans are still needed to confirm our observation. Research Support: none