SUN-475 Thyroid Extranodal Diffuse Large B-Cell Lymphoma in Setting of Gastric Large B-Cell Lymphoma

Background: We report a case of concomitant thyroid and gastric diffuse large B-cell lymphoma (DLBCL). Clinical Case: A 73 year-old man presented with melena of 2 days duration. EGD revealed a 1.5 x 0.7 cm gastric ulcer. Biopsy revealed marked chronic active gastritis with glandular atypia, positive for H. pylori. Repeat biopsy of the same ulcer post H. pylori treatment demonstrated high-grade B-cell lymphoma. Immunostains were positive for CD20, CD10, BCL6, cyclin D and negative for CD 23 and CD 30. More than 95% of tumor cells expressed Ki-67, while 10% expressed MUM-1 and BCL2. Benign T cells stained positive for CD3 and CD5. FISH was negative for gene rearrangement involving BCL-6/BCL-2 and C-MYC. Staging PET/CT showed hypermetabolic regions involving the stomach wall, large left neck mass and right lung focus. The neck focus had a max SUV 48.5 (8 fold greater than the other sites), that localized to a soft tissue mass measuring 4.9 x 2.7 cm. FNA of the left-sided thyroid mass showed diffuse large B-cell lymphoma with immunostain positive for CD20 and negative for cytokeratin AE1-3, PAX8, and CD 10. The morphology was similar to that of abnormal lymphoid cells in the gastric biopsy. Patient had normal thyroid function tests but positive autoimmune thyroid disease markers (TPO and anti-TG antibody). Treatment with R-CHOP resulted in shrinkage of neck mass. Conclusion: Hypermetabolic regions revealed by PET/CT at distant sites from primary tumor require further evaluation including biopsy as indicated. Clinical correlation and response to chemotherapy can provide supplemental information in the overall assessment of the disease process.