To evaluate the role of FDG-PET/CT in detecting bone marrow (BM) involvement, pre-treatment bilateral bone marrow biopsies (BMBs) and FDG-PET/CT scans of 89 patients with diffuse large B-cell lymphoma (DLBCL) treated with rituximab-CHOP were reviewed and analyzed. Fourteen patients (15.7%) had lymphomatous involvement based on BMB (BMB+), and 17 patients (19.1%) had the possibility of BM involvement on FDG-PET/CT (FDG-PET/CT+). Seventy-two patients (80.8%) had concordant results between BMB and FDG-PET/CT (seven patients were positive for both, and 65 patients were negative for both), but 17 patients (19.2%) had a discordant interpretation (seven patients were BMB+ and FDG-PET/CT-, and ten were BMB- and FDG-PET/CT+). Although BMB+ patients had an inferior 2-year EFS (37.0% vs. 79.8%, p < 0.001) and OS (36.3% vs. 81.0%, p < 0.001) compared to BMB- patients, no differences in EFS (62.6% vs. 72.7%, p = 0.185) and OS (59.4% vs. 78.0%, p = 0.146) were shown between FDG-PET/CT+ and FDG-PET/CT- patients. Whereas six of seven patients with diffuse hypermetabolism were BMB+, only one of ten patients with focal hypermetabolism was BMB+. The results suggest that FDG-PET/CT had a limited value to detect BM involvement in patients with DLBCL. Focal hypermetabolism of hematopoietic BM in FDG-PET/CT had no impact on survival.

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B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL) (intermediate DLBCL/BL), is a heterogeneous group with some features resembling DLBCL and others resembling BL. Here, we report a case of intermediate DLBCL/BL in a Korean child. A 2-yr-old male was admitted for evaluation and management of left hip pain. Immunohistochemistry of a biopsy of the femur neck revealed tumor cells positive for CD20, CD10, BCL2, BCL6, and Ki67. A bone marrow (BM) aspirate smear revealed that 49.3% of all nucleated cells were abnormal lymphoid cells, composed of large- and medium-sized cells. Immunophenotyping of the neoplastic cells revealed positivity for CD19, CD10, CD20, and sIg lambda and negativity for CD34, Tdt, and myeloperoxidase (MPO). Cytogenetic and FISH analyses showed a complex karyotype, including t(8;14)(q24.1;q32) and IGH-MYC fusion. Intensive chemotherapy was initiated, including prednisone, vincristine, L-asparaginase, daunorubicin, and central nervous system prophylaxis with intrathecal methotrexate (MTX) and cytarabine. One month after the initial diagnosis, BM examination revealed the persistent of abnormal lymphoid cells; cerebrospinal fluid cytology, including cytospin, showed atypical lymphoid cells. The patient was treated again with cyclophosphamide, vincristine, prednisone, adriamycin, MTX, and intrathecal MTX and cytarabine. The patient died of sepsis 5 months after the second round of chemotherapy.

Radioiodine is regularly used in the treatment of thyroid cancer to eliminate residual malignant tissue after thyroidectomy and to treat metastasis. Because of the low dose of radioiodine used to treat thyroid cancer patients, leukemia is an uncommon complication of exposure to radioiodine. Here, we present a patient who developed therapy-related acute myeloid leukemia with inv(16)(p13.1q22);CBFβ-MYH11, eosinophilia, and K-ras mutation and who had been treated with very low-dose radioiodine following total thyroidectomy.

5204 Backgrounds: As a bone marrow bopsy (BMB) is a painful and invasive procedure with a restrictive reliability as only a limited area of the bone marrow (BM) can be evaluated, role of FDG-PET/CT to demonstrate lymphomatous BM involvement as an alternative or at least a complementary to BMB is an area of interest. Several previous studies exist but most of them included heterogeneous types of lymphomas with various treatments. Patients and methods: To evaluate the role of FDG-PET/CT in detecting BM involvement, pre-treatment bilateral BMBs and FDG-PET/CT scans of 89 patients with diffuse large B-cell lymphoma (DLBCL) treated with standard immunochemotherapy, rituximab-CHOP were reviewed and analyzed. Uptake more than liver parenchyma intensity on FDG-PET/CT was interpreted as 'with a possibility' of involvement. The final interpretation on the possibility of BM involvement in each patient was reported after discussion among three nuclear medicine physicians and results of BMB were blinded at the time of FDG-PET/CT review. Fourteen patients (15.7%) had lymphomatous involvement based on BMB (BMB+) and 17 patients (19.1%) had the possibility of BM involvement on FDG-PET/CT (FDG-PET/CT+). Seventy-two patients (80.8%) had concordant results between BMB and FDG-PET/CT (7 patients were positive for both and 65 patients were negative for both), but 17 patients (19.2%) had a discordant interpretation (7 patients were BMB+ and FDG-PET/CT-, and 10 for BMB- and FDG-PET/CT+; table 1). Although BMB+ patients had an inferior 2-year EFS (37.0% vs. 79.8%, p < 0.001) and OS (36.3% vs. 81.0%, p < 0.001) compared to BMB- patients, no differences in EFS (62.6% vs. 72.7%, p = 0.185) and OS (59.4% vs. 78.0%, p = 0.146) were shown between FDG-PET/CT+ and FDG-PET/CT- patients. Six of 7 patients with BMB+ and FDG-PET/CT+ had a diffuse involvement on FDG-PET/CT whereas 9 of 10 patients with BMB- and FDG-PET/CT+ had a focal BM involvement on FDG-PET/CT (table 2). Six of 7 patients with diffuse involvement on FDG-PET/CT were BMB+ whereas only 1 of 10 patients with focal BM involvement on FDG-PET/CT were BMB+ (table 2). It is likely therefore that patients with diffuse BM involvement on FDG-PET/CT had higher probability for BMB+ and they might have poorer survival than those with focal BM involvement. Conclusion: The results suggest that FDG-PET/CT had a limited value to detect BM involvement in patients with DLBCL. It may not be justified to upgrade patient's Ann Arbor stage to IV according to focal hypermetabolic BM lesion on FDG-PET/CT. Until additional results on the role of FDG-PET/CT in detecting BM involvement available, FDG-PET/CT should be used as an adjuvant rather than an alternative in detecting BM involvement in patients with newly diagnosed DLBCL. Disclosures: No relevant conflicts of interest to declare.