Clinical usefulness of F-18 FDG PET/CT in patients with hemophagocytic lymphohistiocytosis

Objectives Hemophagocytic lymphohistiocytosis (HLH) is an unusual systemic disorder associated with infections, malignant neoplasm, drugs, autoimmune disease, and various immune deficiencies. However, clinical role of FDG-PET in HLH has not been evaluated yet. We aimed to assess the clinical use of FDG-PET in HLH.

Methods Among patients underwent FDG-PET from 2007 to 2010, twelve patients who were diagnosed with HLH were enrolled. Diagnostic accuracy for detecting malignancy in patients with HLH was calculated. PET parameters (spleen and bone marrow activities), age, presence of underlying malignancy, fever, splenomegaly and hemoglobin, neutrophil, platelet, CRP, and fibrinogen were evaluated for the prediction of survival outcome.

Results Five (41.7%) of 12 patients had malignancies (4 with lymphoma, 1 with multiple myeloma). FDG-PET could detect malignancy in 4 patients and missed in 1 (T-cell lymphoma). The sensitivity, specificity and diagnostic accuracy for detecting malignancy was 80%, 57%, and 75%, respectively. During a follow-up period of 2 months, 3 patients died. Among all parameters measured, only splenic FDG uptake (SUVmean > 2.71) was related to poor survival outcomes; log-rank test (P < 0.001).

Conclusions Our preliminary results suggest that FDG-PET is useful in detecting malignancy in patient with HLH. Moreover, splenic hypermetabolism is a strong predictor of poor survival outcome in patients with HLH