Purpose: The significance of positron emission tomography/computed tomography (PET-CT) in identifying patients with lymphoma-associated hemophagocytic lymphohistiocytosis (LAHLH) when pathological evidence is unavailable remains uncertain.
Methods: In this retrospective study, 44 HLH patients who underwent PET-CT before clinical treatment were enrolled, and 18 of them were highly suspected as LAHLH by PET-CT. We compared the PET-CT parameters between confirmed LAHLH and non-LAHLH patients. The efficacy of initial therapies for highly suspected LAHLH patients was analyzed as well.
Results: We found that the SUVSp, SUVBM, SUVLN, SUVmax, SUVLN/Li, and SUVmax/Li in LAHLH group were significantly higher than those in non-LAHLH group (p = 0.003, p = 0.034, p = 0.003, p < 0.001, p = 0.039, and p = 0.035, respectively). HLH patients with an SUVmax value >5.5, an SUVLN value >3.3, and an SUVSp value >4.8 were more likely to be LAHLH (p < 0.001, p = 0.003, and p = 0.003, respectively). And the incidence of multiple lymphadenopathy with increased FDG uptake or the incidence of multiple bone lesions in LAHLH patients was significantly higher than those in non-LAHLH group (92.9 vs. 35.7 %, p = 0.004; 42.9 vs. 0 %, p = 0.016, respectively). Furthermore, by comparing the efficacy of initial therapies for highly suspected LAHLH patients (n = 18), we indicated that the CR rate was significantly higher in lymphoma-chemotherapy group than in immunosuppressive therapy group (90 and 25 %, respectively; p = 0.013). OS analysis revealed that highly suspected LAHLH patients treated with lymphoma-chemotherapy had better prognosis (264 days) than those treated with immunosuppressive therapy (15 days) (p < 0.0001).
Conclusions: When pathological evidence is absent, PET-CT may play an important role in identifying HLH patients underlying lymphoma. Once highly suspected as LAHLH by PET-CT, lymphoma-chemotherapies that directly treat the underling lymphoma may have a relatively favorable effect and better clinical outcomes than immunosuppressive therapy.
Keywords: Chemotherapy; Differential diagnosis; Lymphoma-associated hemophagocytic lymphohistiocytosis (LAHLH); PET–CT; Prognosis.