The Study On The Features Of Clinic And Imaging Of Primary Central Nervous System Diffuse Large B-cell Lymphoma And Its Correlation With Prognosis

Objective:To investigate the clinical and imaging characteristics of primary central nervous system diffuse large B-cell lymphoma（PCNS-DLBCL）in different groups,and summarize and analyze its correlation with prognosis.Methods:The clinical and preoperative multimodality imaging data from 71 patients with PCNS-DLBCL proven based on pathology were retrospectively analyzed.71 patients were divided into single,multiple and diffuse lesion groups according to the shape and number of imaging lesions.The clinical and imaging characteristics of the three groups of patients and the differences in clinical and imaging characteristics between the different groups were statistically analyzed,and the positive rates of PCNSL separately and combined diagnosis of different imaging examinations were compared.The imaging and clinical prognostic factors were screened according to the International Prognostic Index of lymphoma and previous studies,the effects of different imaging characteristics,clinical factors and treatment methods on the prognosis of PCNS-DLBCL patients were statistically analyzed.The Kaplan-Meier method was used to perform prognostic analysis based on the follow-up overall survival time,the Log-rank method was used to test the impact of single factor on survival time,and the Cox proportional hazard model was used for multivariate prognostic analysis.The poor prognostic factors of the three groups of cases were statistically analyzed and the effects of different prognostic factors on the median survival of patients were compared.Results:（1）General information:Among the 71 patients in this study,34 were male patients and 37 patients were female patients.They age varied from 18 to 82 years,with an average age of（52.83±15.38）years old.The common presenting symptoms were subacutely progressing intracranial pressure increase,focal neurological deficits symptoms and cognitive/behavioral changes.There was no statistically significant difference in age,gender and clinical symptoms among single,multiple and diffuse lesion groups.（2）Imaging finding:37 patients were single lesions,23 patients were multiple lesions and 11 patients were diffuse lesions.1)Single and multiple solid nodules/masses were mainly distributed in the supratentorial corpus callosum and deep brain tissues around the lateral ventricle.The peritumoral edema and space-occupying effect were mainly mild to moderate,and the local space-occupying effect in the single lesion group was more significant than that of the multiple lesion group,and the superficial brain tissue involved in the single lesion group was more common than the multiple and diffuse lesion groups.Most of the lesions were equal or slightly hyperdense shadows on CT plain scan,equal or slightly longer T1 and T2 signals on MRI,and fluid attenuated inversion recovery（FLAIR）showed equal/slightly high-intensity.The enhanced scan of most lesions was irregular mass or nodule with obvious uniform enhancement and characteristic enhancement signs may appear,such as"fisting fist sign","sharp angle sign","fissure sign","butterfly sign","umbilical depression","satial lesions","satellite lesions",etc.A few lesions showed heterogeneous enhancement and a"hard ring sign"was seen.The occurrence rate of the characteristic enhanced signs"fisting fist","fissure sign","sharp angle sign"and"umbilical depression"on the enhanced MRI scan of the single lesion group was higher than the multiple lesion group.The most of lesions showed slightly hyperintensity on diffusion weighted imaging（DWI）and apparent diffusion coefficient（ADC）.Magnetic resonance spectroscopy（MRS）mostly presented a marked increase in Cho/Cr and decrease in NAA/Cr,and there may be towering Lip peaks and inverted Lac peaks.The ratio of NAA/（Cr+Cho）and NAA/Cr of the tumor parenchymal area and the proximal edema area around the tumor were significantly lower than those of the contralateral normal brain tissue,while the Cho/NAA and Cho/Cr in the tumor parenchymal area were significantly higher than the proximal edema area around the tumor and the contralateral normal brain tissue.¹⁸F-deoxyglucose(¹⁸F-FDG)positron emission computed tomography/x-ray computed tomography（PET/CT）examination showed that the most of lesions were obviously uniform high-uptake.2)Eleven patients of the diffuse lesion group had a diffuse lesion of the deep white matter of the cerebral hemispheres,involving the supratentorial and subtentorial,deep and superficial brain tissues,brainstem and spinal cord were more common than the single lesion group.The lesions were showd iso-density or slightly hypodense shadows on CT plain scan.MRI showed slightly longer T1 and T2 signals,FLAIR showed slightly high-intensity,and the density or signal of lesions were often heterogeneous in most patients without localized mass formation.The enhanced scan may have no enhancement or irregular flocculent,patchy mildly uneven enhancement in the early stage of the lesion.The early stage of the lesions range was small,limited and asymmetric in five patients（45.45%）,and the number of lesions increased in subsequent disease progression with a wide range and the degree of enhancement increased to varying degrees.The lesions area was significantly shrunk and the degree of enhancement was reduced in a short term after hormone impact therapy in three patients（27.27%）,but the disease was easy to occur repeatedly and worsen progressively.The first DWI showed that the spread of the lesions in eight patients（72.73%）was not restricted.Five patients underwent MRS examination presented a marked increase in Cho and decrease in NAA,including an increase in Lip peak in the later period of 3 patients（60.00%）and an inverted Lac peak in one patient（20.00%）.One patient（33.33%）showed no abnormal in the lesions uptake,and 2 patients（66.67%）showed slightly increased uptake in 3 patients underwent ¹⁸F-FDG PET/CT examination.（3）Prognostic factors and survival time:1)Multiple or diffuse lesions,moderate to severe peritumoral edema,Cho/Cr>2.58 and Cho/NAA>1.73 can reduce the median survival time of PCNS-DLBCL patients.2)Age>60 years old,Eastern Cooperative Oncology Group performance status（ECOG PS）score≥2 points,elevated serum lactate dehydrogenase,Bcl-6 positive and elevated cerebrospinal fluid protein can significantly reduce the patient’s median survival time.Age,ECOG PS and serum LDH were independent influencing factors of PCNS-DLBCL patients.3)The median survival time of PCNS-DLBCL patients with combined chemoradiotherapy and the use of rituximab was significantly longer than that of patients without combined chemoradiotherapy.Conclusions:（1）The clinical manifestations of PCNS-DLBCL are non-specific.The imaging manifestations of typical parenchymal masses have certain characteristics,the diffuse lesions are rare and the imaging manifestations are variable.The reasonable combination of multimodal imaging examinations can help improve their positive diagnosis rate.（2）Multiple or diffuse lesions,moderate to severe peritumoral edema,Cho/Cr>2.58 and Cho/NAA>1.73 are poor imaging prognostic factors for PCNS-DLBCL patients.（3）Age>60 years old,elevated serum lactate dehydrogenase,ECOG PS≥2 points,elevated cerebrospinal fluid protein and Bcl-6 positive are the poor clinical prognostic factors for PCNS-DLBCL patients,of which age>60 years old,ECOG PS≥2 points and elevated serum lactate dehydrogenase are independent poor prognostic factors.（4）The prognosis of PCNS-DLBCL patients with different treatment methods differs greatly.The combined chemoradiotherapy and the use of rituximab can significantly prolong the patient’s Overall survival.