Differential Proteomics Study Of Cerebrospinal Fluid In Patients With Intracranial Germ Cell Tumors

PART 1:Clinical characteristics and etiological spectrum in patients with pituitary stalk thicknessObjective:The etiological spectrum of pituitary stalk thickness(PST)is broad,but pathological samples from pituitary stalk are rarely obtained,thus presenting a diagnostic challenge.This study was to summarize various etiologies of PST.Methods:In this retrospective study,patients with MRI confirmed PST seen at Peking Union Medical College Hospital from January 2014 to May 2017 were included.Clinical data including onset symptoms,laboratory tests,imaging study,operative and pathological data were collected.Results:322 patients with PST were identified,with female-to-male ratio 1.24:1.The median age at diagnosis was 29.0 years(range:3.0-83.0 years),and 32.9%were younger than 20 years.Diabetes insipidus was the onset symptom in 59.3%patients.69.3%patients had at least one anterior pituitary hormone deficit.Compared with isolated pituitary involvement,lesions expanding upward to hypothalamus were associated with higher risk of panhypopituitarism(pituitary stalk + hypothalamus + pituitary:OR=14.0,p<0.001;pituitary stalk + hypothalamus:OR=13.4,p<0.001).Of the 133(41.3%)patients with confirmed diagnoses,neoplasm(n=72,22.4%),inflammation(n=40,12.4%)and congenital anomalies(n=16,5.0%)were the leading causes.Intracranial germ cell tumor(65.9%)was the most common cause among pediatric and young teenage patients,while Langerhans cell histiocytosis(16.9%)and metastatic malignancy(15.7%)were the leading causes among adult patents.Of 54 idiopathic PST patients,after 11.7�7.6 months follow-up,15(27.8%)were seen pituitary stalk shrink to nonnal size,8(14.8%)were seen a decrease in the thickness of pituitary stalk,27(50.0%)was seen no obvious change,while the rest 4(7.4%)patients was seen progression of pituitary stalk lesion.Spontaneous remission rate was higher in adult patients than pediatric and young teenage patients.Conclusion:PST is highly heterogeneous,among which neoplasm,inflammation and congenital anomalies are the most common causes.It's difficult to differentiate these diseases apart in terms of clinical presentation and imaging characteristics.Dynamic MRI follow-up is warranted,and diagnosis is still dependent on pathological biopsy currently.PART 2:Cerebrospinal fluid differential proteomics study in intracranial germ cell tumorObjective:To explore the value of cerebrospinal fluid(CSF)proteomics in the diagnosis of intracranial germ cell tumors and to find potential markers in CSF.Methods:CSF was collected from patients diagnosed with intracranial germ cell tumors(study group:N=21)and other confirmed diagnoses(control group:N=9)related to pituitary stalk thickness from November 2013 to April 2017 in Peking Union Medical College Hospital.Differential proteins were analyzed by Orbitrap data independent acquisition(DIA)liquid chromatography tandem mass spectrometry(LC-MS/MS).Expression of p-Akt(Ser 473),p-mTOR(Ser 2448)and PTEN in germinoma tissue was examined by immunohistochemistry.Results:1002�131 proteins were quantified in each CSF samples on average.Proteins with fold-change>2 and p value<0.05 were selected as differential protein.23 differential proteins in CSF were identified comparing pure germinoma and control group,among which 13 proteins were up-regulated while 10 were down-regulated.ROC analysis revealed that of the differential proteins,21 proteins could differentiate intracranial pure germinoma with other diseases significantly(p<0.05),among which,the area under curve for CHST10,PCDHGC5,MANSC1,PCDH10,BAI1,NLGN2,CX3CL1,CDH8,F13B,C5 and MIA was above 0.9(p<0.05).FAT2,BAI1,TAC1,NLGN2,LBP and IGKV3-20 were independent with age and sex(p>0.05).FAT2 elevation in CSF had a trend in association with dissemination(p=0.089).In comparison with outside databases,only 2 common differential proteins were identified compared with differential proteins found by tissue proteomics in our previous study,and differential proteins in CSF were not involved in KIT/RAS,PI3K/Akt/mTOR or Cyclin/CDK-RB-E2F pathway.Regarding protein expression in the tissue of germinoma,p-Akt(Ser 473)was mildly positive in the cytoplasm and nucleus in tumor cells,p-mTOR(Ser 2448)was expressed both in tumor cells and surrounding lymphocytes,while PTEN was also expressed in tumor cells and lymphocytes but dominated by lymphocytes.Conclusion:Differential proteins are potential markers to differentiate intracranial germinoma with other pituitary stalk lesions.