The Central Nervous System Primitive Neural Ectoderm Tumor The Clinical, Imaging And Pathological Study

Objective:Central nervous system primitive neural ectoderm tumor cPNET) is a rareintracranial malignant tumor, accounted for less than1%inprimary central nervous systemtumors. cPNET is a kind of highly malignant primitive neuroepithelial tumors with rapidprogression and poor prognosis. Most cPNET patients typically survive less than2years.Because cPNET has low incidence and is lack of clinically specificity, the misdiagnosisrate is high. There are only sample case studies about cPNET focusing on imaging andpathology analysis, large scale cases reports are lacking at home and abroad, so it isdifficult to have a comprehensive understanding on cPNET. To carry out a systemic studyabout cPNET on clinical, imaging, pathological and immunohistochemical characteristics,and investigate the impact on the prognosis is of vital for further study of the pathogenesisand clinical treatment.Meterials and Methods:In the study, the clinical data of22patients of cPNET were collected in the NavyGeneral Hospital from January1995to December2012, including case history, laboratorytests data, imaging data (head MRI, CT, MRS), etc. Paraffin section, HE staining and immunohistochemical analysis were routinely performed to confirm the diagnosis. Asystematic analysis was carried out about the incidence, imaging and pathological features.Taking postoperative survival time as the major prognosis index, the influence of age(years old), gender, tumor location, size, staging and treatment methods on survival timewas analyzed by single factor and multi-factor analysis method using COX regressionmodel.Results:1. clinical features:(1) the course of cPNET patients was between a few days and several months (meantime12.6weeks).(2) gender：male14, female8cases, male and female ratio was1.75:1.(3) age:2~61years, mean age was15.18years.12cases were1year~10years;5cases were11~20years; the other4cases aged32,41,43and61years.(4) signs and symptoms:15cases with increased intracranial pressure symptoms,5cases with limb weakness,6cases with epilepsy,5cases with headache alone.2.Immunohistochemicalstaining:CD99+cells was found in18cases(81.8%); synaptophysin (Syn) positive in14cases,（63.6%）; Collagen fibre acidic protein (GFAP) positive in11cases（50%）; neuronspecificity enolization (NSE) positive in9cases（40.9%）; S-100positive in5cases,（22.7%）; vimentin (Vim) positive in4cases（18.2%）; Leukocyte common antigen(LCA), cytokeratin (CK) and epithelial membrane antigen (EMA) staining was negative inall cases.3. Imaging features:(1) most lesions were located in peri-ventriclar region of frontal parietal lobe with acontour of circular, lobular or irregular. The maximum diameter was4.0~8.5cm(meandiameter was5.7cm).(2) tumor boundary was clear in15cases and not clear in7cases. T1signal was low or slightly low in17cases and isointensity in5cases.15cases showed isointensity inT2imaging,5cases showed slightly highintensity and2cases showed highintensity.(3) There was enhancement in enhanced scan, there was no peritumor edema in8cases, mild peritumor edema was found in14cases. Calcification was found in12cases.4. Survival analysis:(1) the incidence rate was higher in patients less than10years old than the adult, butthere was no obvious difference in postoperative survival time.(2) There was no gender difference about postoperative survival time.(3) tumor size had no significant effect on prognosis.(4) gross total removal achieved better prognosis than partial removal.(5)postoperative chemotherapy and radiotherapy could improve the prognosis.(6) multi-factor survival analysis showed that ventricle invasion, the degree ofsurgical resection, postoperative radiotherapy and chemotherapy had influence onprognosis.Conclusion:1.cPNET accounted for less than1%in primary central nervous system tumors that canaffect all ages, but majored in children within ten years old. the incidence was slightlyhigher in the male than the female. The age and gender had no obvious impact onprognosis.2. the main clinical manifestations of cPNET is local space-occupying effect but thereare no featured clinical manifestations. Increased intracranial pressure such as headacheand vomiting is the most common symptoms, epilepsy is also an usual clinicalmanifestation.3. lesion size had no significant effect on prognosis, but lesions involving the ventricleis an unfavourite factor for prognosis in patients with, which was related to tumormetastasis through cerebrospinal fluid (CSF).4. Surgery is the first choice. Gross total removal can achieve a better prognosis thanpartial removal. 5Radiotherapy is an important and effective adjuvant treatment, which cansignificantly improve the prognosis and should be used routinely.6. Chemotherapy is another important adjuvant therapy. combination of chemotherapyand radiotherapy can achieve better outcome than chemotherapy alone.7. multi-factor survival analysis showed that ventricle invasion, the degree of surgicalresection, postoperative radiotherapy and chemotherapy had influence on prognosis.