[Clinicopathological Features of Meningiomas in Tibet]

Objective To analyze the clinicopathological features and immunohistochemical expression of meningiomas in the Tibetan population in Tibet,and improve the understanding of meningiomas. Methods The clinical and pathological data of all the meningiomas diagnosed by pathology in Tibet Autonomous Region People's Hospital from April 2013 to March 2021 were analyzed retrospectively.All the cases underwent immunohistochemical staining of trimethylation of lysine 27 on histone H3 (H3K27me3),mucin 4 (MUC4),somatostatin receptor 2 (SSTR2),progesterone receptor,epithelial membrane antigen,glial fibrillary acidic protein,vimentin,S-100,P53,and Ki-67.The histopathological features and the staining results were observed under a light microscope. Results A total of 116 cases of meningiomas were included in this study,with the male-to-female ratio of 1.0∶2.6 and the age of 4-73 years.The main clinical symptom was headache.The imaging examination showed that 114 cases had single lesions and 2 cases had multiple lesions.The tumors were located in the cranium (108 cases) and spinal canal (8 cases).The maximum diameter of the tumors ranged from 0.3 cm to 10.0 cm,with a mean of (5.7±2.2) cm.In terms of microscopic grading and histological types,the 116 cases included 111 cases of WHO grade Ⅰ (including 53 cases of fibrous type,20 cases of meningothelial type,24 cases of transitional type,10 cases of psammomatous type,etc.),4 cases of WHO grade Ⅱ (3 cases of atypical type and 1 case of clear cell type),and 1 case of WHO grade Ⅲ (papillary type).The immunohistochemical staining showed H3K27me3 expression absent in 9 cases (9/116,7.8%),MUC4 positive in 64 cases (64/116,55.2%),SSTR2 positive in 101 cases (101/116,87.1%).Eighty cases had follow-up results,among which 71 cases had no recurrence,while 9 cases recurred. Conclusions Meningioma is the most common tumor in the central nervous system in the pathological file of Tibet.It mainly attacks the middle-aged female patients,occupying the parasagittal sinus,falx,and convex surface of the brain.Fibrous meningioma of WHO grade Ⅰ is common,while the meningiomas of WHO grades Ⅱ and Ⅲ are rare.The expression degree of MUC4 is higher in meningothelial and transitional meningiomas but lower in fibrous meningiomas.There may be no correlation between the absence of H3K27me3 expression and prognosis.