Introduction
CNS tumors comprises less than 3 % of total body tumors1. The annual incidence of primary malignant brain tumors is ~3.7 per 100,000 for males and 2.6 per 100,000 for females2,3. The incidence in India ranges from 5 to 10 per 100,000 population with increasing trend and accounts for 2% of total malignancies4,5.
The WHO classification of brain tumors in 2007 comprised of major groups as Tumors of neuroepithelial tissue, Tumors of meninges, Lymphomas and Haematopo ietic neoplasm, Germ cell tumors, Tumors of sellar region, Metastatic tumors & Tumors of cranial and paraspinal nerve6. In 2016 WHO proposed the new classification of CNS tumors. For the first time, WHO classification used molecular parameters in addition to histology to define various tumors7.
Astrocytomas (38.7%) were the most common primary tumors with the majority being high-grade gliomas (59.5%) for adults in India8. The most common primary paediatric brain tumors were astrocytic tumors (34.7%), followed by medulloblastoma and supratentorial primitive neuro -ectodermal tumors (22.4%), craniopharyngiomas (10.2%) and ependymal tumors (9.8%). The most common astrocytic tumor was pilocytic astrocytoma9.
Reports in the literature indicate that worldwide variations exist in the pattern of CNS tumors with respect to Age, incidence, anatomical locations, gender preferences, and histological types.
Hence, epidemiological data on CNS tumor is useful for future research for specific locality. In India, hospital based registration system form the bulk of the data for estimating the disease load in the community. Until date, no epidemiological study on CNS tumor was done for central India region. The aim of this study is to find the spectrum to CNS tumors in our setup and compare with other studies.
Materials and methods
This is a retrospective observational study conducted during the period of 2014 to 2019 in MGIMS, Sevagram. The inclusion criteria consist of all CNS tumor cases diagnosed in neurosurgery department, which were histopathologically proven. The exclusion criteria consist of inoperable cases, undiagnosed cases and tumor of peripheral nerves. Total 168 cases fulfilled the above criteria and were included in the study.
Results
This retrospective study was conducted for period between Jan 2014 and Feb 2019, in MGIMS Sewagram. Total 168 histopathological proven tumors were included in the study. Of total CNS tumors 142(84.4 %) comprised of intracranial tumors and rest 26(15.4 %) comprised of spinal tumors. Paediatric tumor (<19 years) comprised of total 7.14% percent of the tumor. The CNS tumor had slight male preponderance with M :F ratio of 1:1.24. Age of patient varies from 2 to 78 years Figure 1 with average age of 41.3 years. For paediatric CNS tumor the M :F ratio was 1:1 with average age of 12.25 years. Tumor were classified according to WHO classification 2007.
Most common tumor found was of Neuroepithelial tissue (36.9 %) other being tumors of meninges (26.78%), tumor of cranial & spinal nerves (20.24 %), sellar region (8.93 %), metastatic tumors (5.95%) & Germ cell tumor ( 1.19%) (Figure 2 , Table 1 ).
Neuroepithelial tumors ( 62 cases) comprised mainly of astrocytoma (48 cases, 77.41% ), others being oligodendroglial tumors (4 cases, 6.45%), embryonal tumors (3 cases, 4.83%), ependymal tumors (3 cases, 4.83%), mixed neu ronal-glial tumors (2 cases, 3.22 %), oligoastrocytic tumors (1 case, 1.61 % ) & choroid plexus tumor (1 case, 1.61%).
Among astrocytic tumors (48 cases), Glioblastoma (23 cases, 47.92%) was most common followed by diffuse astrocytoma (14 cases, 29.17 %), anaplastic astrocytoma (8 cases, 16.67%) & pilocytic astrocytoma (3 cases, 6.52 ). WHO grade IV was the most common astrocytic tumor (Table 2). For astrocytic tumors, average age of presentation was of 38.51 years. For glioblastoma, average age of presentation was 50.5 years, with M:F ratio of 2.2 :1.
Tumors of meninges constitutes (45 cases) 26.8 % of total CNS tumors. Meningioma comprised of (44 cases) 97.3% while hemangiopericytoma comprised of (one case) 2.7%. Average age of presentation of meningioma was of 44.1 years with M:F ratio of 1 :1.32. WHO grade I comprised of 95.45% while WHO grade II comprised of 4.55% of total tumors.
Tumors of sellar region comprised of (15 cases) 8.9% of the total CNS tumors.
Secondaries in brain constitutes (10 cases) 5.9 % of total CNS tumors with average age of 50 years with M:F ratio of 1:1.25. The most common cause of secondary was primary lung tumor followed by breast tumor (Figure 3).
Spinal tumor s consists of (26 cases) 15.4 % of tumors. Average age of presentation of spinal tumor was 42.1 years with female preponderance (M:F = 1:1.36). Most common spinal tumor was schwannoma (15 cases) followed by meningioma (7 cases).
In our study paediatric tumor comprised of (12 cases) 7.14% of the study population. The mean age of presentation was 12.25 years with M :F ratio of 1:1. The most common tumor being Astrocytoma (25%) and medulloblastoma (25%).
Table 1
Histopathology subtypes of diagnosed brain tumors
Table 2
| WHO Grading | No.of cases |
| Grade I | 3 |
| Grade II | 14 |
| Grade III | 8 |
| Grade IV | 23 |
| Total | 48 |
Relative frequency of astrocytoma according to WHO grading
Table 3
| Types of meningioma | Present study(%) |
| Meningothelial | 47.72 |
| Psammomatous | 13.63 |
| Transitional | 13.63 |
| Fibroblastic | 11.36 |
| Angiomatous | 9.09 |
| Atypical | 4.54 |
Histopathology of meningioma
Table 4
| Histopathology | Number of cases |
| Schwannoma | 15 |
| Meningioma | 7 |
| Ependymoma | 3 |
| Metastasis | 1 |
| Total | 26 |
Histopathology of Spinal tumor
Discussion
Tumor of CNS are rare and comprised of <3 % of total body tumor s. In our study out of 168 tumors, 142(84.6 %) were intracranial tumors while 26 were spinal tumors (15.4%). Percentage of intracranial tumor was lower than other publications by Jalali R et al (95%)8, Suh YL et al (93.5%)10 & USA data (94.3%)11.
In our study, the most common tumor was astrocytic tumors (28.57%), out of which the majority were glioblastoma (47.92%) followed by diffuse astrocytoma (29.17 %). In a study done by Dasgupta A et al, Astrocytomas (38.7%) were the most common primary tumor s with the majority being high-grade gliomas (59.5% )12. Ghosh et al13, Jalali and Datta8 and Patty14 also reported astrocytomas to be the commonest tumor. Study by Collins vp et al15, Das et al16, Suh YL et al10 and Lee et al17 reported meningioma as the most common tumor. Our st udy shows Meningiomas as second commonest tumor (26.19%). Iyengar and Chandra18, Wen-quing et al19 and Patty14 made similar observations. Our study had female preponderance with M:F ratio of 1:1.3 for meningioma. In other study by Rohringer et al20, M:F ratio was 1:2. The most common histopathological entity encountered in our study was meningothelial variant (47.72%) Table 3 . Sangamithra et al21, Nasrin Samadi et al 22, Gursan et al23, all reported menigothelial as the most common variety. Spinal meningiomas comprised of 15.9% of total meningiomas in our study. In study done by Solero CL et al spinal meningiomas consist of 7.5-1 2.7 % of all CNS meningiomas. In our study the most common location, for spinal meningioma was thoracic spine which is similar to the other study reported 24,25,26 .
Tumor of sellar reg ion comprised of 8.9%, which was slightly higher than the study conducted by Jalali et al (8.3 % )8 and Goh et al (8.6%)27.
Secondaries in brain constitutes 5.9 % of total CNS tumors. It goes similar to study of Suh et al (6.0% )10 but higher than that of Lopez-Gonzalez et al(4%)28. Indian study by Jalali et al8 repoted 11.6% as secondaries in brain, which was significantly higher than our study. The most common cause of secondary was primary lung tumor followed by breast tumor. It was similar to the study conducted by Singh et al29.
Spinal tumor comprised of 15.4 % of tumor. The most common spinal tumor was schwannomma (57.69%) followed by meningioma (26.92%) Table 4 . Albanese and Platania, 2002, reported that spinal Intradural extramedullary tumors account for 2/3rd of all intraspinal neoplasms and are mainly represented by meningiomas (25 – 46%) and schwannomas30. Schellinger et al reported that the most common histologic types were meningiomas (29%), nerve sheath tumors (24%), and ependymomas (23% )31. Cause of this variation is not known. It could be due to the small sample size or due to the variation in local population.
Paediatric tumor comprised of 7.14 % of population. The most common paediatric tumor was Astrocytoma (25%) and medulloblastoma (25%). Chen et al found astrocytomas to be leading tumors (29.2%) in this age group32. Similarly, study by Jain et al indicated that astrocytomas averaged 34.7% (range 22.3-46.7%), were the commonest paediatric tumors in India followed by medulloblastoma and PNETs (22.4%)9.
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