Central Neurocytomas is a borderline benign/malignant lesion and surgery is suggested as the primary treatment for it [1, 2]. CNCy comprise only 0.1–0.5% of all primary brain tumors [1–4]. The overall survival (OS) of CNCy is mostly linked with, a) the amount of maximal safe resection and b) the outcome of surgery (p < 0.05) [1–3, 8]. They are more likely to be female, young, and of non-white race . Inferior septum pellucidum and anterior lateral ventricles are the most common locations with lobulated / multibleb appearance due to intra-tumoral cyst formation as in our case [1, 7].
They are low-grade (WHO Grade II, 2000 classification) lesions arising from progenitor bipotential cells with capability of differentiating along the glial or neuronal lines arising from the subependymal layer of the septum pellucidum or the ventricular walls. Neurocytomas can be extra-ventricular, however, the term CNCy is reserved exclusively for intraventricular lesions . On MRI, the solid components of the tumors are hyperintense in T1- and T2-weighed images as in our case. Long TR sequences show cystic changes in two-thirds of the cases and broad attachment to the ventricular wall or septum is almost always detectable as shown in the fig. c in this case.
To the best of our knowledge, no common risk factors for these two diseases are discovered. Several mechanisms have been suggested for triggering development of multiple primary brain tumors of different histology in a patient [6, 7], but the etiology remains unknown. Different hypotheses suggested for development of concurrent/ adjacent double tumors may be summarised as: 1) they occur because of activation of the signaling pathways of receptor tyrosine kinases, 2) one tumor may secrete a growth factor that initiates growth of another lesion. [6, 7] The occurrence of upregulation of proinflammatory cytokines and the angiogenic factors necessary for growth of both lesions.  We did not have the facility to evaluate the signalling microarrays and factors. Our case occurring along with an AVM in a young girl can raise/suggest the hypothesis that both could have been of congenital origin.
Regarding the best surgical approach in this case, the transcortical approach to the tumor was selected according to its size and location and the surgeon's preference. This approach had several advantages in our case, including easy access to the lateral ventricle by using a short route, a reduced risk of damage to the fornix, and avoiding the parasagittal veins and pericallosal arteries. Surgery was uneventful in this case and hydrocephalus was managed with VP shunt revised only once during the follow up period and no adjuvant therapy.
Modern management of CNCy has been planned by several institutional case series. Outcomes of interest have been the progression free survival (PFS) and OS from the date of first surgery as in our case which has been long enough possibly to be considered cure. Given the rarity of CNCYs, the optimal management strategies are still evolving. Both fractionated conventional radiotherapy and stereotactic radiosurgery are suggested for cases with residue or recurrences. There also exists marked heterogeneity in chemotherapy used to treat CNCYs and Temozolomide is incorporated into treatment regimens in the setting of tumor recurrences. [1–3, 6].
It is reported that there is a higher incidence of CNCy in Korea, India, and Japan, possibly attributed to genetic differences among racial groups but we are not aware of this in Iran [3, 7]. The higher incidence in these Asian countries, make CNCy an important consideration when dealing with intraventricular tumors in these contexts.
Combination of CNCy with another tumor and aneurysm in CNS have been anecdotally reported in the literature (Table 1) . Our case occurring along with an AVM could raise the hypothesis that both could have been of congenital origin and without any flow associated mechanism. These unusual associations suggest a common genetic basis for pathologies of seemingly different and obscure origin. To the best of our knowledge, no common risk factors for these two diseases are discovered. Several mechanisms have been suggested for triggering development of multiple primary brain tumors of different histology in a patient, and the etiology remains unknown [6, 7]. Some believed that concurrent adjacent double tumors occur because of activation of the signaling pathways of receptor tyrosine kinases or, one tumor may secrete a growth factor that initiates growth of another lesion [6, 7]. To our idea, this presentation can still be a co-incidence.