Central neurocytoma is a rare intraventricular glioneuronal tumor. It can occur at any age but is more common in young adults [1],[2],[3]. A histologic investigation commonly demonstrates monomorphic round cells tumors in a fibrillar background, which can be confused with several other tumors depending on the topography and clinical data. Thus, additional techniques are often required for diagnostic accuracy. We report a case of central neurocytoma to highlight the anatomoclinical particularities and the diagnostic difficulties in a laboratory with limited resources.

The study was carried out on a 35-year-old patient who was admitted for headaches of increasing intensity, walking disorders, weakness in all four limbs, genital sphincter disorders, and seizures. The clinical examination found a preserved general condition with a Glasgow score (GCS) of 15, an intracranial hypertension syndrome, a kinetic cerebellar syndrome, spastic tetraplegia, and anesthesia going back to the sixth thoracic vertebra. An MRI revealed a heterogeneous left cerebellar lesion with overlying hydrocephalus and a hypervascularized thoracic spinal cord lesion ranging from the seventh to the eighth thoracic vertebra. However, a direct correlation or link between the two lesions was established. Only the cerebellar lesion was subjected to a surgical operation and not the spinal cord lesion due to technical platform insufficiency. The fleshy component was intensely enhanced after the injection of the contrast agent. The standard histological examination of the cerebellar lesion found a tumoral proliferation consisting of more or less monomorphic cells, small to medium in size, pale cytoplasm, and a rounded or ovoid nucleus, with fine chromatin, sometimes nucleolated, without atypia, or obvious mitotic activity. Mitoses are evaluated at less than one mitosis per 10 fields at 400 magnification. These cells were arranged in small clusters or cords surrounded by a large network of fine capillaries. There were a few congestive vessels, and in places, there was a pseudocystic appearance; there was no tumor necrosis (Figure 1). In the periphery, there was healthy cerebellar parenchyma. These morphological aspects also made it possible to suggest the diagnosis of hemangioblastoma of the cerebellar region, which led to an IHC study for better diagnostic accuracy and possible molecular classification. As neuronal and glioneuronal antibodies were unavailable for this study, the paraffin blocks were sent to a pathological anatomy laboratory in North Africa for additional immunohistochemistry. In the IHC study, the tumor cells did not express the anti-HHV8, CAIX, CD34, and GFAP antibodies, thus invalidating the diagnostic hypothesis of hemangioblastoma. On the other hand, these tumor cells intensely and diffusely expressed anti-NSE and anti-Synaptophysin antibodies, allowing the diagnosis of WHO grade 2 neurocytoma of the cerebellar region (Figure 2).

The progression was further confirmed by headaches and convulsions two (02) months after the surgery. The CT scan at four (04) months after the procedure showed tumor continuation. The patient died eight (08) months after the surgery.

Central neurocytoma is a rare glioneuronal tumor that was first described in 1982 by Hassoun et al. [1]. It is a pathology of young adults aged between 20 and 40 with an average age of 30 years, affecting both sexes equally [1],[2],[3],[4]. Although the age of our patient (35 years old) is within the range described in most studies, the location remains unusual [4],[5],[6],[7],[8],[9]. Indeed, central neurocytoma is typically described as an intraventricular tumor (third ventricle and lateral ventricle). It often develops from the septum pellucidum, buds in the lateral ventricles, and frequently obstructs the foramen of Monro [1],[3],[8],[10]. Extraventricular and intramedullary localizations have been reported by some authors [11],[12],[13]. Intra-parenchymal localizations outside the ventricles are exceptional. And for Hassoun et al. most of the reported cases of central neurocytomas of intra-parenchymal development would in fact correspond to dysembryoplastic neuroepithelial tumors (DNTs) [1].

Neurocytoma is classically revealed by symptoms of intracranial hypertension (headaches, nausea and vomiting, drowsiness, both impaired vision and consciousness, and hydrocephalus). These clinical symptoms (HIC) are related to the effect of the tumor mass and cerebrospinal fluid (CSF) outflow obstruction [4],[5],[7],[8],[12],[13],[14],[15]. In addition to the intracranial hypertension syndrome found in our patient, the clinical examination found a kinetic and static cerebellar syndrome, spastic tetraplegia with predominantly crural anesthesia going back to the 6th thoracic vertebra (T6), and genital sphincter disorders. The cerebellar syndrome in our patient could be explained by the cerebellar location of the tumor. Other symptoms, such as static paraplegia and sphincter disorders, could arise from the hypervascularized spinal cord lesion of T7–T8, as shown by the MRI.

Based on histological analysis, the differential diagnosis of central neurocytoma comprises all intraventricular tumors, ependymoma, oligodendroglioma, choroid plexus papilloma, and hemangioblastoma. Fayçal et al., out of twelve (12) confirmed cases of central neurocytoma, concluded that there were 2 cases of ependymoma and one (01) case of papillary glioneuronal tumor based on standard histology. These data show the importance of IHC analysis to confirm the diagnosis of central neurocytoma. In our case, it was the first morphological diagnostic discrepancy. Indeed, on a purely morphological level, the main differential diagnoses of neurocytoma are oligodendroglioma, ependymomas and subependymomas, astrocytomas, and to a lesser extent, hemangioblastoma [7],[8],[16]. Different approaches, including epidemiology (young adult male), imaging (heterogeneous cystic and fleshy tumor, hypervascularized with contrast uptake), and topography (cerebellar region), the main probable diagnoses are metastasis, hemangioblastoma, astrocytoma, and ependymoma. In our case, faced with a tumor located in the cerebellum, with small to medium-sized cells of diffuse architecture without epithelial component, we first thought of hemangioblastoma. In the microscopic observation, there were many capillaries of varying sizes that were separated by more or less extensive bays or ranges of vacuolar cells with rounded or elongated nuclei. These tumor cells often had a spongy appearance due to the abundance of intracytoplasmic vacuoles. A fine network of reticulin fibers surrounded the capillaries and tumor cells (Figure 1). These cells were long considered as derived from endothelial cells of capillaries; hence the classic term “vascular tumors” and their origin remains unclear.

The diagnosis was rectified by IHC examination. This examination makes it possible to make a definitive diagnosis due to the anti-NSE (neuro-specific-enolase) and antisynaptophysin antibodies (the latter not marking either the oligodendroglioma or the ependymoma) and the negativity of the vascular and glial markers. Indeed, central neurocytoma is a regular round-cell tumor presenting neuronal differentiation with synaptophysin expression but not chromogranin or neurofilament [5],[8].

The prognosis following the surgery of the tumor is excellent in the event of complete macroscopic surgical excision. Similarly, the prognosis after the surgery in the event of incomplete resection is generally good because tumor regrowth is very slow (“inactivity” is sometimes possible for 15–20 years) [4],[7],[8]. Headaches can be persistent for many years due to scarring trauma after the surgery [4]. The probability of recurrence is approximately 20% in the event of macroscopically complete resection [8],[15],[17],[18],[19]. In the study by Fayçal et al., the immediate postoperative course was simple in 75% of cases. Five-year survival was 83% of cases in their series. No recurrence has been reported [4]. In the study by Peltier et al., the postoperative course was simple in 52% of cases [19].

Our patient’s evolution was marked by headaches and convulsions two (02) months following the surgery. The computed tomography (CT) scan four (04) months after surgery showed a tumor lesion. This lesion could correspond either to a tumor remnant, an evolutionary recovery, or a tumor recurrence. It is difficult to provide a clear answer because no imaging was performed early after the surgery (D1–D2). Given the early presence of a lesion on the CT scan control, the absence of histopathological signs of malignancy, and the absence of early postoperative control imaging, we believe that the resection must have been probably incomplete. This situation, associated with the spinal cord injury, could explain the worsening of the patient’s condition until death.

The central neurocytoma shares morphological aspects with several intracerebral tumors making complementary immunohistochemistry essential for diagnostic confirmation.