Central neurocytoma: a case study.
A previously healthy 17-year-old high school senior and football player awoke early in the morning on two different occasions with a pounding occipital headache and vomiting. On the second occasion his tongue and left arm became numb, which lasted for only a few minutes. He continued to have headaches when changing positions. The next day, he attended football practice and while lifting weights experienced severe headache and vomiting. The headache became constant, and he experienced blurry vision. The patient sought medical attention from his primary care physician, who made immediate referral to a neurosurgeon.
The physical examination revealed a young, apparently healthy, well-oriented Caucasian male with normal vital signs. He was slightly photophobic. His neurologic abnormalities consisted of bilateral papilledema, dilated but equal and reactive pupils, abnormal rapid alternating movement on the left, and drift in the left upper extremity. He had increased deep tendon reflexes on the left but no pathological reflexes.
Diagnostic scans were obtained. The computed tomography (CT) scan revealed a large, irregular, multilobulated, partially calcified enhancing mass in the medial aspect of the right cerebral hemisphere. A magnetic resonance imaging (MRI) scan revealed a large 7 x 7 x 7-cm multilobulated, partially cystic, partially solid tumor in the medial aspect of the right cerebral hemisphere with shift of the midline toward the left (Fig 1).
[FIGURE 1 OMITTED]
The lesion appeared to be mostly within the right lateral ventricle, although the tumor extended into the right thalamic region and occupied almost a third of the volume of the right hemisphere. It produced obstruction of the occipital and temporal horns of the right lateral ventricle, with marked dilatation of the atrium of the right lateral ventricle. Enhancement was seen in the periphery of the tumor. No masses were seen in the left hemisphere, but deformity was present due to the midline shift.
A magnetic resonance spectroscopy (MRS) scan was performed. MRS is a scan that is performed in the magnetic resonance scanner and detects biochemical metabolites of normal and abnormal tissue (McBride et al., 1995). The spectroscopic analysis of the normal brain showed a normal biochemical spectrum. The abnormal enhancing tissue showed a decrease in the amount of N-acetylaspartate (NAA) in relationship to choline and creatine, indicating that the lesion contained a mixture of neuronal tissue and neoplastic tumor. After testing, the patient was admitted to the hospital for intravenous steroid and hyperosmolar therapy and close neurological assessment prior to surgery.
A right occipital-parietal craniotomy was performed using computer-guided assistance. The brain was under extreme pressure and the ventricle was tapped prior to opening the dura. The tumor had multiple cystic areas, and the walls of the ventricles were involved. The tumor was very friable and bled easily. The frozen section indicated that the tumor was a low-grade glioma.
The patient deteriorated neurologically 3 days after surgery. His level of consciousness decreased, left paresis worsened, and he developed apnea and bradycardia. The MRI revealed increased cystic mass and the patient underwent re-operation for gross total removal of the cystic tumor.
The tumor specimen had extensive areas of calcification, and there were areas of hypercellularity with zones of necrosis; nuclear anaplasia and mitoses were evident. The final pathology report indicated a central neurocytoma (CN), WHO grade II. Immunoperoxidase staining for neuron-specific enolase (NSE) was positive. The glial fibrillary acidic protein (GFAP) was negative. The MIB-1 labeling index (LI), a proliferation marker, was greater than 2%. The anaplastic nuclear features accompanied by mitoses, vascular proliferation, and area of necrosis suggested that the tumor may have a potential for more aggressive growth, local recurrence, or both.
Postoperatively, he had a significant left hemiparesis and a left visual field deficit. No additional treatment was required at that time. He was discharged from the hospital to a rehabilitation center where he continued to improve. His 6-month follow-up MRI scan was stable, and his left hemiparesis has continued to improve.
The patient graduated from high school 10 months after surgery. He recently worked in an office and is attending college. He is walking with a cane, and his left hemiparesis continues to improve.
Neurocytomas are rare intraventricular brain tumors that affect young adults. Just over 100 cases have been reported since CN was first described by Hassoun et al. in 1982. Patients generally present with CN in their 30s. There appears to be a higher incidence in males than in females (Kim et al., 1996; Schild et al., 1997). Patients usually present with signs and symptoms of obstructive hydrocephalus, such as headache, nausea, visual and mental disturbances, and papilledema (Enam & Rock, 1999).
The neoplasm is of neuronal origin (Hassoun et al., 1982). CNs account for less than 1% of all central nervous system tumors (Kaye & Laws, 2001). Most neurocytomas are located within the ventricular system at or near the midline; hence the term "central" is used (Goergen, Gonzales, & McLean, 1992; Hassoun et al., 1982). However, extraventricular neurocytomas have been reported, and the term cerebral neurocytoma has been used to describe these locations as well (Nishio, Takeshita, Kaneko, & Fukuri, 1992). In most cases, the tumor arises in the body of the lateral ventricle, in the area of the foramen of Monro. It can then extend into the third ventricle or even to the opposite lateral ventricle (Majos, Coll, & Pons, 1997). The tumor can impair drainage of cerebrospinal fluid in the lateral ventricle and cause ventricular dilatation.
CN can be confused with ependymoma or oligodendroglioma on light microscopy alone. Additional immunohistochemistry or electron microscopy is suggested (Majos et al., 1997).
Synaptophysin or neuron-specific enolase positivity on immunohistochemistry, or the presence of typical or abortive synapses, neurosecretory granules or neuritic processes on ultrastructural examination, demonstrate the neuronal lineage of the tumor cells, not found in glial tumor and support the diagnosis of CN (p. 271-272).
Radiological appearances of CN are characteristic of an entirely intraventricular, well-circumscribed tumor mass, isodense or displaying increased density on CT, and isointense or displaying a high signal on most MRI sequences, which show at least moderate contrast enhancement. The tumor generally contains an area of heterogeneous signal intensity, which represents focal cysts, calcification, or hemorrhage. Intense enhancement may be seen with gadolinium, because the tumor is generally hypervascular. Hemorrhage into the tumor is not common, but can be a useful tool for differentiating CN from other intraventricular tumors, which have less of a tendency to bleed (Chang et al., 1993; Goergen et al., 1992; Kaye & Laws, 2001; Kim et al., 1996; Osborn, 1994; Wichmann, Schubiger, Deimling, Schenker, & Valavanis, 1991).
Because the lesions tend to obstruct the foramen of Monro, patients present with signs and symptoms of noncommunicating hydrocephalus. Symptoms may develop rapidly or progress slowly and may include severe pounding headaches; visual changes such as blurring, visual field deficits, or double vision; and nausea, vomiting, or both. Papilledema and mental disturbances such as lethargy and irritability can be seen (Kaye & Laws, 2001; Schild et al., 1997).
Gross total surgical resection is the treatment of choice for CNs. Treatment is based on the degree of surgical resection and the aggressiveness of the tumor. Clinical observation and serial MRI scans are necessary for follow-up. If recurrence should occur, radiation therapy should be contemplated, but the prophylactic use of radiation in CN remains unclear (Kaye & Laws, 2001).
There are data to support the use of radiation, which may help in preventing tumor growth or reducing residual tumor in subtotal resected neurocytomas. Kim et al. (1997) reported no recurrence in two patients who underwent gross total resection and fractionated radiation therapy at 41 and 94 months, respectively, after surgery. The authors also reported that five patients who underwent subtotal resection and fractional radiation therapy experienced positive responses: Three patients had gradual tumor shrinkage at 6, 45, and 113 months, and in two patients, the tumor disappeared at 27 and 33 months (Kim et al.). Furthermore, Kim et al. reported that six patients with subtotal resection alone experienced no recurrence at 4, 33, 76, 2, 4, and 29 months after surgery. This study concluded that radiation therapy may have an effect on tumor control.
Anderson, Elder, Parsa, Issacson, and Sisti (2001) reported four cases of CN with tumor progression after surgical resection. These four patients were treated with radiosurgery. The follow-up after radiosurgery was 12 to 28 months. They reported that all four patients achieved complete response with reduction in tumor size. Anderson et al. concluded that radiosurgery was a safe and effective adjunct therapy after surgical resection of CN.
Dodds, Nonis, Mehta, and Rampling (1997) described a case of a 15-year-old boy with a large CN that was treated with chemotherapy. The tumor was massive and highly vascular, and a modest decompression was performed. Because complete surgical excision was not possible due to the size of the tumor and radiation therapy would have involved unacceptable large fields of treatment, it was decided to treat the patient with chemotherapy.
The patient completed four cycles of chemotherapy, which consisted of etoposide, ifosfamide, and carboplatin. A CT scan after chemotherapy indicated some regression of the tumor. He was followed and remained well for 22 months, at which time he developed headache, pupillary dilatation, and episodes of torticollis. A MRI scan showed enlargement of the tumor. He subsequently underwent a craniotomy for subtotal tumor resection followed by radiation therapy. He is reported well after 6 years. Dodds et al. concluded that chemotherapy may offer an alternative, especially for cases in which surgical removal is not possible.
The clinical outcome is generally good. Patients who have had adequate or complete surgical resection have an excellent prognosis with a good chance of no tumor recurrence (Erkus, Demirtas, Yegen , Zileli, & Oner, 1998). However, Mackenzie (1999) and Soylemezoglu, Scheithauer, Esteve, and Kleihues (1997) have indicated that neurocytomas with an MIB-1 LI greater than 2% have a higher chance of relapse. The MIB-1 LI is the equivalent of the Ki-67 antibody, which labels cells in the growth phases of the cell cycle (Kaye & Laws, 2001). The Ki-67 protein is associated with cell proliferation and is considered an excellent marker for determining the growth fraction of a cell population (Scholzen & Gerdes, 2000). Soylemezoglu et al. found a 22% relapse if the MIB-1 LI was less than 2%, but a 63% relapse if the MIB-1 LI was greater than 2%. Because of this finding, Soylemezoglu et al. have proposed that neurocytomas with a MIB-1 LI greater than 2% should be classified as atypical neurocytomas (Kaye & Laws, 2001; Soylemezoglu et al., 1997). Mackenzie (1999) also found a high correlation between tumor recurrence and an MIB-1 LI greater than 2%. Patients with subtotal resection and MIB-1 LI greater than 2% should be considered for radiation (Kaye & Laws, 2001).
Central neurocytoma is a rare intraventricular tumor that affects young adults. It accounts for less than 1% of all CNS neoplasms. It has a predominance in males and has features of cystic spaces and intratumoral calcifications. Intense enhancement can be seen with gadolinium because the tumor is generally hypervascular. It can impair drainage of the lateral ventricle and cause ventricular dilatation and patients often present with signs and symptoms of noncommunicating hydrocephalus. Symptoms may develop rapidly or slowly and progress to include headaches, visual changes, visual disturbances, nausea/vomiting, and mental disturbances. If symptoms progress rapidly and neurological deterioration occurs, a ventricular shunt may need to be placed to relieve intracranial pressure. Gross total surgical resection is the treatment of choice for central neurocytoma. It is not clear whether radiation is indicated for patients who have undergone gross total resection. Radiosurgery and chemotherapy may play a role in the treatment of recurrent CN. Management is based on the degree of surgical resection and tumor behavior. The clinical outcome is generally good, and patients who have had gross total surgical resection have a good chance of no tumor recurrence.
The author thanks Theodore Bernstein, MD, Lenora Gray, MD, Cathy Satter, PhD, and Pamela Sequeira, MD, of the Wallace-Kettering Neuroscience Institute for their review of the manuscript.
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Questions or comments about this article may be directed to: Jean Ruppert, MS RN CNRN, Wallace-Kettering Neuroscience Institute, 3533 Southern Boulevard, Suite 5200, Kettering, OH 45429. She is a neuroscience clinical case manager at Wallace-Kettering Neuroscience Institute.
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|Publication:||Journal of Neuroscience Nursing|
|Date:||Aug 1, 2002|
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