Clear-cell meningioma in a 22-month-old male: a case report and literature review

Intraspinal clear cell meningioma without dural attachment: A case report and literature review

RATIONALE

Clear cell meningioma (CCM) is one of the rarest but most aggressive forms of meningioma, with a tendency to occur at a high recurrence rate. Intraspinal CCM, especially the nondura-based type, is even rarer than the intracranial CCM.

PATIENT CONCERNS

We report a case of a 45-year-old woman who presented with a 1-month history of episodic pain in the lower back and in both thighs in the front side. Femoral nerve stretch tests were positive on both sides. Magnetic resonance imaging (MRI) demonstrated an intradural tumor at the L3 level, which was isointense on T1- and T2-weighted images (WI) and homogeneously enhanced on gadolinium-contrast T1 WI.

DIAGNOSES

The space-occupying lesion was pathologically confirmed as CCM.

INTERVENTIONS

During surgery, we found that the tumor adhered to a nerve root, without dural attachment. The nerve root was partially removed to achieve complete resection.

OUTCOMES

The pain disappeared after the operation. The 1 year follow-up MRI revealed no evidence of tumor recurrence or metastasis.

LESSONS

Nondura-based intraspinal CCM is easier to completely remove, and such complete removal should be achieved during the first operation. Although the recurrence rate of this particular type of meningioma appears to be lower than that of other types, close clinical and radiological follow-up is necessary.

A Giant Nondural-Based Lumbosacral Clear Cell Meningioma Mimicking Schwannoma: A Case Report and Review of the Literature

Spinal clear cell meningiomas (CCMs) are rare and dural-based lesion usually affecting the younger population. We report the rare case of giant nondural-based spinal CCM mimicking schwannoma and review the literature. A literature search was performed at PubMed and Embase until January 1, 2020. A total of 19 cases of nondural-based spinal CCM was reported. The following relevant data were extracted: authors, publication year, patient and tumor characteristics, treatment, and outcome. The mean age of the presentation was 20.58 years. Twelve (63.16%) were female and seven patients (36.84%) were male. The most common location was lumbosacral region 15 (79%). Fifteen (79%) tumors had cranio-caudal dimension ≤2 vertebral level, and only four (21%) tumors had dimension ≥2 vertebral level. Gross total resection (GTR) was performed in 18 (95%) patients and subtotal resection (STR) in 1 patient. Recurrences were reported in five (26.14%) patients. Four of them showed recurrences within 6 months; earliest at 2.3 months in the patient had undergone STR. Our patient is 19-year-old male diagnosed with a lumbosacral intradural lesion. Craniocaudal dimension is ≥2 vertebral level shows the foraminal extension and vertebral scalloping. GTR is performed. Intraoperatively, the tumor has foraminal extension and shows attachment with right S1S2 nerve root. No dural attachment is found. Six-month follow-up magnetic resonance image shows no evidence of disease. Nondural-based spinal CCMs are extremely rare and should be kept as a differential diagnosis in young patients with giant intradural tumor, and whose radiological features suggesting of schwannoma. It affects young patients and usually involves more than one vertebral level. The chances of recurrences and metastasis are always high even after GTR; hence, close follow-up of the entire neuraxis is warranted.

Intraoperative Anatomical Findings in Pediatric Clear Cell Meningioma of the Lumbar Spine: Case Report and Literature Review

Clear cell meningioma (CCM) is a WHO classification Grade II meningioma. It is a very rare disease, of which only 41 cases of spinal cord CCM in children have been reported to date. CCMs sometimes do not have the “dural attachment” that is usually found in meningiomas, and our understanding of the origin of CCMs is therefore controversial. We hereby present a case of pediatric CCM of the lumbar spine, in which we examined intraoperatively, the detailed anatomical location of the tumor. The case is a 10-year-old boy, who presented to our hospital with a 2-month history of lower back and bilateral lower extremity pain upon waking, which gradually worsened. Lumbar spine CT and MRI revealed an intradural extramedullary tumor at the L3 vertebral level, and surgery was performed to remove it. The tumor was in close contact with the dura mater, and also in contact with the cauda equina via the arachnoid. The tumor was likely located primarily between the dura mater and arachnoid. The pathological diagnosis was CCM, with an MIB-1 index of less than 1%. His back pain and bilateral lower extremity pain improved after surgery, and he was discharged from our hospital. Postoperative radiation therapy was not performed. Based on this case, we suggest that intraoperative examination of the anatomical location of these tumors and accumulation of relevant experience are important to elucidate the embryological mechanisms of this rare disease.

Spinal Clear Cell Meningioma: Clinical Study with Long-Term Follow-Up in 12 Patients

BACKGROUND

Clear cell meningioma (CCM) is a rare histologic subtype of meningioma. The features of CCMs have commonly been based on intracranial cases. However, CCMs in the spinal cord are even rarer, and their natural history, management, and prognosis remain ill-defined.

METHODS

From January 2006 to January 2018, 12 patients with spinal CCM were treated in our hospital. The clinical features, radiologic findings, diagnosis, treatment, and outcome of these patients were analyzed retrospectively. Additionally, we performed a review of the reported data on spinal CCMs.

RESULTS

CCMs accounted for 2.8% of all the spinal meningiomas treated in our hospital. The most common localization of this disease was the lumbar region (7 of 12). The mean age at diagnosis was significantly younger than that of patients with spinal meningiomas (28.8 ± 13.4 years vs. 54.0 ± 14.4 years). During the follow-up period, 5 patients (41.7%) experienced tumor recurrence. Kaplan-Meier analysis showed that younger patients had a significantly shorter progression-free survival time than older patients. The review of the reported data showed that 55 cases of spinal CCMs had been reported. Nineteen patients (38.0%) had developed local recurrence, with a 5-year progression-free survival rate of 33.3%.

CONCLUSIONS

Spinal CCMs are extremely rare tumors with a predilection to affect younger patients and have a high recurrence rate. Although gross total resection is considered to be the optimal treatment, radiotherapy could be considered for patients who had undergone subtotal resection or for younger patients, regardless of the extent of removal. Close follow-up of the entire neuraxis for years is crucial.

Clinical Features, Treatment, and Prognostic Factors of 56 Intracranial and Intraspinal Clear Cell Meningiomas

OBJECTIVE

Intracranial and intraspinal clear cell meningiomas (CCMs) are rarely reported because of their extremely low incidence, and the current understanding of CCM is poor. The purpose of this study was to analyze the incidence and the clinical, radiologic, pathologic, and prognostic features of intracranial and intraspinal CCMs.

METHODS

Among 14,310 cases of intracranial and intraspinal meningiomas that were surgically treated between 2006 and 2016 at Beijing Tian Tan Hospital, 56 were chosen for analysis and retrospectively reviewed. To determine which parameters were associated with longer progression-free survival (PFS) and overall survival (OS), statistical analysis was performed.

RESULTS

CCMs accounted for approximately 0.39% of all intracranial and intraspinal meningiomas. Patients with CCM had a mean age of 32.3 years and there was a female predilection (20 males and 36 females). Gross total resection was achieved in 35 cases, and subtotal resection was achieved in 21 cases. All patients were followed up for 10-206 months after surgery. Twenty-six patients experienced tumor recurrence, and the median PFS was 48.0 months. The 1-year, 3-year, and 5-year PFS was 87.5%, 59.8%, and 41.8%, respectively. Twelve patients died of tumor recurrence, and the median OS was not available. The 1-year, 3-year, and 5-year OS was 98.2%, 91.3%, and 65.8%, respectively. Univariate analysis showed that total tumor removal was significantly associated with a better prognosis. Multivariate analysis confirmed only Simpson grade III and IV resection as an independent risk factor for shorter PFS. Radiotherapy mildly improved PFS after both gross total resection and subtotal resection, showing no significant difference because of the small sample size and short follow-up duration.

CONCLUSIONS

CCM is a rare subtype of World Health Organization grade II meningioma. CCM typically involves young patients and shows a female predilection and high recurrence rate. When possible, total resection is the primary and most suitable treatment for CCM. For patients with primary tumors, radiotherapy is recommended after the initial operation regardless of the extent of resection. For patients with disease recurrence, secondary surgery combined with radiotherapy might serve as an effective treatment.

Clinical features of clear cell meningioma: a retrospective study of 36 cases among 10,529 patients in a single institution

BACKGROUND

Clear cell meningioma (CCM) is a rare subtype of meningioma. We present the largest series of 36 CCMs and evaluate several prognostic factors of patient's clinical outcome.

METHODS

Thirty-six patients with pathologically confirmed CCM among a total of 10,529 meningioma patients were retrospectively reviewed.

RESULTS

CCM constituted 0.3 % of the intracranial meningiomas and 1.4 % of the intraspinal meningiomas. The male-to-female ratio (36 vs 64 %) for CCMs was similar to that for total meningiomas (28 vs 72 %) patients (chi-squared test, p = 0.3). The mean age at diagnosis of CCM patients (29.3 ± 18.4 years) was significantly younger than that of total meningiomas (49.8 ± 11.9 years) patients (t-test, p = 0). During the follow-up, 15 patients (42 %) suffered from tumor recurrence. The recurrence time ranged from 10 months to 12 years, with a median time of 29 months. Kaplan-Meier survival analysis showed that patients after total resection (Simpson grades I and II) had significantly longer progression-free survival (PFS) time than those after subtotal resection (Simpson grades III and IV) (log-rank test, p = 0.006). However, age (≤20 years or >20 years, p = 0.9), gender (p = 0.3), postoperative radiotherapy (p = 0.4), progesterone receptor staining (positivity or negativity, p = 0.2), and Ki-67 index (≤5 % or >5 %, p = 0.4) did not have significant effects on patients' PFS time.

CONCLUSIONS

The proportion of CCM in spinal meningiomas is likely to be much larger than that in intracranial meningiomas. CCMs should be resected totally when possible to decrease the risk of recurrence or prolong patient's PFS time.

SMARCE1 mutations in pediatric clear cell meningioma: case report

Clear cell meningioma (CCM) is an uncommon variant of meningioma. The authors describe a case of a pediatric CCM localized to the lumbar spine. After resection, sequencing revealed an inactivating mutation in the SWI/SNF chromatin remodeling complex subunit SMARCE1, with loss of the second allele in the tumor. The authors present a literature review of this mutation that is associated with CCM and a family history of spine tumors.

Non-dural-based spinal meningioma : the first case report of a fibrous subtype and a review of the literature

Spinal meningiomas typically adhere to the dura matter. Non-dural based spinal meningiomas are rare and most are clear cell meningiomas. We report here the first case of a fibrous meningioma with non-dural attachment. The patient was a 49-year-old female, who complained of numbness in the legs and a gait disturbance. Magnetic resonance imaging revealed a 1.7×1.4-cm mass in the C7-T1 intra-dural extramedullary space, showing peripheral gadolinium enhancement without a "dural tail sign". A complete microsurgical resection was performed. The mass was covered with a white membrane but was not adhered to the dura, and its appearance was consistent with a neurilemmoma. The histopathological diagnosis was fibrous-type meningioma. The recovery of the patient was uneventful. No surgical complications and no recurrence of the tumor had occurred at the 6-month follow-up.

Spinal clear cell meningioma in a 3-year-old: a case report

Clear cell meningioma (CCM) is an aggressive meningioma variant with a tendency to early recurrence posing a challenge to its treatment. Although spinal meningiomas are uncommon in children, this rare entity has been described as the most common variant of spinal meningiomas in the pediatric age group. We present the case of a 3-year-old with a confirmed lumbar spine CCM and discuss the problems encountered in the management of this disease.

Benign spinal meningioma without dural attachment presenting delayed CSF dissemination and malignant transformation

Benign spinal meningiomas have good prognoses, with low rates of recurrence and no cerebrospinal fluid (CSF) dissemination. However, we experienced an extremely rare case of initially benign non-dura-based spinal meningioma that showed multiple CSF disseminated lesions, which progressed for 14 years. A 29-year-old woman without neurofibromatosis presented with progressing dysesthesia in her lower limbs, low back pain, and intermittent claudication. Magnetic resonance imaging (MRI) showed an intradural extramedullary mass lesion at the Th10/11 level. The patient underwent a tumor resection. Intraoperative findings indicated that the tumor had no dural attachment. Histopathological diagnosis after gross total removal was microcystic meningioma (grade I, WHO 2007). Seven years after the first operation, other lesions appeared at the levels of Th11/12, L1, and L2/3 in MRI. These tumors were slow growing and became symptomatic; thus, a second surgery was performed 14 years after the first operation. The histopathological diagnosis was atypical meningioma (grade II, WHO 2007). Benign spinal meningiomas show CSF dissemination extremely rarely, although some authors have reported non-dura-based intraspinal clear-cell meningiomas showing CSF dissemination. However, even in cases of WHO grade I, neurosurgeons should pay attention to late CSF dissemination and malignant transformation after surgical removal of non-dura-based intraspinal meningiomas.

Non-dura based intaspinal clear cell meningioma

A 34-year-old female patient was presented with leg and hip pain for 6 months as well as voiding difficulty for 1 year. Magnetic resonance imaging revealed a well-demarcated mass lesion at L2-3. The mass was hypo-intense on T1- and T2-weighted images with homogeneous gadolinium enhancement. Surgery was performed with the presumptive diagnosis of intradural extramedullary meningioma. Complete tumor removal was possible due to lack of dural adhesion of the tumor. Histologic diagnosis was clear cell meningioma, a rare and newly included World Health Organization classification of meningioma usually affecting younger patients. During postoperative 2 years, the patient has shown no evidence of recurrence. We report a rare case of cauda equina clear cell meningioma without any dural attachment.

Pediatric spinal clear cell meningioma. Case report

In this report the authors describe a unique case of spinal clear cell meningioma in a 13-year-old girl. Clear cell meningiomas (CCMs) are not uncommon. To the authors' knowledge, 14 cases of pediatric CCM occurring in the spinal canal have been reported. Factors lending resistance to meningioma initiation and invasion are analyzed. This 13-year-old girl presented with pain radiating down her left leg. Admission MR imaging showed an inhomogeneous enhancing intradural-extramedullary mass at the L4-5 level. Resection revealed a CCM, and radiotherapy was subsequently administered. Postoperatively there has been no recurrence in > 2 years. In this paper the authors report a case of CCM and provide a comprehensive literature review on this disease. Current recommendations for its management are still debatable, especially in the pediatric population, and the authors propose an algorithm for its treatment and surveillance.

An unusual case of cervical clear-cell meningioma in pediatric age

INTRODUCTION AND BACKGROUND

A 4-year-old girl was admitted with complaints of diplegia, right lower limb monoplegia, and left lower limb monoparesia. Cervical magnetic resonance imaging revealed an intradural-extramedullary tumor at the level of C1-C2. The tumor was resected totally. Histopathologic diagnosis revealed clear-cell meningioma.

DISCUSSION

Intraspinal clear-cell meningioma (ICCM) is a rare aggressive variant of meningioma. There are only 25 cases reported to date, and only 13 of them are in pediatric age group. Of these 25 ICCM cases, only two are at cervical region. This report is the first ICCM case at upper cervical region (C1-C2) in both adult and pediatric age populations.

Meningeal tumors of childhood and infancy. An update and literature review

Meningeal derived tumors of the first 2 decades of life are often diagnostically challenging due to the wide morphologic spectrum encountered and the rarity of most individual entities. The 2 most common patterns include the dural/leptomeningeal-based mass and neoplastic meningitis. Both primary and secondary meningeal presentations may occur, either early or late in the course of various meningothelial, mesenchymal, embryonal, glial, hematopoietic, histiocytic, melanocytic, and inflammatory tumors. As in other areas of pediatric pathology, there are significant differences between this patient cohort and adults, differences which will be emphasized in this review.

Intramedullary clear cell meningioma

Intramedullary clear cell meningioma (CCM), which is more aggressive than other meningioma variants, is extremely rare. To date, only one case of such a spinal tumour has been documented. We report the first case of an intramedullary CCM originating in the thoracic region of the spinal cord.

Clear cell meningioma of the cauda equina in an adult: case report and literature review

In the pediatric population, clear cell meningiomas are more frequently intracranial than intraspinal in location. Tumors recur in up to 40% of cases within 15 postoperative months and are often managed with repeated resection with or without radiation therapy. The management strategy for adults with clear cell meningiomas involving the lumbar spinal canal (cauda equina) is less clearly defined. A 41-year-old woman presented with mild, right greater than left, lower extremity paresis. An enhanced magnetic resonance (MR) scan revealed a homogeneously enhancing intradural lesion filling the spinal canal at the L3-L4 level. Preoperative noncontrast MR studies of the brain and cervical and thoracic spine were negative. An L2-L5 laminectomy was performed for gross total excision of the intradural lesion, which was adherent to one nerve root of the cauda equina. Frozen-section diagnosis confirmed clear cell tumor. Differential diagnoses included meningioma versus renal cell carcinoma. Negative postoperative chest, abdominal, and pelvic computed tomography studies ruled out tumor of renal cell origin. Enhanced MR studies of the neuraxis proved negative. Consultations with multiple oncologists and radiation therapists recommended neither radiation nor chemotherapy following this initial surgery. She remains disease-free 1 year postoperatively. The high recurrence rate for clear cell meningiomas in children requires repeated tumor resection with or without secondary radiation therapy. Following gross total resection of lumbar tumors in adults, reserving radiation therapy for secondary recurrences provides optimal management.

Malignant meningioma as a second malignancy after therapy for acute lymphatic leukemia without cranial radiation

RATIONALE

Meningiomas in the pediatric age group are very rare tumors, comprising about 1-4.2% of all primary pediatric intracranial tumors.

CASE REPORT

We present a 17-year-old patient who suffered from an intraventricular malignant meningioma. At the age of 2 years, acute lymphatic leukemia (common ALL [cALL]) was diagnosed and successfully treated with chemotherapy. There was no cranial radiation therapy. In December 2001, 13 years after diagnosis of cALL, he complained of headache, vomiting, and walking difficulties. Magnetic resonance imaging showed an enhancing mass with cystic components in the trigone of the right lateral ventricle. The tumor was removed completely. Histological diagnosis revealed a malignant papillary meningioma. After removal of a recurrent meningioma 16 months later, he received local radiotherapy.

CONCLUSION

Pathogenetic mechanisms, treatment options, and prognosis of meningiomas and secondary malignancies of this age group are discussed.

Spinal intradural clear cell meningioma following resection of a suprasellar clear cell meningioma. Case report and recommendations for management

The authors report on 32-year-old woman with a history of a previously resected suprasellar clear cell meningioma (CCM), who returned to their institution after 3 years suffering from progressively worsening leg and back pain associated with leg weakness and bowel and bladder dysfunction. A magnetic resonance image of the thoracic and lumbar spine demonstrated a homogeneously enhancing intradural mass that filled and expanded the thecal sac. The patient underwent multiple-level laminectomies for resection of the lesion. Results of pathological studies confirmed distant recurrence of a CCM. Since its initial recognition as a rare but aggressive histological variant of meningothelial tumors, the body of literature on CCMs has grown to include more than 40 cases. Nevertheless, the natural history of this neoplastic entity remains ill defined, as are the recommendations for management. Of particular concern is the treatment of patients who have undergone subtotal resection or present with recurrence. To the authors' knowledge, the present case represents the sixth distant recurrence of CCM reported in the literature. The radiographic and histological studies are reviewed along with the current literature on this subtype of meningioma. Recommendations for surveillance and treatment are made.

Cervical clear cell meningioma mimicking a vertebral metastasis

Cervical vertebral involvement of clear cell meningioma is very rare. We report a case of clear cell meningioma in the cervical vertebral body in a 72-year old male. Seven years prior to this presentation, the patient underwent palliative surgery and posterior instrumentation for a cervical vertebral tumor at C5, which had been diagnosed as a metastatic renal cell carcinoma. On this admission, the patient presented with severe neck pain. Examination revealed hypesthesia on the left in a C6 nerve root distribution. Plain X-rays and MRI revealed an enlarging tumor in the C5 and C6 vertebral bodies. The tumor was resected via an anterior approach followed by fusion using a strut bone graft. Histological examination of the surgical specimen diagnosed a clear cell meningioma. Postoperatively, the patient achieved pain relief and resolution of the neurological deficit. At follow-up two years postoperatively, he remains asymptomatic. We emphasize that cervical clear cell meningioma with involvement of the vertebral bodies may mimic metastatic renal cell carcinoma.

Clear cell meningioma: case report and review of the literature

Clear cell meningioma (CCM) is a rare variant of meningioma. Only 17 cases have been previously reported in children. Although it has bland cytologic features, it has a higher rate of recurrence than does conventional meningioma. This variant has been reported in sites such as spinal/intradural (lumbar and thoracic), cerebellopontine angle, and supratentorial. The differential diagnosis of CCM includes microcystic meningioma, hemangioblastoma, and clear cell ependymoma. The characteristic histology and immunohistochemistry leads to the diagnosis. We present a case of a 7-year-old boy with a CCM of the cauda equina and a review of pediatric CCM.

Effect of Omeprazole on Gastric Adenosine A1 and A2A Receptor Gene Expression and Function

Adenosine has been shown to inhibit immunoreactive gastrin (IRG) release and to stimulate somatostatin-like immunoreactivity (SLI) release by activating adenosine A(1) and A(2A) receptors, respectively. Since the synthesis and release of gastrin and somatostatin are regulated by the acid secretory state of the stomach, the effect of achlorhydria on A(1) and A(2A) receptor gene expression and function was examined. Omeprazole-induced achlorhydria was shown to suppress A(1) and A(2A) receptor gene expression in the antrum and corporeal mucosa, but not in the corporeal muscle. Omeprazole treatment produced reciprocal changes in A(1) receptor and gastrin gene expression, and parallel changes in A(2A) receptor and somatostatin gene expression. The localization of A(1) and A(2A) receptors on gastrinsecreting G-cells and somatostatin-secreting D-cells, respectively, suggests that changes in adenosine receptor expression may modulate the synthesis and release of gastrin and somatostatin. Thus, the effect of omeprazole on adenosine receptor-mediated changes in IRG and SLI release was also examined in the vascularly perfused rat stomach. After omeprazole treatment, the A(1) receptor-mediated inhibition of IRG and SLI release induced by N(6)-cyclopentyladenosine (A(1) receptor-selective agonist) was not altered, but the A(2A) receptor-mediated augmentation of SLI release induced by 2-p-(2-carboxyethyl-)phenethylamino-5'-N-ethylcarboxamidoadenosine (A(2A)-selective agonist) was significantly attenuated. These findings agree well with the corresponding omeprazole-induced decrease in antral A(2A) receptor mRNA expression. Overall, the present study suggests that adenosine receptor gene expression and function may be altered by omeprazole treatment. Acid-dependent changes in adenosine receptor expression may represent a novel purinergic regulatory feedback mechanism in controlling gastric acid secretion.

Lumbosacral clear-cell meningioma treated with subtotal resection and radiotherapy

We wish to report a rare case of clear-cell meningioma in the lumbosacral region in a 34-year-old male patient who presented to us with lower back pain and leg pain. The management of the patient will be reported and histological appearance discussed. This rare tumour in a difficult anatomical position presents a challenge that requires management in a multidisciplinary fashion.

Two cases of nondura-based clear cell meningioma of the cauda equina

Clear cell meningioma is a rare disorder. We report two cases of nondura-based clear cell meningioma of the cauda equina, one in a 24-year-old male and the other in a 19-year-old female. Both patients had complained of numbness and spontaneous pain in the lower back and limbs for several months. Magnetic resonance imaging and computed tomography scanning revealed an intradural tumor in the cauda equina in each case. At surgery, a neurilemoma was suspected, because each of the tumors had displaced nerve roots and had attached to one of the nerve roots without any adherence to the dura. Light microscopy revealed that both tumors were well-demarcated with a thin capsule and consisted mainly of clear, glycogen-rich, polygonal cells with vague whorl formations, and of copious deposits of hyalinized blocky collagen in the stroma and perivascular areas. The neoplastic cells were immunopositive for vimentin and epithelial membrane antigen, but immunonegative for S-100 protein and chromogranin A. Positive nuclei for MIB-1 were very few in both cases, and PCNA-labeling indices were 12.1% and 24.7%, respectively. No local recurrence has been seen for 61 months and for 52 months, respectively.

Role of adenosine A2A receptor in the regulation of gastric somatostatin release

Adenosine has been demonstrated to inhibit gastric acid secretion. In the rat stomach, this inhibitory effect may be mediated indirectly by increasing the release of somatostatin-like immunoreactivity (SLI). Results show that adenosine analogs augmented SLI release in the isolated vascularly perfused rat stomach. The rank order of potency of the analogs in stimulating SLI release was 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS 21680) approximately 5'-N-ethylcarboxamidoadenosine > 2-chloroadenosine > R-(-)-N(6)-(2-phenylisopropyl)adenosine >1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-beta-d-ribofuranuronamide > N(6)-cyclopentyladenosine approximately N(6)-cyclohexyladenosine > S-(+)-N(6)-(2-phenylisopropyl) adenosine, suggesting the involvement of the A(2A) receptor. In agreement, 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a] [1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385), an A(2A) receptor antagonist, was shown to abolish the adenosine- and CGS 21680-stimulated SLI release. Immunohistochemical studies reveal the presence of A(2A) receptor immunoreactivity on the gastric plexi and mucosal D-cells, but not on parietal cells and G-cells, suggesting that adenosine may act directly on D-cells or indirectly on the gastric plexi to augment SLI release. The present study also demonstrates that the structure of the mucosal A(2A) receptor is identical to that in the rat brain, and that alternative splicing of this gene does not occur. A real-time reverse transcription-polymerase chain reaction assay has also been established to quantify the levels of A(2A) receptor mRNA. Results show that gastric tissues contained significantly lower levels of A(2A) receptor mRNA compared with the striatum. The lowest level was detected in the mucosa. In conclusion, adenosine may act on A(2A) receptors to augment SLI release and consequently control gastric acid secretion.

Clear cell meningioma of the fourth ventricle

Clear cell meningioma (CCM) has been identified and included in the World Health Organization classification of CNS tumors recently. CCMs are histologically characterized by sheets of polygonal cells with clear cytoplasm, which is the expression of high glycogen concentration. Compared with other variants of meningiomas, CCMs occur in younger patients and usually are located in the spinal canal and posterior fossa, the last ones mainly in the cerebellopontine angle. Some reports suggest that CCMs have high recurrence rate and potentially aggressive behavior. Poor outcome has been shown in intracranial and spinal tumor location, but indicators that predict outcome have not been established. The authors present two cases of intracranial CCMs, with excellent outcome in patients harboring tumor location (restricted to the fourth ventricle) and some clinical particular features (young age, gender, obesity, and moderate impairment of intellectual capacity). To the best of our knowledge, these are the two first reported cases of clear cell meningioma located primarily in the fourth ventricle.