Surgical Management of Craniovertebral Junction Schwannomas: A Systematic Review

Background: Craniovertebral junction (CVJ) schwannomas are rare, with surgery and stereotactic radiosurgery (SRS) being effective yet challenging options. We systematically reviewed the literature on CVJ schwannomas. Methods: PubMed, Scopus, Web-of-Science, and Cochrane were searched following the PRISMA statement to include studies reporting CVJ schwannomas. Clinical features, management, and outcomes were analyzed. Results: We collected 353 patients from 101 included articles. Presenting symptoms were mostly neck pain (30.3%) and headache (26.3%), with most cranial neuropathies involving the XII (31.2%) and X (24.4%) nerves. Most tumors originated from C2 (30.9%) and XII (29.4%) nerves, being extracranial (45.1%) and intradural-extradural (44.2%). Erosion of C1–C2 vertebrae (37.1%), the hypoglossal canal (28.3%), and/or jugular foramen (20.1%) were noted. All tumors were operated, preferably with the retrosigmoid approach (36.5%), with the far-lateral approach (29.7%) or with the posterior approach and cervical laminectomy (26.9%), far-lateral approaches (14.2%), or suboccipital craniotomy with concurrent cervical laminectomy (14.2%). Complete tumor resection was obtained most frequently (61.5%). Adjuvant post-surgery stereotactic radiosurgery was delivered in 5.9% patients. Median follow-up was 27 months (range, 12–252). Symptom improvement was noted in 88.1% of cases, and cranial neuropathies showed improvement in 10.2%. Post-surgical complications occurred in 83 patients (23.5%), mostly dysphagia (7.4%), new cranial neuropathies (6.2%), and cerebrospinal fluid leak (5.9%). A total of 16 patients (4.5%) had tumor recurrence and 7 died (2%), with median overall survival of 2.7 months (range, 0.1–252). Conclusions: Microsurgical resection is safe and effective for CVJ schwannomas. Data on SRS efficacy and indications are still lacking, and its role deserves further evaluation.

Radiation risk of central nervous system tumors in the Life Span Study of atomic bomb survivors, 1958-2009

Radiation exposure is among the few factors known to be associated with risk of central nervous system (CNS) tumors. However, the patterns of radiation risk by histological type, sex or age are unclear. We evaluated radiation risks of first primary glioma, meningioma, schwannoma, and other or not otherwise specified (other/NOS) tumors in the Life Span Study cohort of atomic bomb survivors. Cases diagnosed between 1958 and 2009 were ascertained through population-based cancer registries in Hiroshima and Nagasaki. To estimate excess relative risk per Gy (ERR/Gy), we fit rate models using Poisson regression methods. There were 285 CNS tumors (67 gliomas, 107 meningiomas, 49 schwannomas, and 64 other/NOS tumors) among 105,444 individuals with radiation dose estimates to the brain contributing 3.1 million person-years of observation. Based on a simple linear model without effect modification, ERR/Gy was 1.67 (95% confidence interval, CI: 0.12 to 5.26) for glioma, 1.82 (95% CI: 0.51 to 4.30) for meningioma, 1.45 (95% CI: - 0.01 to 4.97) for schwannoma, and 1.40 (95% CI: 0.61 to 2.57) for all CNS tumors as a group. For each tumor type, the dose-response was consistent with linearity and appeared to be stronger among males than among females, particularly for meningioma (P = 0.045). There was also evidence that the ERR/Gy for schwannoma decreased with attained age (P = 0.002). More than 60 years after the bombings, radiation risks for CNS tumors continue to be elevated. Further follow-up is necessary to characterize the lifetime risks of specific CNS tumors following radiation exposure.

Case report: schwannoma arising from the unilateral adrenal area with bilateral hyperaldosteronism

BACKGROUND

We report a rare case of a juxta-adrenal schwannoma that could not be discriminated from an adrenal tumor before surgical resection and was complicated by bilateral hyperaldosteronism. To the best of our knowledge, this is first case in which both a juxta-adrenal schwannoma and hyperaldosteronism co-existed.

CASE PRESENTATION

A 69-year-old male treated for hypertension was found to have a left supra-renal mass (5.8 × 5.2 cm) by abdominal computed tomography. His laboratory data showed that his plasma aldosterone concentration (PAC) was within the normal range, but his plasma renin activity (PRA) was reduced, resulting in an increased aldosterone/renin ratio (ARR). Load tests of captopril or furosemide in the standing position demonstrated autonomous aldosterone secretion and renin suppression. Adrenal venous sampling (AVS) with ACTH stimulation indicated bilateral hypersecretion of aldosterone. A left supra-renal tumor was resected because of the possibility of malignancy and was found to be a benign schwannoma arising from the juxta-adrenal region together with an adrenal gland. The dissected left adrenal gland was morphologically hyperplastic in the zona glomerulosa, but was immunohistochemically negative for CYP11B2 (aldosterone synthase). Multiple CYP11B2-positive adrenocortical micronodules were detected in the adrenal gland, indicating micronodular hyperplasia. Although bilateral aldosteronism was indicated by AVS before the operation, the PRA, PAC and ARR values were within their respective reference ranges after resection of the unilateral tumor, suggesting that the slight increase in hormone secretion from the remaining right-sided lesion could not be detected after resection.

CONCLUSION

A clinical and morphologic diagnosis of juxta-adrenal schwannoma is difficult, particularly in a case of hyperaldosteronism, as shown in this case. These data suggest the complexity and difficulty diagnosing adrenal incidentaloma.

[Neurofibromatosis type 2 in childhood: a clinical characterization]

INTRODUCTION

Neurofibromatosis type 2 (NF2) is a dominantly inherited neuroectodermal syndrome that predispose to the development of tumors of the central and peripheral nervous system. Additional features include eye and skin abnormalities.

CASE REPORT

A 12-year old male with diagnosis of MF2 according to Baser et al and presentation in childhood was included. A comprehensive bibliographic review of evolution of the diagnostic criteria for NF2 in children was performed.

CONCLUSIONS

The pattern of presentation of NF2 in childhood differs from adulthood in many aspects. Ophthalmologic and skin manifestations, and not an auditory dysfunction, are the most common initial symptoms in prepuberal-onset NF2. The most frequent symptoms and signs at presentation are posterior subcapsular cataract, skin manifestations as NF2 plaques and/or peripheral nerve tumors, and neurological dysfunction related to isolated or multiple cranial nerve deficits (other than nerve VIII), brainstem masses or spinal masses. As sensitivity of diagnostic criteria in children is low, those prepuberal patients with congenital or early-onset cataracts and typical skin manifestations of NF2 should be systematically assessed.

Molecular mechanisms promoting the pathogenesis of Schwann cell neoplasms

Neurofibromas, schwannomas and malignant peripheral nerve sheath tumors (MPNSTs) all arise from the Schwann cell lineage. Despite their common origin, these tumor types have distinct pathologies and clinical behaviors; a growing body of evidence indicates that they also arise via distinct pathogenic mechanisms. Identification of the genes that are mutated in genetic diseases characterized by the development of either neurofibromas and MPNSTs [neurofibromatosis type 1 (NF1)] or schwannomas [neurofibromatosis type 2 (NF2), schwannomatosis and Carney complex type 1] has greatly advanced our understanding of these mechanisms. The development of genetically engineered mice with ablation of NF1, NF2, SMARCB1/INI1 or PRKAR1A has confirmed the key role these genes play in peripheral nerve sheath tumorigenesis. Establishing the functions of the NF1, NF2, SMARCB1/INI1 and PRKAR1A gene products has led to the identification of key cytoplasmic signaling pathways promoting Schwann cell neoplasia and identified new therapeutic targets. Analyses of human neoplasms and genetically engineered mouse models have established that interactions with other tumor suppressors such as TP53 and CDKN2A promote neurofibroma-MPNST progression and indicate that intratumoral interactions between neoplastic and non-neoplastic cell types play an essential role in peripheral nerve sheath tumorigenesis. Recent advances have also provided new insights into the identity of the neural crest-derived populations that give rise to different types of peripheral nerve sheath tumors. Based on these findings, we now have an initial outline of the molecular mechanisms driving the pathogenesis of neurofibromas, MPNSTs and schwannomas. However, this improved understanding in turn raises a host of intriguing new questions.

Ile/Ile homozygosity at codon 655 of HER2 in schwannoma

PURPOSE

This study aimed to determine the genetic role of HER2, one of the epidermal growth factor receptor (EGFR) family, in schwannoma. The latter is a neogrowth of myelin-producing Schwann cells in peripheral nerves, inducible by N-nitrosoethylurea in animals with mutation in the neu gene (homologous gene of human HER2 protein).

METHODS

In this study we obtained genomic DNA samples from tissue blocks of schwannoma, initially by xylene treatment and alcohol extraction, followed by use of the DNA extraction kit. Evaluation of this genetic polymorphism in our subjects was conducted by direct nucleotide sequencing or restriction enzyme analyses after PCR work.

RESULTS

There were thirty extracted DNA samples from tissue blocks of schwannoma, and all were Ile/Ile homozygotes after genotype analyses. Two individuals received the leukocyte DNA extraction after peripheral blood sampling, both showing Ile/Ile homozygosity. This study gave the impression of an association of the HER2 polymorphism at codon 655 with tumorigenesis of schwannoma. Although the majority of the Taiwanese showed Ile/Ile homozygosity (about 83%), the present study revealed a 100% carriage rate among the tissue blocks from our subjects with schwannoma.

CONCLUSION

Ile/Ile homozygosity at codon 655 of HER2 in schwannoma may imply some role in tumorigenesis of Ile655Val allele of HER2 in this nerve tumor.

An unusual localization of intraosseus schwannoma: mandibular localization and new pathogenetic prospectives

AIM

The aim of the study is to give an explanation on the Intra-osseous Schwanoma etio-pathogenesis, based on the isto-pathological findings presented by the Authors.

MATERIAL OF STUDY

In a 40 years old patient with pain on the territory innervated by the third right trigeminal branch, OPT showed a like ground-glass area that involved the mandible with the mandibular canal disappearance and dental roots resorption. They removed the lesion with preservation of the vascular-neural beam on which the lesion were extremely attached; the histological examination confirmed the diagnosis of intra-osseous Schwannoma. Immunohistochemically the Schwannoma labelled with antibodies to S-100, Vimentin, Osteopontin and Osteonectin. RESULST: The clinical and radiological follow-up after one year since the surgery, using OPT showed an improvement of bone formation and the disappearance of the pain.

DISCUSSION

Schwannoma rarely presents as an intraosseous mass, comprising less than 1% of all bone tumors with a strong predilection for the mandible. Data like the expression of osteopontin are believed to be distinctive feature of other schwannian cell tumors such as the granular cell tumor. Such data might explain the prevalence of mandibular location among the rare intraosseous schwannomas and might point out that the calcified shwannoma of the skull is similar to an hamartomatous lesion.

[Case of jugular foramen schwannoma associated with tuberous sclerosis]

We report a case of jugular foramen schwannoma associated with tuberous sclerosis. A 28-year-old female with tuberous sclerosis presented to Hikone Municipal Hospital with subacute onset of somnolence, ataxic gait and frequent vomiting. Her tuberous sclerosis was diagnosed at the age of 9, when she developed hydrocephalus caused by subependymal giant cell astrocytoma near the foramen of Monro, which was treated by surgical resection and VP shunt placement followed by radiation and chemotherapy. Brain MR images revealed a 3 cm enhancing mass extending from the left jugular foramen to the cerebellopontine cistern, accompanied by perifocal edema of the brain stem and cerebellar hemisphere. The tumor was partially removed via suboccipital craniotomy and histologically diagnosed as a schwannoma. After surgery her symptoms promptly improved and 4 months later she underwent additional stereotactic radiosurgery. No tumor regrowth has been observed at 94 months. Intracranial schwannoma complicating tuberous sclerosis is very rare. Only one other case has been reported in the literature.

Cervical sympathetic schwannoma with postoperative first bite syndrome

Extracranial schwannomas occurring in the head and neck region may arise from cranial, peripheral or autonomic nerves. Determination of the nerve of origin is not often made until the time of surgery. Schwannomas arising from the cervical sympathetic chain are extremely rare. These interesting tumors along with schwannomas in general and the remaining class of neurogenic tumors are known for their ability to mimic the physical and radiological findings of carotid body tumors. Surgery is the treatment of choice and major complications are infrequent. However, we report a case of cervical sympathetic chain schwannoma with postoperative first bite syndrome.

Radiation induced peripheral nerve tumors: case series and review of the literature

PURPOSE

Radiation induced peripheral nerve tumors (PNT) are a rare but known complication of radiotherapy. The clinical and pathologic features of six cases of post-radiation PNT's are reported here, more than doubling the number of known cases reported in the literature.

METHODS

We reviewed six cases of radiation induced PNT and performed a review of the current literature on radiation induced neurofibromas.

RESULTS

Patient's ranged in age from 18 months to 49 years at the time of their original diagnosis, with radiation doses to the primary tumor ranging from 24 to 40 Gy with post radiation intervals from 10 to 50 years. The majority of PNT's identified were neurofibromas (3) and schwannomas (3). Nuclear atypia, S100 positive staining and mild-moderate cellularity were common pathologic findings.

CONCLUSIONS

There are only a handful of neurofibromas in the 60 cases of PNT's thus far reported. This case series broadens the post-radiation neurofibroma literature. While the pathology of PNT induced transformation is still poorly understood, experiments and pathology are congruent on the possibility of malignant transformation, especially for the "atypical neurofibroma". On the clinical level, this case series lends its support to some, but not all, of the risk factors thought to predispose to the formation of radiation induced neurofibromas. Though rare, the complication of radiation-induced neurofibroma cannot be ignored, especially with the increasing use of focused radiosurgical techniques.

Uptake of 4-borono-2-[18F]fluoro-L-phenylalanine in sporadic and neurofibromatosis 2-related schwannoma and meningioma studied with PET

PURPOSE

Meningiomas and schwannomas associated with neurofibromatosis 2 (NF2) are difficult to control by microsurgery and stereotactic radiotherapy alone. Boron neutron capture therapy (BNCT) is a chemically targeted form of radiotherapy requiring increased concentration of boron-10 in tumour tissue. PET with the boron carrier 4-borono-2-[(18)F]fluoro-L-phenylalanine ([(18)F]FBPA) allows investigation of whether 4-borono-L-phenylalanine (BPA) concentrates in NF2 tumours, which would make BNCT feasible.

METHODS

We studied dynamic uptake of [(18)F]FBPA in intracranial meningiomas (n=4) and schwannomas (n=6) of five sporadic and five NF2 patients. Tracer input function and cerebral blood volume were measured. [(18)F]FBPA uptake in tumour and brain was assessed with a three-compartmental model and graphical analysis. These, together with standardised uptake values (SUVs), were used to define tumour-to-brain [(18)F]FBPA tissue activity gradients.

RESULTS

Model fits with three parameters K (1) (transport), k (2) (reverse transport) and k (3) (intracellular metabolism) were found to best illustrate [(18)F]FBPA uptake kinetics. Maximum SUV was two- to fourfold higher in tumour as compared with normal brain and independent of NF2 status. The increased uptake was due to higher transport of [(18)F]FBPA in tumour. In multiple-time graphical analysis (MTGA, Gjedde-Patlak plot) the tumour-to-brain [(18)F]FBPA influx constant (K (i) -MTGA) ratios varied between 1.8 and 5.4 in NF2-associated tumours while in sporadic tumours the ratio was 1-1.4.

CONCLUSION

[(18)F]FBPA PET offers a viable means to evaluate BPA uptake in meningiomas and schwannomas in NF2. Based on our results on tumour uptake of [(18)F]FBPA, some of these benign neoplasms may be amenable to BNCT.

The enigmatic origin of subfrontal schwannomas: report of a case without hyposmia

Subfrontal schwannomas are rare intracranial tumors. Most of them are associated with hyposmia/anosmia. The source of origin of these tumors is still incompletely understood. We report a 23-year-old male who presented with recurrent focal motor seizures, but had no hyposmia. The tumor was completely removed by a subfrontal approach. Relevant literature has been reviewed.

Large Presacral Schwannoma after Radical Prostatectomy

A 56-year-old man presented with long-standing, mild urinary frequency 6 years after radical prostatectomy. Pathologic assessment showed presence of organ confined prostate cancer (pT2a), Gleason 6 (3+3). Since the time of surgery, PSA level was undetectable and the patient remained without evidence of recurrent disease. However, digital rectal examination revealed the presence of a very large mass palpable on the anterior rectal wall. Therefore, the patient underwent abdominal/pelvic MRI which demonstrated presence of a solid, well-circumscribed pelvic mass extending from the level of the sacrum posteriorly to the anterior abdominal wall. Histologic examination of percutaneous biopsy of the mass was suggestive of schwannoma. The patient underwent laparotomic excision of the mass, which was confirmed to be a schwannoma, with its characteristic slender spill cells and elongate nuclei. No intra-operative complication was reported. The patient has no evidence of recurrence with complete resolution of urinary symptom one year after surgery.

[Endoscopic removal of sinonasal tumors]

OBJECTIVES

To evaluate the efficacy of endoscopic surgery for sinonasal tumors.

PATIENTS AND METHODS

Clinical records of 20 patients (10 males, 10 females; mean age 34; range 12 to 63 years) who underwent endoscopic tumor resection with diagnosis of sinonasal tumor between January 1998 and August 2004 were retrospectively reviewed. Patients who were operated by transnasal endoscopic surgery or by combined (endoscopic or external) surgical methods were included in the study. Patients were reviewed for age, sex, pathologic diagnosis and tumor location, surgical techniques, need for additional surgery, complications, recurrence, and follow-up period.

RESULTS

There were five osteomas, one fibrous dysplasia, one ossifying fibroma, seven inverted papillomas, one oncocytic papilloma, three angiofibromas, one schwannoma, and one esthesioneuroblastoma. The patients follow-up period ranged between 6 months and 6 years (mean 26 months). The fibrous dysplasia involving the posterior ethmoid sinuses was subtotally resected due to its close proximity to the optic nerve. One inverted papilloma of the maxillary sinus was resected by a combined endoscopic and Caldwell-Luc approach. A combined endoscopic intranasal and external frontoethmoidectomy approach was performed for the removal of frontal sinus schwannoma. Recurrence was observed in one of the inverted papilloma cases. Total removal of the tumors was achieved in all other cases without any complications or recurrences.

CONCLUSION

Low recurrence rates in our series showed that endoscopic resection of nasal-paranasal sinus tumors in selected cases, may be an appropriate method as solely or in combined with other surgical techniques for experienced surgeons.

[Benign schwannoma: a case report about a uncommon localisation]

Schwannoma is a benign slow growing nerve sheath tumor which generally originates from cranial or spinal nerve roots. Peripheral nerve localisations are scarce. We report the case of a 76-year man who presented with a laterosternal chest wall mass located in the fourth intercostal space. Diagnosis of intercostal benign schwannoma was suggested by medical imaging and confirmed histologicolly upon surgical removal. Chest wall solitary schwannoma is exceptional. Our case is still more interesting by its peripheral localisation and late occurence following a chest trauma.

A very large Schwannoma originating from the median nerve in carpal tunnel

Schwannomas are common benign nerve tumors occurring in the peripheral nerves. A very large schwannoma of more than 5 years duration, originating from the median nerve in the carpal tunnel in a 38-year-old woman, is reported. There was a painful mass, 60 mm in length and 42 mm in diameter, on the palm without signs of sensory disturbance or atrophy on the thenar muscles. Surgical removal was performed under high-power magnification by separating the sensory and motor fascicles from the tumor. Histological examination resulted in a Schwannoma. At 4-year follow-up, the patient was asymptomatic with excellent relief of symptoms. The tumor did not recur. Although cases have been reported in the literature, this is one of the largest ever described without any neurologic deficit.

Second tumors after radiosurgery: tip of the iceberg or a bump in the road?

OBJECTIVE

Radiosurgery-associated second tumors have been reported in four isolated patients during the past 2 years. In our own experience, we are aware of two additional patients. The purpose of this report is to call attention to this potentially emerging problem.

METHODS

A review of the English-language literature concerning patients with radiosurgery-associated second tumors was performed. In addition, we report on two patients in our own practice who were treated in the past year.

RESULTS

Four patients were found in the literature, and two additional patients were seen by the authors. Malignant tumors occurred as early as 6 years after radiosurgery. The pathological findings in three of these four malignant tumors were glioblastoma multiforme. Benign tumors developed between 16 and 19 years later. Tumors developed both within the full-dose prescription volume and in the lower-dose periphery. Of interest, three of the six patients experienced complications of the radiosurgery treatment before developing second tumors.

CONCLUSION

Although patients will increasingly be reported with second tumors after radiosurgery in the future, the overall incidence seems quite low and should not alter current radiosurgical practice. However, continual surveillance of treated patients should be considered.

Risk factors for pediatric human immunodeficiency virus-related malignancy

CONTEXT

Although cancers occur with increased frequency in children with human immunodeficiency virus (HIV) infection, the specific clinical, immunological, and viral risk factors for malignancy have not been identified.

OBJECTIVE

To identify risk factors for malignancy among HIV-infected children.

DESIGN, SETTING, AND PATIENTS

A multicenter case-control study of children with HIV at 26 institutions participating in the Pediatric Oncology Group. Forty-three case patients with a new malignancy and 74 control patients without a malignancy were matched based on the duration of their infection. Patients were enrolled between January 1992 and July 1998.

MAIN OUTCOME MEASURES

Clinical and laboratory factors assessed as putative risk factors included demographic characteristics, HIV characteristics, prior antiretroviral treatment, and CD4 cell count. Coviral infections with Epstein-Barr virus (EBV), cytomegalovirus, and human herpesvirus 6 were assessed by semiquantitative polymerase chain reaction assays and serological testing.

RESULTS

Case malignancy diagnoses included 28 non-Hodgkin lymphoma, 4 B-cell acute lymphoblastic leukemia, 1 Hodgkin disease, 8 leiomyosarcoma, 1 hepatoblastoma, and 1 schwannoma. Epstein-Barr virus viral load of more than 50 viral genome copies per 105 peripheral blood mononuclear cells was strongly associated with cancer risk but only for children with CD4 cell counts of at least 200/ microL (odds ratio [OR], 11.33; 95% confidence interval [CI], 2.09-65.66, P<.001). High EBV viral load was not associated with cancer for children with CD4 cell counts of less than 200/ microL (OR, 1.12; 95% CI, 0.13-9.62; P =.99). Zidovudine antiretroviral therapy did not confer a significant protective effect for either the high (OR, 0.81; 95% CI, 0.22-3.09; P =.77) or the low CD4 cell count groups (OR, 0.27; 95% CI, 0.04-1.46; P =.16). The route of HIV infection was not associated with increased cancer risk.

CONCLUSIONS

Route of infection, demographic characteristics, and zidovudine use were not associated with the development of malignancy in HIV-infected children. High viral burden with EBV was associated with the development of malignancy in HIV-infected children although the effect was modified by CD4 cell count. The pathogenesis of HIV-related pediatric malignancies remains unclear and other contributing risk factors can be elucidated only through further study.

Expression of Ki-67 antigen and vascular endothelial growth factor in sporadic and neurofibromatosis type 2-associated schwannomas

Neurofibromatosis type 2 (NF2) is a formidable disease with considerable morbidity. Among tumors associated with NF2, schwannomas are the most difficult to treat because they are multiple and tend to recur. Vascular endothelial growth factor (VEGF) has been reported to act as a survival factor for Schwann cells. We, therefore, investigated VEGF expression in NF2-associated and sporadic schwannomas. We also evaluated the proliferative potential of these tumors by Ki-67 staining (MIB-1 labeling index) and microvascular density by CD34 staining. Immunohistochemistry was performed in 8 schwannomas from 6 NF2 patients, 2 schwannomas from 2 probable NF2 patients and 10 sporadic schwannomas. VEGF immunostaining was present in most schwannomas: all sporadic schwannomas and 8 of 10 schwannomas from NF2 or probable NF2 patients (NF2 group). No difference was evident in VEGF staining between the 2 groups. MIB-1 labeling index was significantly higher in the NF2 group (3.8 +/- 1.7) than the sporadic group (2.0 +/- 1.0, p < 0.01). Microvascular density was higher in the NF2 group (12.9 +/- 6.0) than the sporadic group (9.4 +/- 3.5), but not significantly (p = 0.06). Although VEGF alone cannot explain the higher proliferative potential in NF2-associated schwannomas, VEGF could be a factor influencing the proliferative potential of schwannomas.

Tumors of the nervous system and pituitary gland associated with atomic bomb radiation exposure

BACKGROUND

The risk of developing nervous system tumors following exposure to ionizing radiation is not well quantified. We characterized the incidence of nervous system tumors among atomic bomb survivors as a function of radiation dose.

METHODS

Tumors of the nervous system and pituitary gland diagnosed between 1958 and 1995 among 80 160 atomic bomb survivors were ascertained using the Hiroshima and Nagasaki tumor registries, medical records, and death certificates. Pathologists reviewed slides and medical records to provide histologic diagnoses. Poisson regression analyses were used to characterize radiation effects on tumor incidence, which are expressed as excess relative risk per sievert (ERR(Sv)). All statistical tests were two-sided.

RESULTS

A statistically significant dose-related excess of nervous system tumors was observed in the cohort (ERR(Sv) = 1.2, 95% confidence interval [CI] = 0.6 to 2.1). The highest ERR(Sv) was seen for schwannoma (4.5, 95% CI = 1.9 to 9.2). The risk for all other nervous system tumors as a group is also statistically significantly elevated (ERR(Sv) = 0.6, 95% CI = 0.1 to 1.3). Risk increases, although not statistically significant, were seen for meningiomas (ERR(Sv) = 0.6, 95% CI = -0.01 to 1.8), gliomas (ERR(Sv) = 0.6, 95% CI = -0.2 to 2.0), other nervous system tumors (ERR(Sv) = 0.5, 95% CI = <-0.2 to 2.2), and pituitary tumors (ERR(Sv) = 1.0, 95% CI = <-0.2 to 3.5). The dose-response relationships were linear. For nervous system tumors other than schwannoma, excess risks were higher for men than for women and for those exposed during childhood than for those exposed during adulthood.

CONCLUSIONS

A statistically significant dose response was observed for all nervous system tumors combined and for schwannoma considered separately, indicating that exposure to even moderate doses (i.e., <1 Sv) of radiation is associated with an elevated incidence of nervous system tumors.

Malignant triton tumor of the supraclavicular region arising after radiotherapy

Malignant triton tumor (MTT) is a relatively rare, aggressive tumor comprised of both malignant schwannoma cells and malignant rhabdomyoblasts. Only three cases of MTT which arose after radiation therapy were reported in the literature. We presented an additional case of MTT arising after radiotherapy and discussed its clinical and pathological characteristics.

Mouse models of neurofibromatosis 1 and 2

The neurofibromatoses represent two of the most common inherited tumor predisposition syndromes affecting the nervous system. Individuals with neurofibromatosis 1 (NF1) are prone to the development of astrocytomas and peripheral nerve sheath tumors whereas those affected with neurofibromatosis 2 (NF2) develop schwannomas and meningiomas. The development of traditional homozygous knockout mice has provided insights into the roles of the NF1 and NF2 genes during development and in differentiation, but has been less instructive regarding the contribution of NF1 and NF2 dysfunction to the pathogenesis of specific benign and malignant tumors. Recent progress employing novel mouse targeting strategies has begun to illuminate the roles of the NF1 and NF2 gene products in the molecular pathogenesis of NF-associated tumors.

Hyperprolactinaemia and prolactin binding in benign intracranial tumours

BACKGROUND

Meningiomas have been found to have receptors for several hormones, such as oestrogen, progesterone, somatostatin, dopamine and recently also for prolactin.

METHODS

To investigate any possible role of prolactin in the growth of those tumours we detected the presence of prolactin-receptors (PRL-R) in 22 meningiomas and we correlated these data with PRL serum levels in patients before surgery. We also studied 13 patients with schwannomas and 7 with other cerebral tumours (4 glioblastomas, 2 ependymomas and 1 astrocytoma).

RESULTS

Increased prolactin binding was present in 10 (45.4 percent;) meningiomas, 9 (69.2 percent;) schwannomas and in the patient with astrocytoma. The presence of high PRL levels was present in 6 (27.2 percent;) patients with meningiomas, 8 (61.5 percent;) with schwannomas and in 3 (42.8 percent;) with other tumours. No direct correlation was present between serum PRL levels and PRL binding in all groups.

CONCLUSIONS

In conclusion we confirmed the presence of PRL receptors in patients with meningiomas and we have also shown the presence of PRL receptors also in schwannomas. Moreover increased serum PRL were shown in some patients with different tumours of nervous tissue before surgery. Our data could suggest that PRL might have a role in the growth of meningiomas and schwannomas.

The effects of 860 MHz radiofrequency radiation on the induction or promotion of brain tumors and other neoplasms in rats

Sprague-Dawley rats were irradiated with a continuous- wave (CW) or a pulsed-wave (P) radiofrequency (RF) for 6 h/day, 5 days/week from 2 up to 24 months of age. The RFs emanated from dipole antennas (1 W average output) 2.0 +/- 0.5 cm from the tip of each rat's nose. The RFs had an 860 MHz frequency, and the specific absorption rate was 1.0 W/ kg averaged over the brain. Fifteen groups of 60 rats (900 total) were formed from offspring of females injected i.v. with 0 (groups 1, 2, 9, 10, 13), 2.5 (groups 5, 6, 7, 8, 11, 12, 14) or 10 mg/kg (groups 3, 4, 15) ethylnitrosourea (ENU) to induce brain tumors. Groups 1, 3, 5 and 7 received the PRF, and groups 9 and 11 the CWRF; groups 2, 4, 6, 8, 10 and 12 were sham-irradiated, and groups 13-15 were cage controls. All rats but 2, totaling 898, were necropsied, and major tissues were studied histopathologically. There was no statistically significant evidence that the PRF or CWRF induced neoplasia in any tissues. Additionally, there was no significant evidence of promotion of cranial or spinal nerve or spinal cord tumors. The PRF or CWRF had no statistically significant effect on the number, volume, location, multiplicity, histological type, malignancy or fatality of brain tumors. There was a trend for the group that received a high dose of ENU and was exposed to the PRF to develop fatal brain tumors at a higher rate than its sham group; however, the result was not significant using the log-rank test (P = 0.14, 2-tailed). No statistically significant differences were related to the PRF or CWRF compared to controls in the low- or zero-dose groups regarding tumors of any kind.

Cutaneous malignant epithelioid neoplasms

In summary, cutaneous malignancies with an epithelioid appearance form a diverse group of neoplasms that may be difficult to diagnose by utilizing routine microscopy alone. Cutaneous malignancies, including malignant melanoma and metastatic carcinoma, certain benign neoplasms such as mixed tumor of the skin and angiolymphoid hyperplasia with eosinophils (epithelioid hemangioma), and infectious conditions such as bacillary (epithelioid) angiomatosis can be considered in this differential. However, through recognition of the characteristic histologic, immunocytochemical, and ultrastructural findings outlined above, definitive diagnosis of these challenging neoplasms is usually possible.

Malignancy in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) represents a major risk factor for development of malignancy, particularly malignant peripheral nerve sheath tumors (MPNST), optic gliomas, other gliomas, and leukemias. The oncologist will see NF1 patients referred for treatment of malignancy, and should be alert to the possibility of undiagnosed NF1 among patients with cancer. Brain tumors tend to have a more indolent course in NF1 than in the general population, and hence are best managed conservatively. MPNST, in contrast, do not respond to standard chemotherapy or radiation therapy. The most effective treatment of MPNST appears to be early diagnosis and surgery, but early diagnosis is hampered by frequent occurrence within preexisting large tumors, making new growth or change difficult to detect. New insights into pathogenesis now offer hope of development of specific methods of treatment with reduced toxicity and more precise molecular targeting. There is an urgent need, however, to develop methods to measure tumor growth and monitor outcomes, develop preclinical drug screening systems, and further explore the pathogenesis of the disorder to determine whether mechanisms other than Ras regulation may be important in pathogenesis.

Tumors in long-term rat studies associated with microchip animal identification devices

Tumors surrounding implanted microchip animal identification devices were noted in two separate chronic toxicity/oncogenicity studies using F344 rats. The tumors occurred at a low incidence rate (approximately 1 percent), but did result in the early sacrifice of most affected animals, due to tumor size and occasional metastases. No sex-related trends were noted. All tumors occurred during the second year of the studies, were located in the subcutaneous dorsal thoracic area (the site of microchip implantation) and contained embedded microchip devices. All were mesenchymal in origin and consisted of the following types, listed in order of frequency: malignant schwannoma, fibrosarcoma, anaplastic sarcoma, and histiocytic sarcoma. The following diagnostic techniques were employed: light microscopy, scanning electron microscopy, and immunohistochemistry. The mechanism of carcinogenicity appeared to be that of foreign-body induced tumorigenesis.

Intracanalicular schwannoma of the facial nerve: a manifestation of neurofibromatosis type 2

Primary facial nerve tumors, which are relatively uncommon, can present a diagnostic dilemma based on their location and variable pattern of symptoms. Of primary cranial nerve tumors, schwannomas of the facial nerve rank third in frequency after those of the eighth and fifth cranial nerves. We report an illustrative case of an intracanalicular schwannoma associated with several central nervous system tumors, consistent with neurofibromatosis type 2. Initially assumed to be an eighth cranial nerve tumor, the schwannoma was found intraoperatively to arise from the facial nerve. Early diagnosis and treatment enabled excision of the tumor without sacrifice of the facial nerve. Facial nerve schwannomas can resemble acoustic schwannomas in their clinical presentation. Only a heightened level of clinical vigilance will point to the correct diagnosis and result in an optimal therapeutic outcome for patients with these rare tumors.

Evaluation of the potential promoting effect of 60 Hz magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in female F344 rats

The present study investigated the possible effect of 60 Hz magnetic fields (MFs) as promoters of neurogenic tumors initiated transplacentally by a chemical carcinogen, N-ethyl-N-nitrosourea (ENU). In a preliminary study, 5 mg of ENU was shown to induce 30 to 40% neurogenic tumors in F344 rats offspring after 420 days of observation. In the present study, 400 female rats were divided into eight different groups (50 animals/group) and exposed in utero (on day 18 of gestation) to a single intravenous dose of either Saline (Group I), or ENU, 5 mg/kg (Group II to VIII). Dams in group II were given no further treatment while dams in Groups III to VII were exposed to 5 different intensities of MFs forty eight hours later. Animals in group III were sham exposed (<0.02 microT) while groups IV to VII were exposed to 2, 20, 200, and 2000 microT, respectively. Dams in Group VIII were injected intraperitoneally with 12-O-tetradecanoylphrobol-13-acetate (TPA; 10 micrograms/kg) from day 19 until delivery, and then their female offspring continued to be injected every 15 days, starting at day 14 after birth until sacrifice (positive controls). Accordingly, this study included three different types of controls: Internal controls (Groups II and III) and positive control (Group VIII). Body weight, mortality and clinical observations were evaluated in all groups of animals during in-life exposure. Necropsy was performed on all exposed and control animals that died, were found moribund or sacrificed at termination of the study. Histopathological evaluation was done for all brains, spinal cords, cranial nerves, major organs (lungs, liver, spleen, kidneys, pituitary, thyroid and adrenals) and all gross lesions observed during necropsy. All clinical observations and pathological evaluations were conducted under "blinded" conditions. The findings from this ENU/MFs promotion study clearly demonstrate that, under our defined experimental conditions, exposure to 60 Hz linear (single axis) sinusoidal, continuous wave MFs had no effect on the survival of female F344 rats or on the number of animals bearing neurogenic tumors. These results suggest that MFs have no promoting effect on neurogenic tumors in the female F344 rats exposed transplacentally to ENU.

Schwann cell hyperplasia and tumors in transgenic mice expressing a naturally occurring mutant NF2 protein

Specific mutations in some tumor suppressor genes such as p53 can act in a dominant fashion. We tested whether this mechanism may also apply for the neurofibromatosis type-2 gene (NF2) which, when mutated, leads to schwannoma development. Transgenic mice were generated that express, in Schwann cells, mutant NF2 proteins prototypic of natural mutants observed in humans. Mice expressing a NF2 protein with an interstitial deletion in the amino-terminal domain showed high prevalence of Schwann cell-derived tumors and Schwann cell hyperplasia, whereas those expressing a carboxy-terminally truncated protein were normal. Our results indicate that a subset of mutant NF2 alleles observed in patients may encode products with dominant properties when overexpressed in specific cell lineages.

Higher incidence of malignant neoplasms after heart transplantation for treatment of chronic Chagas' heart disease

BACKGROUND

Heart transplantation is a new therapeutic procedure to treat heart failure resulting from Chagas' disease. Experimental studies have demonstrated neoplastic effects of benznidazole, which is used for treatment of Trypanosoma cruzi infection. We compared the incidence and characteristics of neoplasia after heart transplantation for treatment of chronic Chagas' disease with those of other diseases.

METHODS

Sixteen patients with Chagas' disease and 75 patients with other diseases underwent heart transplantation. Benznidazole was administered to 14 patients with Chagas's disease either for prophylaxis (4 patients) or for treatment of Chagas' disease reactivation (10 patients).

RESULTS

The survival rate of patients in the nonchagasic group was 90% at 1 year and 82.4% at 2 years, and the survival rate in the chagasic group was 63% at 1 year and 57% at 2 years. Six of 16 patients (37.5%) with Chagas' disease had malignant tumors after a mean follow-up time of 25.3+/-2.1 months in contrast to 2 of 75 patients (2.7%) in the nonchagasic group after 34.6+/-3.6 months of follow-up. In the chagasic group, lymphoproliferative disorder was diagnosed in three patients, Kaposi's sarcoma in two, and squamous cell carcinoma in one patient. Reactivation of T. cruzi infection was diagnosed in all patients who had lymphoproliferative disorder. One patient without Chagas' disease had lymphoproliferative disorder in the lung, and another had malignant schwannoma affecting the skin.

CONCLUSIONS

We found a higher incidence of malignant neoplasia after heart transplantation for treatment of chronic Chagas' disease. It is likely that the neoplasia is the result of chronic infection with an immunomodulator protozoan, immunosuppression, reactivation of the T. cruzi infection, or the toxicity of therapeutic intervention with benznidazole.

Incidence of intracranial tumors following hospitalization for head injuries (Denmark)

The incidence of brain and other intracranial tumors following head trauma was evaluated in a cohort of 228,055 Danish residents hospitalized because of concussion, fractured skull, or other head injury between 1977 and 1992 and followed for an average of eight years (maximum, 17 years). Traffic accidents, falls, and sports-related incidents were the usual causes of the injury. Malignant and benign neoplasms were identified by linking the study roster with records of the Danish Cancer Registry for the years 1977 to 1993. This approach precludes differential reporting of injuries by study participants as an explanation for any associations seen. Intracranial tumors of the nervous system occurred more often than expected based on incidence rates for the Danish population; however, most of the excess occurred during the first year after the injury and likely was due to the detection of tumors that were present before the injury occurred. Excluding the first year of follow-up, the standardized incidence ratio (SIR) was 1.15 (95 percent confidence interval [CI] = 0.99-1.32). The same general temporal pattern was seen for the major subtypes of brain tumor as for all types combined. SIRs after the first year were 1.0 for glioma (CI = 0.8-1.2), 1.2 for meningioma (CI = 0.8-1.7), and 0.8 for neurilemmoma (CI = 0.4-1.7). However, hemangioblastoma and hemangioma were more frequent than expected, based on 15 cases (SIR = 2.6, CI = 1.4-4.2). Results indicate that head trauma causes, at most, a small increase in the overall risk of brain tumors during the ensuing 15 years; however, a possible association with intracranial vascular tumors warrants further evaluation.

[Neurofibromatosis with abdominal and severe central nervous system complications]

A young male patient suffered in cutaneous neurofibromatosis was followed during four years. He developed tissue proliferations of various histological structures manifested in the skin, central nervous system and different splanchnic organs. The classification criteria of neurofibromatosis as well as the diagnostic and therapeutic recommendations are discussed.

Multiple schwannomas and meningiomas associated with irradiation in childhood

OBJECTIVE

To determine the pattern of neural tumors (schwannomas, vestibular schwannomas [acoustic neuromas], and meningiomas) that developed in 3013 people who received radiation treatment with x-ray beam therapy for benign conditions of the head and neck area before their 16th birthday.

METHODS

The surgical and pathology reports and pathology slides were reviewed for all neural tumors in the cohort. Patients with more than 1 neural tumor were compared with those with 1 neural tumor and those with no neural tumors.

RESULTS

There were 7 patients with multiple neural tumors and 63 with single neural tumors. The distribution of tumors in these 2 groups differed. The group with multiple tumors had more spinal nerve root schwannomas, while the group with single tumors had more cranial nerve schwannomas. Six of the 7 patients did not meet the diagnostic criteria for neurofibromatosis type 2.

CONCLUSIONS

Our findings suggest that host factors that increase susceptibility to radiation may be involved in the development of the multiple neural tumors. Clinically, patients with multiple neural tumors who do not meet the diagnostic criteria for neurofibromatosis type 2 should be questioned about radiation exposure. If exposure is confirmed, then screening for other radiation-related tumors should be initiated.

Malignant schwannoma in a burn scar

The malignant potential of a burn scar is well recognized. Epidermal malignancies predominate and sarcomas are a rare finding. The first case of a malignant schwannoma developing in a burn scar is reported, and the management discussed.

Radiation induced malignant schwannoma arising in a neurofibroma

Radiation induced sarcomas offer diagnostic and therapeutic challenges. The authors report an unusual case of radiation induced sarcoma arising 9 years after radiation therapy for chordoma. The location of this mass in the retroperitoneum and its intimate involvement with the spine raised difficult management issues. After limited resection was performed, consistent with the intraoperative diagnosis of a benign neurofibroma, foci of malignant transformation were found in areas of the specimen remote from the biopsy site. This complicated management of the sarcoma. The possibility of occult malignancy should be considered when evaluating tumors arising in a previously irradiated field. Thorough sampling at the time of biopsy is required to evaluate such lesions, particularly peripheral nerve sheath tumors.

[von Recklinghausen's disease complicated by macroglobulinemia, malignant schwannoma and pheochromocytoma]

We reported a case of von Recklinghausen's disease complicated by macroglobulinemia, malignant Schwannoma and pheochromocytoma. A 43-year-old male patient who was diagnosed as von Recklinghausen's disease developed abdominal masses at 5 years after the adrenalectomy for pheochromocytoma. Computed tomography showed multiple heterogeneous tumors in abdominal cavity. Histological examination of resected tumor was compatible with malignant Schwannoma. At the same time, peripheral blood and bone marrow smears showed a large number of plasmacytoid lymphocytes. Immunoelectrophoresis revealed M-protein of IgM, kappa type. He was also diagnosed of coexistence with macroglobulinemia. The chemotherapeutic protocols used were not effective against both malignant Schwannoma and macroglobulinemia. The present case is a rare case of von Recklinghausen's disease associated with triple neoplasms.

Hypomyelinating peripheral neuropathies and schwannomas in transgenic mice expressing SV40 T-antigen

We have prepared transgenic mice carrying a temperature-sensitive mutant of the SV40 oncogene (tsA-1609) under the control of 5' flanking sequences from the Schwann cell-specific P0 gene. Four of six founder mice showed moderate to severe hypomyelination in peripheral nerves of tail biopsies, with only rare myelinated fibers. Offspring were obtained from three of these founders. Northern blot and immunohistochemical analyses showed that expression of T-antigen was restricted to the PNS. Mice expressing the highest levels of T-antigen exhibited the most severe hypomyelination. Mice expressing lower levels developed transient mild hypomyelination, but after long latencies developed sporadic schwannomas. An immortalized cell line exhibiting properties of Schwann cells at an arrested stage of differentiation, termed "SCT-1," was derived from one of these tumors.

[Thoracic meningocele and neurinoma complicating von Recklinghausen disease. Value of imaging in therapeutic management. Apropos of 2 cases]

We report two cases neurogen tumors (neurinoma and méningocèle) in neurofibromatosis. The progress of imaging techniques, with the use of CT and MRI, is helpful for evaluating these patients, distinguish malignant from benign neoplasm and screening the therapeutic indication.

[The role of dysembryogenesis in the development of spinal cord tumors]

Experience of treatment of 36 patients with extramedullary spinal cord tumors is summarized. Pigmented macules, papillomas or the spinous processes painfulness while irritation were determined on skin in accordance to tumor localization in the innervation zone of one or two segments.

[A case of neurinoma combined with testicular feminization syndrome]

A 23-year-old female was admitted to our hospital because of a mediastinal tumor. She complained of primary amenorrhea, and abdominal echosonography was therefore performed, revealing the absence of a uterus. Chromosome analysis revealed a 46 XY genotype, indicating the patient to be a male, not a female. Left renal venography demonstrated residual blood vessels originating in the Mullerian ducts. Thoracotomy and laparotomy were performed, and the mediastinal tumor and bilateral testes were resected. Postoperative pathology revealed that the mediastinal tumor was a neurinoma. There was no spermatogenesis, but hyperplasia of Sertoli cells in the testes was seen. Neither the neurinoma nor the testes were malignant. Bioassay of the testes showed no androgen receptors, leading to the diagnosis of testicular feminization syndrome with the complete form of androgen insensitivity. There have been many reports of an association between testicular feminization syndrome and malignant tumors of the testes, but few reports of an association between testicular feminization syndrome and benign tumors such as neurinoma. Accordingly, the present case was considered to be unusual and worth reporting.