Arielle Lellouch-Tubiana

Congenital lumbosacral lipomas

Abstract Congenital lumbosacral lipomas can be responsible for progressive defects. The general feeling is that tethering of roots, filum, or cord probably explains this evolution, and that untethering of these structures could prevent late deterioration. Like the vast majority of neurosurgeons, we too have routinely and systematically operated on lumbosacral lipomas, even in the absence of neurological deficits. This policy stemmed from our belief that spontaneous neurological deterioration was frequent, recovery from preoperative deficits rare, and surgery both efficient and benign in nature. After 22 years of experience, we felt that it was necessary to review our series of 291 lipomas (38 lipomas of the filum and 253 of the conus) operated on from 1972 to 1994. To reassess the value of pro-phylactic surgery, we attempted an accurate evaluation of (1) the risk of pathology, (2) the risks involved in surgery, (3) the postoperative outcome with respect to preoperative deficits, and (4) the postoperative outcome in asymptomatic patients at 1 year and at maximum follow-up. Special attention was paid to 93 patients whose postoperative follow-up was more than 5 years (average 8.7, median 8, range 5–23 years). Of these 93 patients, 39 were asymptomatic preoperatively (7 with lipoma of the filum and 32 with lipoma of the conus). Lipomas of the filum and of the conus are entirely different lesions and were studied separately. In 6 cases prenatal diagnosis had been possible. The mean age at surgery was 6.4 years. Low back skin stigmata were present in 89.4% of cases. Preoperative neurological deficits existed in 57% of the patients and were congenital in 22%. Clinical signs and symptoms recorded were pain in 13.3% of the patients and/or neurological deficits affecting sphincter (52%), motor (27.6%) and sensory (22.4%) functions. Deficits were progressive in 22.4% of cases, slowly progressive in 58.8% of these and rapidly progressive in the remaining 41.2%. In 36 patients (13.2%) the lipomas were seen to grow either subcutaneously or intraspinally. Among these patients, 21 were infants, 2 were obese adolescents, and 10 were pregnant women. The metabolism of the fat within the lipomas was studied in 11 patients and found to be similar to that at other sites. Lipomas were associated with various other malformations, either intra- or extraspinal. These associated anomalies were rare in the case of lipomatous filum (5.2%) but frequent with lipomas of the conus, except for intracranial malformations (3.6%). Therapeutic objectives were spinal cord untethering and decompression, sparing of functional neural tissue and prevention of retethering. Procedures used to achieve these goals were subtotal removal of the lipoma, intraoperative monitoring, duroplasty, and sometimes closure of the placode. Histologically, lipomas consisted of normal mature fat. However, 77% of them also included a wide variety of other tissues, originating from ectoderm, mesoderm, or entoderm. This indicates that lipomas are either simple or complex teratomas. The results of the study are as follows. (1) Surgery was easy and safe when performed for treatment of lipomas of the filum (no complications), but difficult and hazardous in the case of lipomas of the conus (20% local, 3.9% neurological complications). (2) All types of deficit could be improved by surgery, which was beneficial in all cases of lipoma of the filum and 50% of cases of lipoma of the conus. (3) In asymptomatic patients long-term surgical results depended on the anatomical type of the lipoma. They were excellent in lipomas of the filum. In lipomas of the conus they were good in the short term but eroded with time. At more than 5 years of follow-up only 53.1% of the patients were still free of symptoms. (4) Reoperations were performed in 16 patients (5.5%), 5 (31.2%) of whom improved postoperatively, while in 7 (43.7%) progression stopped, in 3 (18.7%) deterioration continued and in 1 (6.2%) the condition was worse after surgery. (5) The natural history of the malformation, that is to say the risk of spontaneous aggravation, has only been evaluated in hospital in-patients, so that the true level of risk remains unknown. This means we cannot interpret the actuarial curve following surgery for asymptomatic lipoma of the conus. In conclusion, there are two different types of lipoma: lipoma of the filum, for which surgery is harmless and beneficial in both the short and the long term, and lipoma of the conus, for which surgery involves considerable risks and is of questionable benefit in the long term. This raises the question as to whether prophylactic surgery is indicated for patients with asymptomatic lipomas of the conus, and whether the outcome is any better than it would be if the lipoma were left to take its natural course. The lack of basic information remains a stumbling block to management of these patients. Until this is remedied, we are unable to recommend prophylactic surgery in patients with asymptomatic lipomas of the conus.

Beta-catenin status in paediatric medulloblastomas: correlation of immunohistochemical expression with mutational status, genetic profiles, and clinical characteristics†

Medulloblastoma is the most frequent malignant paediatric brain tumour. The activation of the Wnt/β‐catenin pathway occurs in 10‐15% of medulloblastomas and has been recently described as a marker for favourable patient outcome. We report a series of 72 paediatric medulloblastomas evaluated for β‐catenin protein expression, CTNNB1 mutations, and comparative genomic hybridization. Gene expression profiles were also available in a subset of 40 cases. Immunostaining of β‐catenin showed extensive nuclear staining (>50% of the tumour cells) in six cases and focal nuclear staining (<10% of cells) in three cases. The other cases either exhibited a signal strictly limited to the cytoplasm (58 cases) or were negative (five cases). CTNNB1 mutations were detected in all β‐catenin extensively nucleopositive cases. The expression profiles of these cases documented strong activation of the Wnt/β‐catenin pathway. Remarkably, five out of these six tumours showed a complete loss of chromosome 6. In contrast, cases with focal nuclear β‐catenin staining, as well as tumours with negative or cytoplasmic staining, never demonstrated CTNNB1 mutation, Wnt/β‐catenin pathway activation or chromosome 6 loss. Patients with extensive nuclear staining were significantly older at diagnosis and were in continuous complete remission after a mean follow‐up of 75.7 months (range 27.5–121.2 months) from diagnosis. All three patients with focal nuclear staining of β‐catenin died within 36 months from diagnosis. Altogether, these data confirm and extend previous observations that CTNNB1‐mutated tumours represent a distinct molecular subgroup of medulloblastomas with favourable outcome, indicating that therapy de‐escalation should be considered. International consensus on the definition criteria of this distinct medulloblastoma subgroup should be achieved. Copyright

Medulloblastoma in childhood: progressive intellectual deterioration.

A series of 120 medulloblastomas in children operated on between 1967 and 1987 at the Hôpital des Enfants-Malades has been reviewed in order to check whether the conclusions of our study published 10 years ago have remained valid and, in particular, to verify whether the quality of life of these patients, which had been found to be poor at the time, had improved or worsened over the years. The postoperative mortality for the whole series was 6.5% there have been no deaths in the 35 patients operated on after 1980. The overall survival rate for the 120 children was 60% at 5 years and 53% at 10 years; for the patients who completed radiotherapy, the survival rates was 73% at 5 years and 64% at 10 years. Survival rates were surprisingly better in patients treated when under 6 years of age than in older children. They were also better in girls than in boys, and in desmoplastic compared with other medulloblastomas; however, the differences were not significant. When comparing the groups after total or subtotal resection of tumors, survival rates were not significantly different, but were lower in the small group of partial resections. Cell differentiation did not influence the prognosis. Psychological sequelae were significant and worsened over the years. Five years after treatment 58% of the children showed an IQ above 80; 5 years later this group included only 15% of the patients. These psychological sequelae were related to age at the time of radiotherapy: the younger the child, the lower the final IQ. Five years after treatment, 40% of the children had a normal academic level; 5 years later this group was reduced to 11%. Ten years after treatment, 36% of the patients were unempolyed and 64% worked in a protected environment. No patient had normal employment. These disastrous results concerning the quality of life of these medulloblastoma patients justify new trials with reduced doses of irradiation over the hemispheres, at least in low-risk groups.

Angiocentric neuroepithelial tumor (ANET) : A new epilepsy-related clinicopathological entity with distinctive MRI

Several types of glioneuronal tumors are known to induce intractable partial seizures in children and adults. The most frequent are dysembryoplastic neuroepithelial tumors (DNETs) and gangliogliomas. We report here a new clinicopathological entity within the spectrum of glioneuronal tumors observed in 10 children who underwent surgery for refractory epilepsy. These tumors demonstrate a unique, pathognomonic histological pattern and a specific appearance at magnetic resonance imaging (MRI). The most striking neuropathological feature is an angiocentric polarity of the tumor with gliofibrillary acidic protein (GFAP) positive fusiform and bipolar astrocytic cells arranged around blood vessels (perivascular cuffing with tumoral astrocytes). Characteristic MRI findings include involvement of cortical gray and white matter, intrinsically high signal on T1‐weighted images, as well as a stalk like extension to the ventricle. Immunohistochemical neuronal markers (neurofilament protein, synaptophysin and chromogranin) confirm the presence of a neuronal cell component. Therefore, the term angiocentric neuroepithelial tumor (ANET) is proposed.

hSNF5/INI1‐deficient tumours and rhabdoid tumours are convergent but not fully overlapping entities

Rhabdoid tumours (RTs) are rare but highly aggressive tumours of childhood. Their rarity and their miscellaneous locations make the diagnosis particularly challenging for pathologists. Central nervous system and peripheral RTs have been associated with biallelic inactivation of the hSNF5/INI1/SMARCB1 (hSNF5/INI1) tumour suppressor gene. Immunohistochemistry (IHC) with a monoclonal anti‐hSNF5/INI1 antibody has recently been proposed as an efficient diagnostic tool for RTs. We have conducted a retrospective study of 55 tumours referred to our institution with a suspicion of RT. This analysis included pathological review, IHC with anti‐hSNF5/INI1 antibody, and molecular investigation using quantitative DNA fluorescent analysis and sequencing of the nine exons of hSNF5/INI1. The molecular lesion could be detected in 37 of the 39 cases exhibiting negative staining for hSNF5/INI1. In the two discrepant cases, the lack of detection of genetic abnormality was probably owing to the presence of a high number of non‐tumour cells in the samples. This indicates that hSNF5/INI1 IHC is very sensitive and highly specific for the detection of hSNF5/INI1 loss‐of‐function. Among the 38 cases with typical RT histological features, six failed to exhibit hSNF5/INI1 mutation and stained positive for hSNF5/INI1. This strongly supports the evidence of a second genetic locus, distinct from hSNF5/INI1, associated with RT. Conversely, seven tumours with histological features poorly compatible with RT stained negative for hSNF5/INI1; they nevertheless exhibited an age of onset and a clinical behaviour similar to RT. This suggests that hSNF5/INI1 inactivation is not strictly limited to typical RT but characterizes a wider family of hSNF5/INI1‐deficient tumours. Consequently, we believe that anti‐hSNF5/INI1 IHC should be performed widely, even when the pathological characteristics are not typical. The molecular investigation should be performed in infants when a rhabdoid predisposition syndrome is suspected. Copyright

Immunocytochemical characterization of long-term persistent immune activation in human brain after herpes simplex encephalitis

The clinical, virological and immunocytochemical features of three children who recovered from acute herpes simplex encephalitis (HSE) before the age of 2 years, and who developed secondary severe focal epilepsy after a symptom‐free period, leading to neurosurgery 3–10 years later are described. In one child, relapse of HSE occurred immediately after surgery. In all three patients, brain sample biopsies showed abundant CD3‐positive T lymphocytes with a majority of CD8 cells, and abundant activated macrophage‐microglial cells, a pattern similar to that found in acute HSE. Herpes simplex virus DNA was retrieved from the tissue biopsy in one case. The long‐term persistent cerebral inflammatory process observed after HSE differed from that observed in another chronic viral disease, subacute sclerosing panencephalitis. This inflammatory reaction may be a result either of low‐grade viral expression or self‐induced immune activation. The role of inflammation in triggering epilepsy remains hypothetical. Solving these issues should have major therapeutic implications. Herpes simplex virus DNA latency in brain may be the source of replicative HSE relapse.

Comparative genomic hybridization detects specific cytogenetic abnormalities in pediatric ependymomas and choroid plexus papillomas

Pathogenesis and genetic abnormalities of ependymomas are not well known and differential diagnosis with choroid plexus tumors may be difficult when these tumors are located in the ventricles. We analyzed 16 samples of primary pediatric ependymomas and seven choroid plexus tumors for significant gains or losses of genomic DNA, using comparative genomic hybridization (CGH). Four ependymoma samples were obtained after surgery for relapse, including one patient whose tumor was analyzed at diagnosis and at first and second relapses. Three out of 16 ependymomas and none of the choroid plexus tumors appeared normal by CGH. In the remaining ependymomas, the number of regions with genomic imbalance was limited. The most frequent copy number abnormality in ependymomas was 22q loss. In one patient from whom multiple samples could be analyzed during tumor progression, no abnormality was present at diagnosis; gain of chromosome 9 and loss of 6q were observed at first relapse and, at second relapse, additional genomic imbalances were loss of 3p, 10q, and chromosome 15. In choroid plexus tumors, recurrent abnormalities were gains of chromosome 7 and region 12q. The recurrent chromosomal abnormalities were clearly different between ependymomas and choroid plexus papillomas (CPP). Recurrent loss of 22q suggests that this region harbors tumor suppressor genes important in the pathogenesis of ependymomas; however, other pathogenic pathways may exist involving 6q and chromosome 10 losses or gain of 1q and chromosome 9. CPP can be distinguished from ependymoma on the basis of CGH abnormalities.

Potent therapeutic activity of irinotecan (CPT-11) and its schedule dependency in medulloblastoma xenografts in nude mice

The anti‐tumor activity of irinotecan (CPT‐11), a DNA‐topoisomerase I inhibitor, was evaluated in 5 advanced stage subcutaneous medulloblastoma xenografts in nude mice, using different schedules of administration. With a 5‐day schedule, the highest i.v. dose tested (40 mg kg−1 day−1) induced complete regressions in all xenografts but 1, and delays in tumor growth always exceeded 30 days. Two xenografts, IGRM11 and IGRM33, were highly sensitive, and animals survived tumor‐free beyond 120 days after treatment. CPT‐11 clearly retained its anti‐tumor activity at a lower dosage (27 mg kg−1 day−1). CPT‐11 was significantly more active than cyclophosphamide, thiotepa and etoposide against the 3 xenografts evaluated. To study the schedule dependency of its anti‐tumor activity, CPT‐11 was given i.v. at the same total doses over the same period (33 days) using either a protracted or a sequential schedule in IGRM34‐bearing mice. With a dose of 10 mg kg−1 day−1 given on days 0–4, days 7–11, days 21–25 and days 28–32 (total dose, 200 mg kg−1), 3 of 6 animals were tumor free on day 378. The same total dose given with a sequential schedule, i.e., 20 mg kg−1 day−1 on days 0–4 and days 28–32, failed to induce complete regression. The plasma pharmacokinetics of CPT‐11 and SN‐38 were studied in IGRM34‐bearing animals after a single i.v. dose of 10 and 40 mg kg−1. The plasma clearance rate of CPT‐11 was dose dependent. The ratio between the SN‐38 and CPT‐11 area under the curve in plasma was 0.4–0.65, i.e., significantly higher than that observed in humans at the maximum tolerated dose (0.01–0.05). Conversely, this ratio was 10‐fold lower in tumor than in plasma. Clinical development of irinotecan is warranted in pediatric malignancies. Int. J. Cancer 73:156–163, 1997.

Intracranial Ewing sarcoma/'peripheral' primitive neuroectodermal tumor of dural origin with molecular genetic confirmation.

Ewing sarcoma/‘peripheral’ primitive neuroectodermal tumor (ES/pPNET) is the designation given to a family of small cell neoplasms that typically arise in bone or soft tissue and are unified by their common expression of the MIC2 antigen and specific translocations involving a gene on chromosome 22q12 [the most common being t(11;22)(q24;q12)]. ES/pPNET of intracranial origin is extraordinary. We report the case of a 6-year-old boy with a large left frontal region mass that adhered to dura and was extracerebral at surgery. Histologic study revealed a high-grade, undifferentiated-appearing neoplasm of small cell type that was negative on immunostudy for glial fibrillary acidic protein, synaptophysin, desmin, leukocyte common antigen, smooth muscle actin and epithelial membrane antigen, but positive for vimentin and neuron-specific enolase and diffusely labeled by antibody O13 (which recognizes the MIC2 gene product). RNA-based polymerase chain reaction assay confirmed the diagnosis of ES/pPNET by demonstrating fusion transcripts indicative of t(11;22) translocation. Bone scan, computerized tomography of the chest and bone marrow examination revealed no systemic tumor. The limited observations published to date suggest that primary intracranial ES/pPNET is most likely to present in childhood as a circumscribed, contrast-enhancing and dural-based extracerebral mass. It must be distinguished from a variety of small cell neoplasms, particularly PNETs of central neuroepithelial origin.

The management of desmoplastic neuroepithelial tumours in childhood.

Abstract The authors report on the clinicopathological aspects of and management strategies for the group of rare, large hemispheric childhood tumours recently classified as desmoplastic infantile ganglioglioma (DIGG), desmoplastic astrocytoma of infancy (DACI) and pleomorphic xanthoastrocytoma (PXA). Between 1985 and 1997, ten children (4 with DACIs, 4 with DIGGs and 2 with PXAs) with a median age of 9.5 months were operated on. All these patients had complete surgical resections, with two having a preoperative biopsy. This led to an erroneous diagnosis in both cases of malignant grade 4 astrocytoma. As a result, one patient had preoperative chemotherapy with no effect. There was one perioperative death. Histology revealed heterogeneous tumours with malignant looking areas in 8 of the specimens. None of the patients has had any postoperative adjuvant treatment. All surviving patients are alive at follow-up (median 4.2 years). Despite their often malignant appearance, these tumours have an excellent prognosis, but they can present formidable surgical challenges when they occur in very young age patients. We believe that surgical excision can offer a cure and that adjuvant treatment is not necessary. Finally, biopsy is of little value and may even lead to an erroneous diagnosis and subsequent mismanagement.