Mosaic PTEN alteration in the neural crest during embryogenesis results in multiple nervous system hamartomas.

The contribution of mosaic alterations to tumors of the nervous system and to non-malignant neurological diseases has been unmasked thanks to the development of Next Generation Sequencing (NGS) technologies. We report here the case of a young patient without any remarkable familial medical history who was first referred at 7 years of age, for an autism spectrum disorder (ASD) of Asperger type, not associated with macrocephaly. The patient subsequently presented at 10 years of age with multiple nodular lesions located within the trigeminal, facial and acoustic nerve ganglia and at the L3 level. Histological examination of this latter lesion revealed a glioneuronal hamartoma, exhibiting heterogeneous PTEN immunoreactivity, astrocyte and endothelial cell nuclei expressing PTEN, but not ganglion cells. NGS performed on the hamartoma allowed the detection of a PTEN pathogenic variant in 30% of the reads. The presence of this variant in the DNA extracted from blood and buccal swabs in 3.5 and 11% of the NGS reads, respectively, confirmed the mosaic state of the PTEN variant. The anatomical distribution of the lesions suggests that the mutational event affecting PTEN occurred in neural crest progenitors, thus explaining the absence of macrocephaly. This report shows that mosaic alteration of PTEN may result in multiple central and peripheral nervous system hamartomas and that the presence of such alteration should be considered in patients with multiple nervous system masses, even in the absence of cardinal features of PTEN hamartoma tumor syndrome, especially macrocephaly.

Multi-Photon Time Lapse Imaging to Visualize Development in Real-time: Visualization of Migrating Neural Crest Cells in Zebrafish Embryos.

Congenital eye and craniofacial anomalies reflect disruptions in the neural crest, a transient population of migratory stem cells that give rise to numerous cell types throughout the body. Understanding the biology of the neural crest has been limited, reflecting a lack of genetically tractable models that can be studied in vivo and in real-time. Zebrafish is a particularly important developmental model for studying migratory cell populations, such as the neural crest. To examine neural crest migration into the developing eye, a combination of the advanced optical techniques of laser scanning microscopy with long wavelength multi-photon fluorescence excitation was implemented to capture high-resolution, three-dimensional, real-time videos of the developing eye in transgenic zebrafish embryos, namely Tg(sox10:EGFP) and Tg(foxd3:GFP), as sox10 and foxd3 have been shown in numerous animal models to regulate early neural crest differentiation and likely represent markers for neural crest cells. Multi-photon time-lapse imaging was used to discern the behavior and migratory patterns of two neural crest cell populations contributing to early eye development. This protocol provides information for generating time-lapse videos during zebrafish neural crest migration, as an example, and can be further applied to visualize the early development of many structures in the zebrafish and other model organisms.

Occipital cephalocele with neural crest remnants? Radiological and pathological findings in a newborn boy.

PURPOSE: A cephalocele is a congenital anomaly involving the herniation of intracranial tissue from a skull defect. The sac containing the central nervous system (CNS) with the ventricle system is called the encephalocystocele. An atretic cephalocele is thought to be an abortive form of cephalocele, and the essential nature is still controversial. CASE REPORT: Here, we report the case of a newborn boy with an occipital cephalocele containing a small cystic component which was composed of ependymal cells and the immature CNS tissue. A newborn boy was admitted to our hospital because of an occipital mass, which was about 2.5 cm in diameter, located at the posterior midline, and covered with alopetic skin without CSF leakage. He had a cleft palate. Magnetic resonance imaging (MRI) clearly showed an occipital cephalocele with a tiny cystic component connecting to the subarachnoid space. MRI also showed mild hydrocephalus, hypoplasia of the corpus callosum and tentorium cerebelli, dropping down of the bilateral occipital lobes and vermicular agenesis. We performed the extirpation of the subscalp module under general anesthesia and histologically examined the resected mass. On immunohistopathological examination, most part of the subscalp module was fibrous tissue with numerous vessels and meningeal origin cells. In a small part of the innermost layer, we found a small island consisting of CNS tissue and a tiny cyst lined with a single layer of ependymal cells. CONCLUSION: Based on radiological and immunohistopathological findings, we speculate that the cystic component at the base of the nodule seems to correspond to neural crest remnants but not to true herniation of the brain and cerebral ventricles.

A pre-clinical murine model of oral implant osseointegration.

Many of our assumptions concerning oral implant osseointegration are extrapolated from experimental models studying skeletal tissue repair in long bones. This disconnect between clinical practice and experimental research hampers our understanding of bone formation around oral implants and how this process can be improved. We postulated that oral implant osseointegration would be fundamentally equivalent to implant osseointegration elsewhere in the body. Mice underwent implant placement in the edentulous ridge anterior to the first molar and peri-implant tissues were evaluated at various timepoints after surgery. Our hypothesis was disproven; oral implant osseointegration is substantially different from osseointegration in long bones. For example, in the maxilla peri-implant pre-osteoblasts are derived from cranial neural crest whereas in the tibia peri-implant osteoblasts are derived from mesoderm. In the maxilla, new osteoid arises from periostea of the maxillary bone but in the tibia the new osteoid arises from the marrow space. Cellular and molecular analyses indicate that osteoblast activity and mineralization proceeds from the surfaces of the native bone and osteoclastic activity is responsible for extensive remodeling of the new peri-implant bone. In addition to histologic features of implant osseointegration, molecular and cellular assays conducted in a murine model provide new insights into the sequelae of implant placement and the process by which bone is generated around implants.

Masticatory muscle defects in hemifacial microsomia: a new embryological concept.

First arch syndromes correspond to a wide spectrum of human latero-facial congenital anomalies affecting cranial neural crest cells (CNCCs) derivatives of the first pharyngeal arch (PA1). The abnormal traits display variable quantitative expression and are often unilateral. Mandibular skeletal defects are invariably accompanied by hypoplasia or agenesis of masticatory muscles, but no explanation has been proposed for this association. Indeed, during embryonic development, CNCCs give only rise to skeletal components of the head while muscles derive from cephalic myogenic mesodermal cells (CMMCs). Recent studies on animal models have shown that communication between CNCCs and CMMCs is essential for the development of masticatory muscles: genetic lesions affecting only CNCCs can prevent muscularization of the jaws. To evaluate the involvement of CNCC/CMMC interactions in human craniofacial development, we performed a quantitative analysis of masticatory muscle and mandibular bone volumes on craniofacial CT-scans from 8 children, ages 3 months to 16 years, affected by hemifacial microsomia. We found that: (1) in seven patients the masseter muscle is absent in the affected side; (2) the absence of masseter is correlated neither with the age of the patients nor with the volume and shape of the affected ramus; and (3) in all cases the pterygoid and the temporal muscles are either reduced or absent. Our findings suggest that an early developmental event is the origin of the muscular defects in these patients. We propose that the hypoplasia or agenesis of masticatory muscles derives from a defect in the CNCCs/CMMCs communication during early embryonic development.

Neural crest-specific loss of Prkar1a causes perinatal lethality resulting from defects in intramembranous ossification.

The cranial neural crest (CNC) undergoes complex molecular and morphological changes during embryogenesis in order to form the vertebrate skull, and nearly three quarters of all birth defects result from defects in craniofacial development. The molecular events leading to CNC differentiation have been extensively studied; however, the role of the cAMP-dependent protein kinase [protein kinase A (PKA)] during craniofacial development has only been described in palate formation. Here, we provide evidence that strict PKA regulation in postmigratory CNC cells is essential during craniofacial bone development. Selective inactivation of Prkar1a, a regulatory subunit of the PKA holoenzyme, in the CNC results in perinatal lethality caused by dysmorphic craniofacial development and subsequent asphyxiation. Additionally, aberrant differentiation of CNC mesenchymal cells results in anomalous intramembranous ossification characterized by formation of cartilaginous islands in some areas and osteolysis of bony trabeculae with fibrous connective tissue stabilization in others. Genetic interaction studies revealed that genetic reduction of the PKA catalytic subunit C(alpha) was able to rescue the phenotype, whereas reduction in Cbeta had no effect. Overall, these observations provide evidence of the essential role of proper regulation of PKA during the ossification of the bones of the skull. This knowledge may have implications for the understanding and treatment of craniofacial birth defects.

Value of FDG PET imaging in the management of patients with thyroid, neuroendocrine, and neural crest tumors.

OBJECTIVES: The purpose of this study was to evaluate the value and impact on management of FDG PET imaging in patients with biopsy-proved neuroendocrine and neural crest tumors, as well as thyroid carcinoma of various types. MATERIALS AND METHODS: This is a retrospective review of imaging and clinical data of 60 consecutive patients presenting for evaluation of suspected recurrence who underwent FDG PET imaging between August 1993 and February 2002. All patients were referred for PET because of equivocal findings on conventional evaluation (most often increasing tumor markers and negative conventional workup) or for restaging. The final diagnosis was established with pathology (n = 19) or at least 6 months of follow-up (n = 41). The FDG images were acquired 1 hour after the intravenous administration of 10 mCi FDG with 1 of 2 dedicated PET tomographs (Siemens ECAT 933, CTI, Knoxville, TN; and GE Advance, General Electric Medical Systems, Milwaukee, WI). RESULTS: Thirty-four patients had recurrent disease and 26 had no evidence of recurrence. FDG PET imaging revealed at least as many focal abnormalities as concurrent CT, magnetic resonance, or other nuclear imaging modalities in 46 of 60 patients (77%). There were 17 patients (28%) in whom FDG PET found abnormalities not seen with other modalities. In the small group (n = 18) of cases of carcinoid, pheochromocytoma, Merkel cell tumor, and neuroblastoma, all cases were true positive (T+) or true negative (T-). In the group of 42 cases of thyroid carcinoma, the sensitivity was 67%. There were 16 T+, 18 T-, and 8 false-negative (F-) cases. Six F- cases presented with increasing thyroglobulin levels and negative whole-body I-131 scans. Four of these 6 F- cases were proved by surgery, 1 by a positive post I-131 therapy scan, and 1 by normalization of thyroglobulin levels after I-131 therapy. Two of the 8 F- PET cases had a positive I-131 scan. FDG PET imaging had an impact on the management of 13 of 60 of these patients (22%) by demonstrating extensive metastases and cancelling surgery (n = 2), and by detecting recurrence and guiding surgery (n = 5) or radiation therapy (n = 6). CONCLUSIONS: FDG PET is helpful in the evaluation of thyroid, neuroendocrine, and neural crest tumors. Although the sensitivity was only 76%, there were no false-positive findings, and FDG PET findings changed the management of 22% of the patients.

Metaiodobenzylguanidine total-body scintigraphy required for revealing occult neuroblastoma in opsoclonus-myoclonus syndrome.

UNLABELLED: A girl aged 13 months presented with clinical features of subacute progressive ataxia leading to abasia, astasia, loss of unsupported sitting and apraxia. In addition, an opsoclonus, myoclonia and introvert behaviour developed. MRI of the brain, EEG, extensive tests of blood, urine and CSF showed no abnormalities. Based on clinical symptoms only, the diagnosis of opsoclonus-myoclonus syndrome (OMS) could be made. Under the suspicion of a neuroblastoma, further investigations were performed: a lateral and antero-posterior X-ray examination of the chest showed no tumour; neither did ultrasound of the abdomen. Concentrations of catecholamines and their metabolites in 24 h urine were normal and none of five tested anti-neuronal antibodies were found. However, a total-body scintigraphy with [I(123)] metaiodobenzylguanidine (MIBG) revealed a paravertebral hot spot on the left side compatible with a neural crest tumour. A MRI scan of the abdomen confirmed the supraphrenic lesion. [I(123)]MIBG uptake was sufficient for [I(131)]MIBG therapy. The response of the tumour to this therapy was favourable. The neurological symptoms of the patient slightly improved under steroid treatment. CONCLUSION: Opsoclonus-myoclonus syndrome is a serious disease in infants, sometimes associated with occult neuroblastoma for which a full oncological work-up, including metaiodobenzylguanidine total-body scintigraphy is required.

Does simple estimation of 131I-metaiodobenzylguanidine uptake in patients with neural crest tumours correlate with clinical outcome?

A retrospective study was undertaken in six patients (three male and three female) with neural crest tumours who received therapeutic doses of 131I-meta-iodobenzylguanidine (131I-MIBG) (6.7-10.5 GBq). The age range of the patients was 13-65 years (mean 36 years). Quantification of tumour uptake was obtained from images acquired with a large-field-of-view gamma camera on a single occasion between 2 and 10 days post-treatment. Tumour uptake was calculated to be 0.1% and 3.2% of the administered dose, corresponding to uptakes of 6.7-142.8 MBq. Tumour volume was assessed from computed tomography (CT) or magnetic resonance (MR) images and estimates of tumour dose made from the Medical Internal Radiation Dosimetry scheme (MIRD) tables. Estimated doses were between 7 and 113 Gy. Most significantly, our findings indicate that high tumour uptake did not always correlate with good clinical response.

131I-MIBG scintigraphy in neural crest tumours.

Radioiodinated meta-iodobenzylguanidine (131I-MIBG) has been widely used for the diagnosis of neuroblastomas, pheochromocytomas, paragangliomas and medullary carcinomas of thyroid. We have developed a procedure for preparation of 131I-MIBG and studied its utility in diagnosis of primary and metastatic neural crest tumours. Studies were carried out in 54 patients. Of them 39 cases were of neuroblastomas, 1 pheochromocytoma; 6 operated medullary carcinomas; 5 paragangliomas; 2 Ewing's sarcoma and 1 Rhabdomyosarcoma; The sensitivity for the detection of primary tumours of neuroblastomas was 94% and for the detection of metastasis was 83%; while in the case of paragangliomas and medullary carcinoma, the sensitivity was 75% and 70% respectively. Our experience in the present study shows that 131I-MIBG scintigraphy is a sensitive and specific diagnostic tool to localise primary and metastatic disease of neural crest tumours.

Beckwith-wiedemann syndrome and neural crest tumors. A report of two cases.

We report 2 cases of thoracic neural crest tumors complicating the course in patients with Beckwith-Wiedemann syndrome (BWS). In the first patient, a thoracic neuroblastoma was fortuitously discovered at age 3 months on a chest film prior to a partial glossectomy. In the follow-up left nephroblastoma and a right kidney simple cyst appeared. In the second patient, a thoracic tumor which proved to be a mature ganglioneuroma was discovered at age 4 years on a follow up spinal radiograph. Although less frequent than nephroblastoma and/or adrenal tumors, the occurrence of thoracic neuroblastoma in BWS suggests that periodic chest radiograph and assays of HVA, VMA and Dopamine should be included in the follow-up protocol.