Two siblings with GAPO syndrome: Ophthalmic presentation and histopathologic findings

BACKGROUND

GAPO syndrome (growth retardation, alopecia, pseudoanodontia, optic atrophy) is a rare, autosomal recessive connective tissue disorder with only 60 reported cases. Ophthalmic manifestations vary and include hypertelorism, optic atrophy, and glaucoma. There have been three reported cases of GAPO syndrome with craniosynostosis.

MATERIALS/METHODS

We describe two new siblings with GAPO syndrome and craniosynostosis and the first histopathologic analysis of Tenon's capsule and extraocular muscle in this syndrome.

RESULTS

Both siblings presented with papilledema and V-pattern strabismus in addition to the alopecia, brittle eyelashes, growth retardation, and pseudoanodontia that characterize GAPO syndrome. Cranial vault expansion, though successful, was complicated by lack of distinct periosteal layers, thin dural adherence to bone, and extensive venous bleeding. Tenons encountered during strabismus surgery was inelastic and highly vascular. Histopathological analysis revealed hyalinization of Tenon's and a thickened, homogenized, amorphous appearance, similar to the extracellular matrix abnormalities described in skin and other organs Histopathological analysis of extraocular muscle was, in contrast, unremarkable.

CONCLUSIONS

GAPO impacts the extracellular matrix of Tenon's resulting in inelasticity and hypervascularity. Ophthalmologists should be mindful of these aberrant characteristics when planning surgery in this population.

Death after High-Dose rAAV9 Gene Therapy in a Patient with Duchenne's Muscular Dystrophy

We treated a 27-year-old patient with Duchenne's muscular dystrophy (DMD) with recombinant adeno-associated virus (rAAV) serotype 9 containing dSaCas9 (i.e., "dead" Staphylococcus aureus Cas9, in which the Cas9 nuclease activity has been inactivated) fused to VP64; this transgene was designed to up-regulate cortical dystrophin as a custom CRISPR-transactivator therapy. The dose of rAAV used was 1×1014 vector genomes per kilogram of body weight. Mild cardiac dysfunction and pericardial effusion developed, followed by acute respiratory distress syndrome (ARDS) and cardiac arrest 6 days after transgene treatment; the patient died 2 days later. A postmortem examination showed severe diffuse alveolar damage. Expression of transgene in the liver was minimal, and there was no evidence of AAV serotype 9 antibodies or effector T-cell reactivity in the organs. These findings indicate that an innate immune reaction caused ARDS in a patient with advanced DMD treated with high-dose rAAV gene therapy. (Funded by Cure Rare Disease.).

RARE-26. Evaluating the clinical utility of DNA methylation profiling for choroid plexus tumors

INTRODUCTION: Choroid plexus tumors (CPT) are rare, potentially aggressive CNS tumors with defined histologic criteria for grading. In recent years, several patients within our practice have demonstrated discordance between histological diagnosis and clinical behavior. DNA methylation profiling has emerged as a potential diagnostic adjunct for aiding clinical planning and treatment approach. In this study, we sought to retrospectively evaluate the clinical utility of DNA methylation profiling within our cohort of patients with CPT. METHODS: We performed a retrospective chart review of all patients with choroid plexus tumors treated at Dana-Farber / Boston’s Children’s Cancer and Blood Disorder Center between 1990-2021, evaluating the histology, treatment approach, and clinical outcome. Available tissue samples were sent to the National Institute of Health for DNA methylation profiling. RESULTS: Seventeen patients with CPT were identified. Median age at diagnosis was 1.8 years (range: 0.4-27.7). Histologic diagnosis included choroid plexus papilloma (CPP; n=4), atypical choroid plexus papilloma (aCPP; n=5), and choroid plexus carcinoma (CPC, n=8). DNA methylation in an initial subset placed these tumors with the pediatric type A (n=5), pediatric type B (n=6), and adult (n=1) subgroups. For one patient, methylation profiling returned as unclassifiable (possibly representing an alternative diagnosis). Discrepancies with the histologic grade were noted in several cases: one patient diagnosed with CPP grouped with pediatric type B CPT on methylation analysis, had rapid recurrence, and a diagnosis of CPC was made on a re-resection specimen; another patient with aCPP with concerning features was classified as pediatric type A by methylation, and is without evidence of disease after initial complete resection. Survival outcomes based on histologic diagnosis and molecular subgroups are compared and reported. CONCLUSION: DNA methylation profiling is a useful tool for the diagnosis of CPT and may have the potential to guide clinical planning and management.

DIPG-44. H3K27-altered diffuse midline gliomas with secondary driver molecular alterations

INTRODUCTION: Large-scale sequencing led to the identification of driver molecular alterations such as FGFR1 and BRAF in occasional diffuse midline gliomas (DMGs) H3K27-altered, but their significance is not completely explored. We evaluated these associations in our institutional cohorts. MATERIALS AND METHODS: We searched our sequencing data base (2013-2020) for H3K27M-mutant gliomas and analyzed the co-occurring genetic alterations. The demographics, clinical information, and pathology were reviewed. Copy number profiles were evaluated using BioDiscovery's Nexus Copy Number software package. Oncoplots and Kaplan-Meier survival curves were generated with the maftools R package. RESULTS: We identified 77 patients (age range 2-68, median 26). The diagnosis was DMG (n=55), anaplastic astrocytoma/glioblastoma (n=19), low-grade glioma (n=1), low-grade glioneuronal tumor (n=1), and ganglioglioma (n=1). Recurrent alterations were seen in TP53 (n=42), ATRX (n=17), NF1 (n=15), PDGFRA (n = 4). Five cases had BRAF V600E (1 ganglioglioma; 4 DMG); twelve had FGFR1 mutations (9 DMG; 3 anaplastic astrocytoma/glioblastoma). The most common location in the BRAF group was the brainstem and in the FGFR1 was the thalamus. Survival ranged from 0 to 97 months, median 12.9 months (28.8 months for FGFR1 and 22.8 for the BRAF V600E). This was not significantly different from OS reported in the literature for DMG.The BRAF V600E ganglioglioma patient is alive 37 months after diagnosis. CONCLUSION: There was no significant difference in outcomes for patients with secondary molecular drivers when compared with conventional H3K27M DMG. The outcome of the BRAF V600E tumors seemed to correlate with the histology. These findings and the possibility of targeted therapy argue for comprehensive sequencing of H3K27-altered gliomas.

Intracranial venous malformation masquerading as a meningioma in PI3KCA-related overgrowth spectrum disorder

Gain of function PIK3CA pathogenic variants have been identified in overgrowth syndromes collectively termed "PIK3CA-related overgrowth spectrum" (PROS). There are no previously reported cases of cerebrovascular venous malformations in PROS syndromes, though somatic activating PIK3CA variants have been identified in extracranial venous malformation. This study was approved by the Institutional Review Boar at Boston Children's Hospital. A 14-year-old female mosaic for the de novo p.R108H pathogenic variant in the PIK3CA gene was found to have a large tumor involving the superior sagittal sinus with mass effect on the motor cortex most consistent with a parafalcine meningioma. She underwent surgical resection with pathology demonstrating a venous malformation. PIK3CA pathogenic variants have been identified in nonsyndromic extracranial venous and lymphatic malformations as well in brain tumors, including glioma and meningioma. However, PIK3CA variants have not previously been identified in purely intracranial venous malformations. This distinction is relevant to treatment decisions, given that mTOR inhibitors may provide an alternative option for noninvasive therapy in cases of suspected venous malformation.

Spatiotemporal changes in diffusivity and anisotropy in fetal brain tractography

Population averaged diffusion atlases can be utilized to characterize complex microstructural changes with less bias than data from individual subjects. In this study, a fetal diffusion tensor imaging (DTI) atlas was used to investigate tract-based changes in anisotropy and diffusivity in vivo from 23 to 38 weeks of gestational age (GA). Healthy pregnant volunteers with typically developing fetuses were imaged at 3 T. Acquisition included structural images processed with a super-resolution algorithm and DTI images processed with a motion-tracked slice-to-volume registration algorithm. The DTI from individual subjects were used to generate 16 templates, each specific to a week of GA; this was accomplished by means of a tensor-to-tensor diffeomorphic deformable registration method integrated with kernel regression in age. Deterministic tractography was performed to outline the forceps major, forceps minor, bilateral corticospinal tracts (CST), bilateral inferior fronto-occipital fasciculus (IFOF), bilateral inferior longitudinal fasciculus (ILF), and bilateral uncinate fasciculus (UF). The mean fractional anisotropy (FA) and mean diffusivity (MD) was recorded for all tracts. For a subset of tracts (forceps major, CST, and IFOF) we manually divided the tractograms into anatomy conforming segments to evaluate within-tract changes. We found tract-specific, nonlinear, age related changes in FA and MD. Early in gestation, these trends appear to be dominated by cytoarchitectonic changes in the transient white matter fetal zones while later in gestation, trends conforming to the progression of myelination were observed. We also observed significant (local) heterogeneity in within-tract developmental trajectories for the CST, IFOF, and forceps major.

White matter mean diffusivity correlates with myelination in tuberous sclerosis complex

Objective

Diffusion tensor imaging (DTI) of the white matter is a biomarker for neurological disease burden in tuberous sclerosis complex (TSC). To clarify the basis of abnormal diffusion in TSC, we correlated ex vivo high‐resolution diffusion imaging with histopathology in four tissue types: cortex, tuber, perituber, and white matter.

Methods

Surgical specimens of three children with TSC were scanned in a 3T or 7T MRI with a structural image isotropic resolution of 137–300 micron, and diffusion image isotropic resolution of 270‐1,000 micron. We stained for myelin (luxol fast blue, LFB), gliosis (glial fibrillary acidic protein, GFAP), and neurons (NeuN) and registered the digitized histopathology slides (0.686 micron resolution) to MRI for visual comparison. We then performed colocalization analysis in four tissue types in each specimen. Finally, we applied a linear mixed model (LMM) for pooled analysis across the three specimens.

Results

In white matter and perituber regions, LFB optical density measures correlated with fractional anisotropy (FA) and inversely with mean diffusivity (MD). In white matter only, GFAP correlated with MD, and inversely with FA. In tubers and in the cortex, there was little variation in mean LFB and GFAP signal intensity, and no correlation with MRI metrics. Neuronal density correlated with MD. In the analysis of the combined specimens, the most robust correlation was between white matter MD and LFB metrics.

Interpretation

In TSC, diffusion imaging abnormalities in microscopic tissue types correspond to specific histopathological markers. Across all specimens, white matter diffusivity correlates with myelination.

Clinical targeted exome-based sequencing in combination with genome-wide copy number profiling: precision medicine analysis of 203 pediatric brain tumors

Background

Clinical genomics platforms are needed to identify targetable alterations, but implementation of these technologies and best practices in routine clinical pediatric oncology practice are not yet well established.

Methods

Profile is an institution-wide prospective clinical research initiative that uses targeted sequencing to identify targetable alterations in tumors. OncoPanel, a multiplexed targeted exome-sequencing platform that includes 300 cancer-causing genes, was used to assess single nucleotide variants and rearrangements/indels. Alterations were annotated (Tiers 1-4) based on clinical significance, with Tier 1 alterations having well-established clinical utility. OncoCopy, a clinical genome-wide array comparative genomic hybridization (aCGH) assay, was also performed to evaluate copy number alterations and better define rearrangement breakpoints.

Results

Cancer genomes of 203 pediatric brain tumors were profiled across histological subtypes, including 117 samples analyzed by OncoPanel, 146 by OncoCopy, and 60 tumors subjected to both methodologies. OncoPanel revealed clinically relevant alterations in 56% of patients (44 cancer mutations and 20 rearrangements), including BRAF alterations that directed the use of targeted inhibitors. Rearrangements in MYB-QKI, MYBL1, BRAF, and FGFR1 were also detected. Furthermore, while copy number profiles differed across histologies, the combined use of OncoPanel and OncoCopy identified subgroup-specific alterations in 89% (17/19) of medulloblastomas.

Conclusion

The combination of OncoPanel and OncoCopy multiplex genomic assays can identify critical diagnostic, prognostic, and treatment-relevant alterations and represents an effective precision medicine approach for clinical evaluation of pediatric brain tumors.

Rasmussen's encephalitis presenting as focal cortical dysplasia

Rasmussen's encephalitis is a rare syndrome characterized by intractable seizures, often associated with epilepsia partialis continua and symptoms of progressive hemispheric dysfunction. Seizures are usually the hallmark of presentation, but antiepileptic drug treatment fails in most patients and is ineffective against epilepsia partialis continua, which often requires surgical intervention. Co-occurrence of focal cortical dysplasia has only rarely been described and may have implications regarding pathophysiology and management. We describe a rare case of dual pathology of Rasmussen's encephalitis presenting as a focal cortical dysplasia (FCD) and discuss the literature on this topic.

Primary calcified rhabdoid meningioma of the cranio-cervical junction: A case report and review of literature

Rhabdoid meningioma (RM) is a relatively new, rare, and aggressive subtype of meningioma, classified as Grade III malignancy in 2000, 2007 versions of WHO classification of the central nervous system. We reviewed the data available from all published cases of RMs. To the best of our knowledge, there are more than 100 published cases of RMs; none have documented extensive calcification or origin from the cranio cervical junction. We report the first case of a totally calcified (stony mass), primary RM, at the cranio cervical junction. Also, we highlighted the role of the transcondylar approach to achieve microscopic total removal of such a challenging lesion. A 37 year old female, allergic to erythromycin, presented with 5 years of progressive right upper extremity numbness and weakness, right facial numbness, and occipital pain. Imaging demonstrated a large calcified mass at the right posterior–lateral margin of the cranio cervical junction, encasing the right vertebral artery and right PICA loop. Patient underwent microscopic total resection of the lesion. Pathological diagnosis was confirmed as RM with atypical features. Subsequently, the patient received postoperative intensity modulated radiotherapy (IMRT) on the tumor bed, and close follow up imaging showed no recurrence 2 years after surgery. We report the first case of a primary RM originating from the cranial cervical junction; also, it is the first case to present with extensive calcification in this morphological subtype. We also conclude that RM has now become a feature of newly diagnosed cases and not only a disease of recurrent cases as it was thought in the past. Since RMs are typically considered aggressive, total surgical resection with close follow up and postoperative adjuvant radiation should be considered. However, the adjuvant therapy of each separate case of RM should be tailored according to its particular histopathologic profile.

Extracranial metastases of glioblastoma in a child: case report and review of the literature

Glioblastoma (GBM) is the most common adult malignant brain tumor but is notably less common in children. Primary brain tumors rarely metastasize outside the central nervous system and when metastases occur, it is often in patients with diversionary shunting of the cerebrospinal fluid. This report details the case of a 13(1/2)-year-old boy who was diagnosed with GBM. He survived 10 months after diagnosis. At autopsy, the tumor was found to extensively infiltrate the leptomeninges as well as the cranial skin and soft tissue. Further examination disclosed multiple liver and lung metastatic GBM nodules. This pattern of spread is very uncharacteristic of gliomas and emphasizes the importance of adequate metastatic evaluation.

Neuroenteric cyst of the optic nerve: case report with immunohistochemical study

A 36 year old man developed slowly progressive unilateral visual loss due to a cystic lesion of the intraorbital optic nerve. Pathologically the lesion was an epithelium lined cyst entirely within the atrophic nerve. The cyst lining consisted of columnar epithelium partly pseudostratified and ciliated with evidence of mucin secretion, and was immunoactive for cytokeratin but not glial fibrillary acidic protein. This lesion is considered to be similar to neuroenteric cysts that have been reported elsewhere in the nervous system, and the immunocytochemical results are consistent with a heterotopia derived from the primitive ectoderm of the stomatodeum.