Malignant transformation of a desmoplastic infantile ganglioglioma

Epigenetic Regulation in Primary CNS Tumors: An Opportunity to Bridge Old and New WHO Classifications

Originally approved in 1979, a specific grading classification for central nervous system (CNS) tumors was devised by the World Health Organization (WHO) in an effort to guide cancer treatment and better understand prognosis. These "blue books" have since undergone several iterations based on tumor location, advancements in histopathology, and most recently, diagnostic molecular pathology in its fifth edition. As new research methods have evolved to elucidate complex molecular mechanisms of tumorigenesis, a need to update and integrate these findings into the WHO grading scheme has become apparent. Epigenetic tools represent an area of burgeoning interest that encompasses all non-Mendelian inherited genetic features affecting gene expression, including but not limited to chromatin remodeling complexes, DNA methylation, and histone regulating enzymes. The SWItch/Sucrose non-fermenting (SWI/SNF) chromatin remodeling complex is the largest mammalian family of chromatin remodeling proteins and is estimated to be altered in 20-25% of all human malignancies; however, the ways in which it contributes to tumorigenesis are not fully understood. We recently discovered that CNS tumors with SWI/SNF mutations have revealed an oncogenic role for endogenous retroviruses (ERVs), remnants of exogenous retroviruses that integrated into the germline and are inherited like Mendelian genes, several of which retain open reading frames for proteins whose expression putatively contributes to tumor formation. Herein, we analyzed the latest WHO classification scheme for all CNS tumors with documented SWI/SNF mutations and/or aberrant ERV expression, and we summarize this information to highlight potential research opportunities that could be integrated into the grading scheme to better delineate diagnostic criteria and therapeutic targets.

Establishment and Characterization of Brain Cancer Primary Cell Cultures From Patients to Enable Phenotypic Screening for New Drugs

Aim: Desmoplastic infantile ganglioglioma (DIG), is a rare tumor arising mainly during the first 2 years of life. Molecular characterization of these benign yet rapidly proliferating tumors has been limited to evaluating a few mutations in few genes. Our aim was to establish a live cell culture to enable the understanding of the cellular processes driving the non-malignant growth of these tumors.

Methods: Tumor tissue from a rare non-infantile 8-year-old female DIG patient was dissociated and digested using collagenase to establish live cultures. Both 2D monolayer and 3D neurospheres were successfully cultured and characterized for proliferative potential, intrinsic plasticity, presence of cancer stem cells and the expression of stem cell markers. Cells cultured as 3D were embedded as tissue blocks. Immunohistochemistry was performed in both tissue and 3D sections for markers including synaptophysin, vimentin, neurofilament and MIB-1. Mutation analysis by NGS was performed using a-100 gene panel.

Results: Using immunohistochemistry, the 3D cultures were shown to express markers as in the original DIG tumor tissue indicating that the spheroid cultures were able to maintain the heterogeneity found in the original tumor. Cells continued proliferating past passage 10 indicative of immortalization. Enrichment of cancer stem cells was observed in neurospheres by FACS using CD133 antibody and RT-PCR. Mutation analysis indicated the presence of germline mutations in three genes and somatic mutations in two other genes.

Conclusion: A spontaneous cell line-like cell culture with high percentage of stem cells has been established from a DIG tumor for the first time.

The molecular characteristics of low-grade and high-grade areas in desmoplastic infantile astrocytoma/ganglioglioma

AIMS

Desmoplastic infantile astrocytomas and gangliogliomas (DIA/DIGs) are rare brain tumours of infancy. A distinctive feature of their histopathology is a combination of low-grade and high-grade features. Most DIA/DIGs can be surgically resected and have a good prognosis. However, high-grade features often dominate recurrent tumours, some of which have a poor outcome. In this study, we test the hypothesis that low-grade and high-grade areas in DIA/DIGs have distinct molecular characteristics.

METHODS

Tissue samples from microdissected low-grade and high-grade areas in 12 DIA/DIGs were analysed by DNA methylation profiling, whole exome sequencing, RNA sequencing and immunohistochemistry to search for potential differences at multiple molecular levels.

RESULTS

Copy number variants among tumours and between the two morphologically distinct areas were infrequent. No recurrent genetic alterations were identified across the tumour series, and high-grade areas did not have additional genetic alterations to explain their distinct morphology or biological behaviour. However, high-grade areas showed relative hypomethylation in genes downstream of the transcription factors SOX9 and LEF1 and evidence of a core SOX9 transcription network alongside activation of the BMP, WNT, and MAPK signalling pathways.

CONCLUSIONS

This study contributes to our knowledge of molecular genetic alterations in DIA/DIGs, uncovers molecular differences between the two distinct cell populations in these tumours, and suggests potential therapeutic targets among the more proliferative cell population in DIA/DIGs.

Predictors of mortality and tumor recurrence in desmoplastic infantile ganglioglioma and astrocytoma-and individual participant data meta-analysis (IPDMA)

PURPOSE

Desmoplastic infantile astrocytoma (DIA) and desmoplastic infantile ganglioglioma (DIG) are classified together as grade I neuronal and mixed neuronal-glial tumor of the central nervous system by the World Health Organization (WHO). These tumors are rare and have not been well characterized in terms of clinical outcomes. We aimed to identify clinical predictors of mortality and tumor recurrence/progression by performing an individual patient data meta-analysis (IPDMA) of the literature.

METHODS

A systematic literature review from 1970 to 2020 was performed, and individualized clinical data for patients diagnosed with DIA/DIG were extracted. Aggregated data were excluded from collection. Outcome measures of interest were mortality and tumor recurrence/progression, as well as time-to-event (TTE) for each of these. Participants without information on these outcome measures were excluded. Cox regression survival analyses were performed to determine predictors of mortality and tumor recurrence / progression.

RESULTS

We identified 98 articles and extracted individual patient data from 188 patients. The cohort consisted of 58.9% males with a median age of 7 months. The majority (68.1%) were DIGs, while 24.5% were DIAs and 7.5% were non-specific desmoplastic infantile tumors; DIAs presented more commonly in deep locations (p = 0.001), with leptomeningeal metastasis (p = 0.001), and was associated with decreased probability of gross total resection (GTR; p = 0.001). Gender, age, and tumor pathology were not statistically significant predictors of either mortality or tumor recurrence/progression. On multivariate survival analysis, GTR was a predictor of survival (HR = 0.058; p = 0.007) while leptomeningeal metastasis at presentation was a predictor of mortality (HR = 3.27; p = 0.025). Deep tumor location (HR = 2.93; p = 0.001) and chemotherapy administration (HR = 2.02; p = 0.017) were associated with tumor recurrence/progression.

CONCLUSION

Our IPDMA of DIA/DIG cases reported in the literature revealed that GTR was a predictor of survival while leptomeningeal metastasis at presentation was associated with mortality. Deep tumor location and chemotherapy were associated with tumor recurrence / progression.

Infantile and Noninfantile Desmoplastic Astrocytoma and Ganglioglioma: Only Different Age of Onset?

OBJECTIVE

The purpose of this study was to investigate clinical, pathological, and prognostic discrepancies between infantile and noninfantile desmoplastic astrocytoma/ganglioglioma patients.

METHODS

From January 2012 to December 2019, we retrospectively reviewed patients aged <18 years who underwent craniotomies at Beijing Tiantan Hospital. Patients diagnosed with desmoplastic infantile astrocytoma and ganglioglioma (DIA/DIG) were included.

RESULTS

The group consisted of 9 infantile patients and 8 noninfantile patients. The mean age of onset was 30.11 months in infantile patients and 103.75 months in noninfantile patients. Comparing with infantile patients, noninfantile patients had a mild female predominance (P = 0.335). The most common presentation in noninfantile patients was seizure (n = 4, 50%), whereas abnormal head circumference (n = 3, 33.3%) was the most common presentation in the infantile group. All cases showed a ki-67 index <2%. Preoperative tumor volume in infantile patients (213.98 cm³) was larger than that in noninfantile patients (21.99 cm³) (P = 0.043). Gross total resection was achieved in 5 (55.6%) infantile patients and 6 (75%) noninfantile patients (P = 0.62). All patients are alive by last follow-up visit, and 1 infantile patient recurred 8 months postoperative.

CONCLUSIONS

Infantile and noninfantile patients with DIA/DIGs share similar clinical and histopathological features. Compared with infantile patients, noninfantile patients tend to have different symptom predominance. Lesions in noninfantile patients are prone to present with different cystic-solid patterns and smaller volume. Patients with DIA/DIGs have favorable prognosis regardless of extent of resection.

Desmoplastic Infantile Ganglioglioma: A MAPK Pathway-Driven and Microglia/Macrophage-Rich Neuroepithelial Tumor

MAPK pathway activation has been recurrently observed in desmoplastic infantile ganglioglioma/astrocytoma (DIG/DIA) with reported disproportionally low mutation allele frequencies relative to the apparent high tumor content, suggesting that MAPK pathway alterations may be subclonal. We sought to expand the number of molecularly profiled cases and investigate if tumor cell composition could account for the observed low mutation allele frequencies. Molecular (targeted neuro-oncology next-generation sequencing/RNA sequencing and OncoScan microarray) and immunohistochemical (CD68-PGM1/CD163/CD14/CD11c/lysozyme/CD3/CD20/CD34/PD-L1) studies were performed in 7 DIG. Activating MAPK pathway alterations were identified in 4 (57%) cases: 3 had a BRAF mutation (V600E/V600D/V600_W604delinsDQTDG, at 8%–27% variant allele frequency) and 1 showed a TPM3-NTRK1 fusion. Copy number changes were infrequent and nonrecurrent. All tumors had at least 30% of cells morphologically and immunophenotypically consistent with microglial/macrophage lineage. Two subtotally resected tumors regrew; 1 was re-excised and received adjuvant treatment (chemotherapy/targeted therapy), with clinical response to targeted therapy only. Even with residual tumor, all patients are alive (median follow-up, 83 months; 19–139). This study further supports DIG as another MAPK pathway-driven neuroepithelial tumor, thus expanding potential treatment options for tumors not amenable to surgical cure, and suggests that DIG is a microglia/macrophage-rich neuroepithelial tumor with frequent low driver mutation allele frequencies.

Mixed Solid and Cystic Mass in an Infant

Desmoplastic infantile tumors are rare supratentorial brain tumors that occur in pediatric patients. Desmoplastic infantile tumors are made up of 2 subtypes: desmoplastic infantile gangliogliomas and desmoplastic infantile astrocytomas. Desmoplastic infantile tumors are often identifiable on imaging on the basis of multiple characteristics. Nevertheless, pathologic analysis is required to confirm the diagnosis, particularly when the imaging features are atypical. Here, the radiology findings, surgical approach and subsequent management, and pathology of a desmoplastic infantile ganglioglioma are described.

The great neurosurgical masquerader: 3 cases of desmoplastic infantile ganglioglioma

Desmoplastic infantile ganglioglioma (DIG) is a rare, distinctive, supratentorial neoplasm with a generally favorable prognosis. Clinical, radiographic, and pathologic features can sometimes mimic those of a malignant tumor and other serious intracranial disorders. The author describes his experience with 3 cases of DIG, each of which initially masqueraded as another neurological disease with a very different prognosis. Case 1 was an infant boy referred for evaluation of a hemorrhagic infarction at birth. Case 2 was an infant girl referred for evaluation of a holohemispheric malignant neoplasm. Case 3 was an infant girl referred for evaluation of an intracranial mass believed to be a subdural empyema or possible sarcoma. In each case the lesion was resected and found to be a WHO grade I DIG. Each child has had a benign postoperative course. DIG can be mistaken for other serious neurological conditions including malignant neoplasm, cerebral infarction, and infection. It is prudent to consider this rare, low-grade resectable tumor in the differential diagnosis of atypical intracranial masses of childhood, as the impact on prognosis can be profound. The author discusses management strategies for DIG, including a role for molecular sequencing.

Desmoplastic Infantile Ganglioglioma/Astrocytoma (DIG/DIA) Are Distinct Entities with Frequent BRAFV600 Mutations

Desmoplastic infantile ganglioglioma (DIG) and desmoplastic infantile astrocytoma (DIA) are extremely rare tumors that typically arise in infancy; however, these entities have not been well characterized in terms of genetic alterations or clinical outcomes. Here, through a multi-institutional collaboration, the largest cohort of DIG/DIA to date is examined using advanced laboratory and data processing techniques. Targeted DNA exome sequencing and DNA methylation profiling were performed on tumor specimens obtained from different patients (n = 8) diagnosed histologically as DIG/DIGA. Two of these cases clustered with other tumor entities, and were excluded from analysis. The remaining 16 cases were confirmed to be DIG/DIA by histology and by DNA methylation profiling. Somatic BRAF gene mutations were discovered in 7 instances (43.8%); 4 were BRAFV600E mutations, and 3 were BRAFV600D mutations. Three instances of malignant transformation were found, and sequencing of the recurrence demonstrated a new TP53 mutation in one case, new ATRX deletion in one case, and in the third case, the original tumor harbored an EML4-ALK fusion, also present at recurrence. DIG/DIA are distinct pathologic entities that frequently harbor BRAFV600 mutations. Complete surgical resection is the ideal treatment, and overall prognosis is excellent. While, the small sample size and incomplete surgical records limit a definitive conclusion about the risk of tumor recurrence, the risk appears quite low. In rare cases with wild-type BRAF, malignant progression can be observed, frequently with the acquisition of other genetic alterations.Implications: DIG/DIA are a distinct molecular entity, with a subset frequently harboring either BRAF V600E or BRAF V600D mutations. Mol Cancer Res; 16(10); 1491-8. ©2018 AACR.

Malignant transformation of a desmoplastic infantile ganglioglioma in an infant carrier of a nonsynonymous TP53 mutation

INTRODUCTION

Desmoplastic infantile ganglioglioma is a rare intracranial neoplasm classified as World Health Organization grade I tumor under neuronal and mixed neuronal-glial tumors (2007 World Health Organization brain tumor classification). It is usually a good prognosis, but 40% of patients require further medical, radiation, and/or surgical intervention, and 15% develop leptomeningeal spread or die from desmoplastic infantile ganglioglioma. Transformation to malignant glioblastoma occurs, but the genetic alterations associated with the transformation are generally unknown.

METHODS

We describe a desmoplastic infantile ganglioglioma in a 2-month-old boy, which showed aggressive behavior, requiring debulking at 2.5 months of age and chemotherapy at 10 months of age after tumor progression. At 8.5 years of age he developed malignant transformation to glioblastoma. Chromosome microarray analysis using oligo array and genomic sequencing was performed on the biopsy specimen from 2 months of age and on the subsequent transformed malignant glioblastoma.

RESULTS

After being clinically stable for 7.5-years, transformation to glioblastoma transformation occurred. He did well for 1 year but subsequently died from tumor progression. Chromosome microarray analysis using oligo array performed on the biopsy specimen obtained at 2 months of age did not reveal significant abnormalities; but there were significant genomic deletions and duplications associated with the glioblastoma. These included multiple genomic losses involving 4q and Y, gains of 5q, and amplification of 12q14. Genomic sequencing revealed a single nucleotide variant, p.R248Q in exon 7 of TP53, in the primary desmoplastic infantile ganglioglioma and the glioblastoma multiforme.

CONCLUSIONS

The nonsynonymous variant (p.R248Q in exon 7) of the TP53 gene is predicted to alter the structure of the L2/L3 motif of the DNA binding domain of p53 protein. It was detected in the primary desmoplastic infantile ganglioglioma and glioblastoma multiforme. This child illustrates the rare recurrence of desmoplastic infantile ganglioglioma with malignant transformation to glioblastoma caused by a nonsynonymous TP53 mutation, providing explanation for other rare benign tumor transformations. The TP53 gene is a known primary site of genetic alteration that predisposes to malignant tumors, and this case indicates that it might also be involved in the behavior and outcome of desmoplastic infantile ganglioglioma. Therefore more genetic testing is recommended on desmoplastic infantile ganglioglioma tumors, which may provide biologic prognostic markers.

Desmoplastic infantile ganglioglioma with late presentation. A clinical, radiological and histopathological analysis

Desmoplastic infantile ganglioglioma (DIG) is a rare supratentorial tumor in the central nervous system. Definitive diagnosis of this neoplasm is based on histopathologic analysis evaluating distinctive findings such as the fibroblastic differentiation. Here we present a clinical case of DIG with a long follow-up in an eight-year-old boy with a six-month history of recurrent emesis, psychomotor hyperactivity and generalized tonic-clonic seizures. Computed tomography scan and magnetic resonance imaging (MRI) showed a cystic, heterogeneous, mass on the right temporal uncus. A histopathological diagnosis of late presentation DIG was made. We documented the immunohistochemical expression of a molecular soft tissue / muscle differentiation marker (h-CaD) in addition to a low proliferative index (Ki-67) in this case. After surgical intervention, a control MRI showed changes of right frontal-temporal craniotomy and a persistent mass in the anterior and medial temporal lobe with basal extension. Further surgical intervention was performed, completely removing the tumor, which had the same characteristics. The patient is asymptomatic while receiving anticonvulsant therapy (phenytoin) with no evidence of tumor recurrence on MRI after a follow-up of five years. The low grade and soft tissue appearance in images are correlated with the histopathologic and immunohistochemical profile of this tumor, but the rarity of this tumor makes a presumptive diagnosis by images a challenge. The above-mentioned molecular markers or new ones could be used as molecular targets for molecular imaging studies to increase the probability of a pre-operative diagnosis based on molecular features through images.

Strong desmin expression in a congenital desmoplastic infantile ganglioglioma mimicking pleomorphic rhadomyosarcoma: a case report including ultrastructural and cytogenetic evaluation and review of the literature

PURPOSE

Desmoplastic infantile gangliogliomas (DIGs) are rare tumors of infancy. Herein, we describe an unusual case of DIG diagnosed by prenatal ultrasound.

METHODS

This 5-day-old newborn was delivered after a prenatal ultrasound revealed a large cystic mass in the left cerebral hemisphere along with an echogenic solid component.

RESULTS

The tumor revealed a glial and neuronal proliferation in a background of desmoplasia more typical of DIG and a minor component with a more primitive, immature appearance to the glioneuronal elements. A significant component of the tumor was composed of pleomorphic eosinophilic spindle cells in whorls and interlacing fascicles that showed a strong, sharp, and diffuse positivity for desmin, thus mimicking rhabdomyosarcoma. However, the tumor cells were GFAP (+), INI-1 (+), and myogenin (-). Mitoses were seen both in the more spindle cell astroglial areas as well as the more primitive neuroepithelial cells. The MIB-1 proliferation index was brisk, exceeding 15 %, and in areas it was estimated to be as high as 30 %. Such high proliferation index has been described and accepted in the more primitive neuroepithelial areas, but not in the terminally differentiated, spindle cell astroglial areas as in our case. Our patient was incidentally diagnosed prenatally. To our knowledge, this case is the first documented congenital DIG diagnosed prenatally.

CONCLUSIONS

This case highlights the pitfalls in diagnosing DIG, which can mimic a rhabdomyosarcoma. Furthermore, it underscores the importance of re-evaluating the grading of these tumors or at least segregating the variants where the prognosis may be more guarded.