Diagnostic challenges of neurosarcoidosis in non-endemic areas

Background

Neurosarcoidosis (NS) is a challenging diagnosis, particularly when cases occur in low-prevalence, non-endemic geographic regions. In the United States, the highest incidence is in the Midwest and Northeast, compared to our Southwest location. While it is well known that NS may clinically and neuroradiographically mimic meningeal carcinomatosis, autoimmune or infectious pachymeningitis, neurosyphilis, or tuberculosis, diagnosis may be particularly challenging if systemic signs of sarcoidosis are lacking or unconfirmed or if dural-based masses are present. We reviewed our Colorado experience with NS cases, focusing our study on cases where NS represented the first histological confirmation of disease.

Methods

A search of departmental databases was conducted with the search term "neurosarcoidosis" to identify cases 1-2008 to 12-2019, inclusive of the given case numbers. Patients were only included if their clinical and neuroimaging features were unusual and only when a biopsy of the central nervous system (CNS) represented the first confirmed diagnosis of sarcoidosis.

Results

A total of 17 cases were identified, of which the biopsy of the CNS was used for the initial confirmation of the disease in 9 of them. The most unusual findings were two patients with dural-based masses, one of which had pure NS as the cause of meningioma-like lesions and the second of which had coexistent meningioma and intimately admixed non-necrotizing granulomas of NS.

Conclusion

NS with unusual features, especially in non-endemic areas, continues to yield diagnostic challenges for neurologists, neuroradiologists, and pathologists.

Unusual features of neurosarcoidosis: A 18-year retrospective

BACKGROUND

Neurosarcoidosis (NS) is a challenging diagnosis for clinicians and pathologists. NS most often presents with leptomeningeal involvement where it mimics infectious or neoplastic meningitis, and in up to half of cases, systemic signs of sarcoidosis are lacking. Rare presentations include dural-based mass(es) (mimicking meningioma), hypothalamic/sellar-based lesions (mimicking pituitary adenoma), or as myelopathy (mimicking tumor or neurodegenerative condition). For pathologists, the morphological effects of prior therapy are not well documented. NS as an unsuspected cause of demise today is even less well known.

METHODS

Search of departmental databases and personal files, 2004-2022, for NS cases, with focus on the subset with features of interest to pathologists.

RESULTS

22 cases were identified (8 M: 14F, 13-66 years), in 11 of which the CNS specimen represented first diagnosis of sarcoidosis. 20 were surgical and 2 were autopsy cases. Focus of the study revolved around 2 surgical cases with NS granulomas intimately admixed with tumor (1 meningoma, 1 gonadotroph pituitary adenoma/pituitary neuroendocrine tumor (PitNET). One surgical and one autopsy case each had decrease in lymphocytes and well-formed granulomas, with increased fibrosis and hemosiderin in post-treatment tissues. We speculate, but cannot prove, that this may be due to prior steroid therapy. Both autopsy cases were women (38, 43-years), both with cauda equina syndrome/ progressive weakness as first presentation, and extensive spinal cord/nerve root sarcoidosis at demise. First diagnosis of NS/sarcoidosis was at autopsy in the 38-year-old.

CONCLUSIONS

Unusual features for pathologists are that NS can co-exist within benign tumors, prior therapy alters histological features, and even in the modern era, may be first diagnosed at autopsy.

Double-stranded RNA immunohistochemistry as a screening tool for viral encephalitis

OBJECTIVES

Viral infections of the central nervous system can be challenging to diagnose because of the wide range of causative agents and nonspecific histologic features. We sought to determine whether detection of double-stranded RNA (dsRNA), produced during active RNA and DNA viral infections, could be used to select cases for metagenomic next-generation sequencing (mNGS) from formalin-fixed, paraffin-embedded brain tissue.

METHODS

Eight commercially available anti-dsRNA antibodies were optimized for immunohistochemistry (IHC) and the top antibody tested in a series of cases with confirmed viral infections (n = 34) and cases with inflammatory brain lesions of unclear etiology (n = 62).

RESULTS

Among known positives, anti-dsRNA IHC produced a strong cytoplasmic or nuclear staining pattern for Powassan virus, West Nile virus, rabies virus, JC polyoma virus, and adenovirus while failing to detect Eastern equine encephalitis virus, Jamestown Canyon virus, or any herpesvirus. All the unknown cases were negative by anti-dsRNA IHC, while mNGS detected rare viral reads (0.3-1.3 reads per million total reads) in 2 cases (3%), with only 1 having potential clinical significance.

CONCLUSIONS

Anti-dsRNA IHC can effectively identify a subset of clinically relevant viral infections but not all. The absence of staining should not exclude cases from mNGS if sufficient clinical and histologic suspicion exists.

Genomic and epigenomic re-categorization of congenital glioblastoma and desmoplastic infantile ganglioglioma

INTRODUCTION

The recently updated World Health Organization classification of central nervous system (CNS) tumors, 5th edition, (CNS5) reclassifies pediatric tumors according to their distinct molecular drivers, recognizing a new entity-infant-type hemispheric glioma (IHG). Defined by its unique epigenetic signature, and/or genomic fusions in ALK, ROS1, NTRK, or MET gene, IHG subsumes many cases previously classified as congenital glioblastoma (cGBM). Histologic features of IHG are still poorly defined with known overlap with a clinic radiologically similar entity-desmoplastic infantile ganglioglioma/astrocytoma (DIG).

METHODS

We revisited our cohort of cGBMs and DIGs, now reclassifying them according to CNS5 and compared the clinical, radiologic, molecular and histologic features between the two.

RESULTS

3/6 cases of cGBM that underwent targeted NGS fusion mutation panel were positive for ALK fusions (involving MAP4, MZT2Bex2, and EML4 genes as fusion partners), and 1/6 showed GOPC:ROS1 fusion. Interestingly, GOPC:ROS1 fusion was also shared by 1/5 cases of histologically defined DIG. DNA methylation profiling using the Heidelberg classifier (v12.3) recategorized 2/5 DIG cases as IHG (including the case with ROS1 alteration).

CONCLUSION

In conclusion, histology alone is insufficient to distinguish IHG from DIG, necessitating epigenomic and genomic testing for the diagnosis of early-life gliomas.

Urothelial carcinoma metastases impacting the CNS: A 20-year retrospective series

INTRODUCTION

Our group has a longstanding interest in metastases impacting the central nervous system (CNS), including spread from prostatic adenocarcinomas, thyroid carcinomas, and breast carcinomas, most of which metastasize to CNS sites at a later time after the primary tumor is well-known. However, one of the least frequent types of systemic malignancies to metastasize to brain or spine is urothelial carcinoma. Thus, few large studies from a single institution exist. Fewer still detail the interval between first diagnosis of primary tumor and CNS lesion, or whether a patient might have their first presentation of cancer in the brain or spine, thus prompting review of our 20-year experience.

MATERIALS

Case identification via text word search of pathology databases from our adult and referral hospitals, 2002 to present. Demographic and clinical data were extracted from reports and the medical record.

RESULTS

15 cases, 11 male: 4 female, age range 37-82 years were identified. Nine had metastases to brain parenchyma, 5 to vertebral column impacting spinal cord, and 2 to skull, one of which had tumor extension into right parietal lobe. Strikingly, 5 of 15 patients had had their CNS-impacting metastasis as their first presentation of neoplastic disease.

CONCLUSIONS

CNS metastasis of urothelial carcinoma is a rare occurrence; nevertheless, pathologists should include urothelial carcinoma in their differential diagnosis as a type of cancer that can first present with a CNS-impacting metastasis.

PATH-25. LEPTOMENINGEAL, DURAL, AND EXTRACRANIAL METASTASIS OCCUR IN DIVERSE TYPES OF ADULT HIGH-GRADE GLIOMA

BACKGROUND

Leptomeningeal and extracranial metastases in adult high-grade gliomas are being increasingly recognized as critical issues. Our group has a longstanding interest in this issue, having published multiple examples in 2015 (PMID: 26308254) and 1996 (8617464). We now update our experience, illustrating that dissemination can occur in diverse types of high-grade gliomas, even those with purportedly more favorable prognoses.

METHODS

Search of records, 2018-present, to identify patients with leptomeningeal, dural, and/or extracranial spread clinically recognized prior to patient demise.

RESULTS

Leptomeningeal dissemination was identified in 6 patients: one astrocytoma (frontal lobe, IDH1 R132H+, metastatic to 3-levels spinal cord), a second astrocytoma (frontal lobe, IDH1 R132H+, metastatic to spinal cord with intracranial dissemination), one glioblastoma, small cell type (PIK3CA, CDH1, TP53 mutations, temporal lobe metastatic to cervical cord), one high-grade glioma with piloid features (HGAP, metastatic at presentation; BRAF-mutant, classified by DNA methylation (NIH)) and one high-grade glioma with no match to DNA methylation class (metastatic at presentation, NIH). There were three additional patients: one patient with glioblastoma with FGFR: TACC3 fusion with short-interval dural and cervical lymph node metastases (in Press), one patient with glioblastoma with EGFR amplification and dural invasion and one patient with glioblastoma with massive dural spread and bony invasion at presentation.

CONCLUSION

Although these new 9 individual cases provide no insights into the epidemiology of GBM leptomeningeal, dural and extracranial metastases, our single-institution series, using updated molecular classifications not always available in retrospective studies, shows that dissemination can occur in any, and all, types of adult high-grade gliomas. We put this cohort in perspective with our experience with dissemination in other low and high-grade tumor types: anaplastic myxopapillary ependymomas (30417460), H3 K27M-altered high-grade gliomas (29393845), pineal parenchymal tumors of intermediate differentiation (34418607), myxoid glioneuronal tumor, PDGFRA-mutant (34297434) and spinal cord gangliogliomas (25015869).

Extra-CNS and dural metastases in FGFR3::TACC3 fusion+ adult glioblastoma, IDH-wildtype

BACKGROUND

Adult glioblastomas (GBMs), IDH-wildtype, WHO grade 4 with FGFR3::TACC3 fusion have a better prognosis than standard GBMs. Whether this extended survival leads to late biological consequences is unknown. Although constituting only 4% of all GBMs, FGFR3::TACC3 fusion-positive GBMs manifest recurrent morphological features that allow prediction of this subtype, possibly affecting trial eligibility and/or targeted therapies. However, we have previously shown that an identical histological pattern can be present in wildtype examples, and conversely, occasional FGFR3::TACC3 fusion-positive tumors lack this stereotypic morphology; thus, ultimately molecular characterization is required. We now report for the first time an adult with FGFR3::TACC3 fusion-positive GBM showing archetypal histological features who developed extracranial metastases to provide further insight into potential behavior of the GBM type.

METHODS

Report of a 70-year-old man with left parietal GBM who developed 2 subsequent metastases, all 3 of which were assessed by next-generation sequencing (NGS) and DNA methylation.

RESULTS

Biopsy-proven dural metastases occurred at 8 months and cervical lymph node metastasis at 12-month post-diagnosis before the patient succumbed at 23 months. By NGS, all 3 tumors showed FGFR3::TACC3 fusion as well as an additional PDZD2::TERT fusion of uncertain significance. DNA methylation profiling demonstrated mesenchymal subtype in the initial biopsy and RTKII subtype in subsequent dural and lymph node metastases, indicating intratumor spatial heterogeneity or temporal evolution.

CONCLUSION

Rarely, FGFR3::TACC3 fusion-positive GBM patients may develop dural and extracranial metastatic spread, the latter with subclass switching on epigenomic analysis.

Histopathologic features of nasal glial heterotopia (nasal glioma)

PURPOSE

Nasal glioneuronal heterotopia (NGH) is an uncommon developmental abnormality of the nasal cavity or paranasal soft tissue. Few detailed histologic studies of NGH exist, and molecular analyses have not been performed to date.

METHODS

We describe six cases of pediatric NGH and two representative encephaloceles encountered in our practice over the past 20 years.

RESULTS

Two clinically distinct patient groups were noted, those with 1) intranasal nasal cavity mass (n = 3), or 2) extranasal cutaneous mass on the nose (n = 3, 1 on nasal apex, 2 on nasal bridge). Intranasal cases presented within the first week of life, whereas the extranasal NGH presented at ages of 4, 7, and 8 months. Resection was curative in 5/6 cases, with a single case showing local recurrence. Histologic examination showed a predominantly glial cell composition, with nests of GFAP-immunoreactive neuropil containing large, often multinucleated astrocytes. Neurons, although difficult to identify on H&E-stains, were readily observed in all cases by NeuN-immunostain. At least focal leptomeninges were noted in 2/3 intranasal and 1/3 extranasal NGHs on routine histology, SSTR2A immunohistochemistry further confirmed leptomeninges/ arachnoid cells in 4/6 cases. 1 of 4 NGH (extranasal) cases showed copy number variations in chromosome 16, 17 and 19, which were also present in 1/2 encephalocele cases. The full significance of these alterations remains unknown.

CONCLUSION

We find evidence of histologic overlap between NGH and encephalocele, and, for the first time, report molecular alterations shared between the two entities, suggesting that these conditions may represent spectrum of the same histopathologic entity.

Metastases to the Pituitary Gland: Histological Patterns of Spread and Review of the Literature

Few studies have focused on histological patterns of metastatic spread to the pituitary gland. We review our experience and that in the literature, 1970-present. Departmental cases, 1998-2021, were assessed for anterior versus posterior gland and/or capsular involvement and cohesive tumor obliterating underlying pituitary architecture versus metastatic cells filling pituitary acini with relative acinar preservation. Eleven autopsy/15 surgical cases, including 2 metastases to pituitary adenomas, were identified. Cohesive/obliterative patterns predominated histologically in both surgical and autopsy cases, but acinar filling by metastatic cells was extensive in 3/26 cases, focal in 5/26, and had resulted in initial erroneous impressions of atypical pituitary adenoma/pituitary carcinoma in 1 case and pituitary adenoma with apoplexy in another, likely due to focusing on necrotic areas in the specimen where the acinar pattern had been broken down and not appreciating nearby areas with acinar filling by metastatic cells. Although most pituitary metastases produce readily identifiable cohesive/obliterative patterns, diagnostic challenges remain with the less frequently seen "acinar filling" pattern. A dichotomy exists between patients with symptomatic pituitary metastases occurring early in the disease course and requiring surgical excision versus patients in whom asymptomatic small pituitary metastases are found incidentally at autopsy, the latter almost invariably in late disease stages, with widely disseminated metastatic disease.

Innumerable Meningiomas Arising in a Patient With Tuberous Sclerosis Complex Decades After Radiation Therapy

Meningioma is the most common radiation-induced brain neoplasm, usually occurring after a latency of 20 - 35 years, with multiplicity in 10% of cases. Radiation-induced meningiomas (RIMs) have not previously been reported in patients with tuberous sclerosis complex (TSC), unlike their well-known occurrence in other familial tumor predisposition syndrome patients. We report a TSC patient who developed numerous intracranial meningiomas twenty five year after radiation therapy for subependymal giant cell astrocytoma (SEGA). Autopsy examination showed innumerable, coalescent, benign, meningothelial meningiomas, WHO grade 1, ranging in size from 0.2 cm to 3.3 cm. Autopsy also showed small residual SEGA, radiation-induced cerebral vasculopathy, and classic TSC features including several small subependymal nodules ("candle gutterings"), white matter radial heterotopia, facial angiofibromas, dental enamel pitting, one ash leaf spot, and multiple hepatic and renal angiomyolipomas. Next-generation sequencing analysis utilizing a 500+ gene cancer panel demonstrated chromosomal loss involving the majority of chromosome 22, including the NF2 gene locus, as well as a truncating nonsense mutation in TSC1 p. R509*. While TSC patients rarely require radiation therapy, this striking case suggests that patients with TSC should be monitored closely if cranial therapeutic radiation is administered.

Clinical Features of Pineal Parenchymal Tumors of Intermediate Differentiation (PPTID): A Single-Institution Series

OBJECTIVE

Pineal parenchymal tumors of intermediate differentiation (PPTID) are rare tumors of the pineal gland. Their treatment is often heterogeneous due to the lack of literature to compile standardized treatments. Although no single institution has large numbers of cases, our experience has been that the clinical course is more varied and complicated than reported.

METHODS

We reviewed the clinical data for all patients with pathology found to be consistent with PPTID at our institution between the years 2006 and 2019.

RESULTS

Nine patients were identified. At initial diagnosis, all were treated with surgery and 4 of 9 patients underwent gross total resection. Adjuvant radiation therapy to the resection bed was administered in 6 of 9 patients. Mean follow-up time was 95.3 months. Mean progression-free survival was 50.5 months, with a tendency to be longer for male sex and after gross total resection. Seven patients developed a recurrence. Five of 6 known locations of first recurrences had either distant metastases or dissemination of disease. First recurrences were treated with radiation alone in 5 patients, craniospinal radiation with multiagent chemotherapy in 1 patient, and surgery with radiation therapy in 1. At last follow-up, 2 patients had died.

CONCLUSIONS

Herein, we report clinical patterns of disease progression and treatment patterns of PPTID. Many patients progressed during the follow-up period. Disseminated disease was the most common presentation at recurrence. Ultimately, given the risk of recurrence and dissemination at recurrence, more aggressive treatment strategies should be considered. Specifically, our series suggests a benefit of adjuvant radiation at initial diagnosis for grade II patients.

Secondary parenchymal CNS involvement by lymphoma including rare types: Follicular and EBV-positive NK/T cell lymphoma, nasal type

BACKGROUND

Secondary CNS involvement by systemic lymphomas (SCNSL) is uncommon, but when it occurs, is usually due to diffuse large B cell lymphoma (DLBCL). Three recent unusual cases serve to highlight diagnostic challenges.

OBJECTIVE

To report SCNSL from DLBCL and two unusual lymphoma types: follicular lymphoma with high-grade transformation to DLBCL and NK/T cell lymphoma, nasal type (ENKL), nasal type.

RESULTS

SCNSL in the DLBCL case occurred at 7-year interval from primary in a 54-year-old woman who presented with stroke-like symptoms and a right postcentral gyrus 2.6 × 2.9 × 2.6 cm. mass. The follicular lymphoma occurred at 6-month interval in a 69-year-old woman with 1 month of diplopia and 2 weeks of cognitive decline; multifocal lesions involved temporal lobe, subependymal periventricular areas, brainstem, cerebellum, hypothalamus, corpus callosum and gyrus rectus. The ENKL occurred at 25-month interval from nasal biopsy in a 45-year-old man with 1 week of altered mental status; multifocal cerebral and brainstem lesions were identified. Histological features in cases 1 and 3 were identical to the primary lymphoma, with high-grade transformation to DLBCL in the follicular lymphoma.

CONCLUSION

Unusual features in our series include longer interval from primary to relapse in case 1 with DLBCL (usually <2 years of diagnosis), and SCNSL occurring from either follicular lymphoma or EKNL, nasal type (<6% of cases). Pathologists play an important role in excluding infectious, especially in cases with parenchymal lesions and characterizing the lymphoma type in SCNSL.

LGG-34. CLINICAL AND MOLECULAR CHARACTERIZATION OF A MULTI-INSTITUTIONAL COHORT OF PEDIATRIC SPINAL CORD LOW-GRADE GLIOMAS

BACKGROUND

The MAPK/ERK pathway is involved in cell growth and proliferation, and mutations in the BRAF paralog of this pathway have made it an oncogene of interest in pediatric cancer. Previous studies have identified that BRAF mutations as well as BRAF-KIAA1549 fusions are common in intracranial low-grade gliomas (LGGs). Fewer studies have tested for the presence of these genetic aberrations in spinal LGGs. The aim of this study was to better understand the prevalence of BRAF and other genetic aberrations in spinal LGG.

METHODS

We analyzed 46 spinal LGGs from children age 1–25 years from two institutions, Children’s Hospital Colorado (CHCO) and The Hospital for Sick Children (Sick Kids) for the presence of BRAF fusions or mutations. Data was correlated with clinical information. A 67 gene panel additionally screened for other possible genetic abnormalities of interest in the patient cohort from CHCO. In the Sick Kids cohort, BRAFV600E was tested for by ddPCR and IHC while BRAF fusions where detected by FISH, RT-PCR or Nanostring platform.

RESULTS

Of the 31 patient samples who underwent fusion analysis, 13 (42%) harbored the BRAF-KIAA1549 fusion. Overall survival (OS) for patients confirmed positive for BRAF-KIAA1549 was 100% compared to 76% for fusion negative patients. Other mutations of interest were also identified in this patient cohort including BRAFV600E, STK11, PTPN11, H3F3A, APC, TP53, PIK3CA (polymorphism), FGFR1, and CDKN2A deletion.

CONCLUSION

BRAF-KIAA1549 was seen in higher frequency than BRAFV600E or other genetic aberrations in pediatric spinal LGGs and trends towards longer OS although not statistically significant.

Clinical and molecular characterization of a multi-institutional cohort of pediatric spinal cord low-grade gliomas

Background

The mitogen-activated protein kinases/extracelluar signal-regulated kinases pathway is involved in cell growth and proliferation, and mutations in BRAF have made it an oncogene of interest in pediatric cancer. Previous studies found that BRAF mutations as well as KIAA1549–BRAF fusions are common in intracranial low-grade gliomas (LGGs). Fewer studies have tested for the presence of these genetic changes in spinal LGGs. The aim of this study was to better understand the prevalence of BRAF and other genetic aberrations in spinal LGG.

Methods

We retrospectively analyzed 46 spinal gliomas from patients aged 1–25 years from Children’s Hospital Colorado (CHCO) and The Hospital for Sick Children (SickKids). CHCO utilized a 67-gene panel that assessed BRAF and additionally screened for other possible genetic abnormalities of interest. At SickKids, BRAF^V600E was assessed by droplet digital polymerase chain reaction and immunohistochemistry. BRAF fusions were detected by fluorescence in situ hybridization, reverse transcription polymerase chain reaction, or NanoString platform. Data were correlated with clinical information.

Results

Of 31 samples with complete fusion analysis, 13 (42%) harbored KIAA1549–BRAF. All 13 (100%) patients with confirmed KIAA1549–BRAF survived the entirety of the study period (median [interquartile range] follow-up time: 47 months [27–85 months]) and 15 (83.3%) fusion-negative patients survived (follow-up time: 37.5 months [19.8–69.5 months]). Other mutations of interest were also identified in this patient cohort including BRAF^V600E, PTPN11, H3F3A, TP53, FGFR1, and CDKN2A deletion.

Conclusion

KIAA1549–BRAF was seen in higher frequency than BRAF^V600E or other genetic aberrations in pediatric spinal LGGs and experienced lower death rates compared to KIAA1549–BRAF negative patients, although this was not statistically significant.

Glioblastoma as an autoimmune limbic encephalitis mimic: A case and review of the literature

A 43-year-old woman presented with cognitive decline, focal seizures, brain MRI showing non-enhancing, bilateral hippocampal lesions, but normal cerebrospinal fluid findings, which fulfilled the Graus et al., 2016 criteria for autoimmune limbic encephalitis (ALE). Subjective improvements were observed after immunotherapy. A repeat brain MRI showed new contrast enhancement and positron emission tomography revealed left hippocampal uptake. Biopsy of the right parahippocampus yielded high-grade glioma. Five similar cases, among the 14 with unilateral hippocampal lesions on MRI, were identified in the literature whereby suspected ALE preceded the high-grade glioma diagnosis. Gliomas confined to hippocampi can have clinical features overlapping with ALE.

Targetable molecular alterations in congenital glioblastoma

INTRODUCTION

Congenital glioblastomas (cGBMs) are uncommon tumors presenting in early infancy, variably defined as diagnosed at birth or at age less than 3 months by strict criteria, or more loosely, as occurring in very young children less than 12 months of age. Previous studies have shown that cGBMs are histologically indistinguishable from GBMs in older children or adults, but may have a more favorable clinical outcome, suggesting biological differences between congenital versus other GBMs. Due to the infrequency of cGBMs, especially when employing strict inclusion criteria, molecular features have not been sufficiently explored.

METHODS

Archer FusionPlex Solid Tumor Kit, Archer VariantPlex Solid Tumor Kit, Illumina RNAseq were utilized to study cGBMs seen at our institution since 2002. A strict definition for cGBM was utilized, with only infants less than age 3 months at clinical presentation sought for this study.

RESULTS

Of the 8 cGBM cases identified in our files, 7 had sufficient materials for molecular analyses, and 3 of 7 cases analyzed showed fusions of the ALK gene (involving MAP4, MZT2Bex2 and EML4 genes as fusion partners). One case showed ROS1 fusion. Somatic mutations in TSC22D1, BMG1 and DGCR6 were identified in 1 case. None of the cases showed alterations in IDH1/2, histone genes, or the TERT gene, alterations which can be associated with GBMs in older children or adults.

CONCLUSIONS

Our results show that cGBMs are genetically heterogeneous and biologically different from pediatric and adult GBMs. Identification of ALK and ROS1 raise the possibility of targeted therapy with FDA-approved targeted inhibitors.

PRES: Review of Histological Features

Posterior reversible encephalopathy syndrome was described in 1996 as a clinical-neuroimaging entity characterized by parieto-occipital watershed-region edema without overt infarction. It has been linked to hypertension, eclampsia, immunosuppressive therapies, infections, and autoimmune disorders. The condition usually has an acute onset, presents with seizures, and ameliorates within days. There have been few neuropathological studies, but in some cases, tissue damage may be more permanent.

Neuropathological Findings in a Case of IFIH1-Related Aicardi-Goutières Syndrome

Aicardi-Goutières syndrome (AGS) is a rare syndrome characterized by calcification, diffuse demyelination, and variable degree of brain atrophy. The syndrome is genetically heterogeneous with mutations in 7 genes, including TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR1, and IFIH1 (interferon-induced helicase c domain-containing protein 1) associated with the syndrome, so far. These mutations lead to the overproduction of α-interferon within the central nervous system. Mutations in IFIH1 have been recently described in a subset of AGS, with only 1 previous report of neuropathological findings. We report neuropathological findings in a second case of AGS with a known mutation in IFIH1 gene. The patient is a 16-year-old adolescent boy with early-onset symptoms that progressed to profound loss of cognitive and motor functions. The patient experienced sudden cardiopulmonary arrest at the age of 16 years. At autopsy, the cause of death was determined to be pulmonary thromboembolism. Neuropathological examination revealed microcephaly (brain weight: 916 g) with relatively mild brain atrophy on gross examination. Microscopic examination revealed multifocal calcifications limited to small to medium central nervous system arteries (no evidence of calcification in other organs), involving bilateral cerebral cortex, basal ganglia, thalamus, and cerebellum. Ultrastructural examination showed Calcospherules limited to the vessel walls and the perivasulcar area without evidence of neuronal ferrugination or tubuloreticular bodies. The extent of calcifications was variable across different brain regions, resembling findings in previously reported cases and correlated with the extent of IFIH1 protein expression (data derived from Allen Brain Institute). AGS is a rare cause of brain calcifications that can closely mimic congenital and neonatal infections such as Rubella and similar infections.

Intratumoral heterogeneity of endogenous tumor cell invasive behavior in human glioblastoma

Intratumoral genetic heterogeneity is a widely accepted characteristic of human cancer, including the most common primary malignant brain tumor, glioblastoma. However, the variability in biological behaviors amongst cells within individual tumors is not well described. Invasion into unaffected brain parenchyma is one such behavior, and a leading mechanism of tumor recurrence unaddressed by the current therapeutic armamentarium. Further, providing insight into variability of tumor cell migration within individual tumors may inform discovery of novel anti-invasive therapeutics. In this study, ex vivo organotypic slice cultures from EGFR-wild type and EGFR-amplified patient tumors were treated with the EGFR inhibitor gefitinib to evaluate potential sub-population restricted intratumoral drug-specific responses. High-resolution time-lapse microscopy and quantitative path tracking demonstrated migration of individual cells are punctuated by intermittent bursts of movement. Elevation of population aggregate mean speeds were driven by subpopulations of cells exhibiting frequent high-amplitude bursts, enriched within EGFR-amplified tumors. Treatment with gefitinib specifically targeted high-burst cell subpopulations only in EGFR-amplified tumors, decreasing bursting frequency and amplitude. We provide evidence of intratumoral subpopulations of cells with enhanced migratory behavior in human glioblastoma, selectively targeted via EGFR inhibition. These data justify use of direct human tumor slice cultures to investigate patient-specific therapies designed to limit tumor invasion.

Intracranial Ewing sarcoma: four pediatric examples

BACKGROUND

Ewing sarcoma typically arises in bone and is unrelated to intraparenchymal small blue cell embryonal central nervous system (CNS) tumors previously designated primitive neuroectodermal tumors (PNETs). When the CNS is impacted, it is usually secondary to local extension from either the epidural space, skull, or intracranial or spinal metastases. Primary examples within the cranial vault are rare, usually dural-based, and are largely case reports in the literature. We detail four pediatric patients with solitary, primary intracranial Ewing sarcoma, all manifesting the archetypal EWRS1 gene rearrangement that confirms diagnosis.

PROCEDURE

Neurosurgical Department records, spanning 21 years (1995-2016), were reviewed to identify patients. Demographics, clinical history, pathological/genetic features, and clinical course were retrieved from the medical record and personal files of the authors.

RESULTS

Four patients, one male and three females, age 5 to 16 years, were identified. One presented in extremis from a large lesion, two with soft tissue masses, and the fourth as an incidental finding after being involved in a motor vehicle collision. Three had clear bony involvement: a 10-year-old girl with a large left temporal lesion had clear origin in the skull, with spiculated calcified striations throughout the mass; a 9-year-old girl presented with a bony left petrous apex mass; and a 16-year-old girl presented with a left temporal mass with extension to the dura and underlying bone erosion. Only the 5-year-old boy had a large left frontoparietal mass traversing the falx with no bony contact. All four tumors manifested the diagnostic EWSR1 mutation and were treated with an Ewing sarcoma regimen. Outcomes were variable, with one patient showing progressive metastatic disease and death 3 years after presentation, one patient with disease-free survival 10.5 years after completion of therapy, and one alive and well at the completion of therapy 1 year after diagnosis. One patient completed therapy recently with post-therapy scans showing no evidence of disease.

CONCLUSION

Testing for the EWSR1 mutation confirms the diagnosis of Ewing sarcoma and excludes other types of embryonal CNS tumors. Long-term disease-free survival is possible with adherence to the appropriate therapeutic regimen after gross surgical resection.

p16 Loss and E2F/cell cycle deregulation in infant posterior fossa ependymoma

BACKGROUND

Posterior fossa (PF) ependymomas (EPNs) in infants less than 1 year of age (iEPN-PF) have a poorer clinical outcome than EPNs in older children. While radiation therapy is the standard of care for the latter, it is withheld in infants to avoid neurotoxicity to immature brain. It is unknown whether the adverse outcome in iEPN-PFs is due to treatment differences or aggressive biology. We examined this question using molecular profiling.

METHODS

Six anaplastic iEPN-PFs were subjected to transcriptomic analysis and FISH for p16 loss and gains of 1q, and compared with anaplastic PF EPNs from older children. Results were validated by immunohistochemistry (IHC).

RESULTS

All six iEPN-PFs were grouped within EPN PF subgroup A (PFA). E2F targets and G2M checkpoint were identified as the most enriched gene sets in iEPN-PF, which was validated in a larger independent cohort. Accordingly, MIB-1 IHC demonstrated a higher mitotic rate in iEPN-PFs than noninfant anaplastic EPN PFA. Genetic and protein analyses demonstrated that p16 loss and low p16 protein expression is a hallmark of iEPN-PF, and that none harbored 1q gains. Kaplan-Meier analysis confirmed the poorer clinical outcome of the iEPN-PF cohort.

CONCLUSIONS

Biological differences, characterized by loss of p16 expression without gains of 1q in iEPN-PFs, as well as deregulated E2F target gene transcription, are indicative of deregulated p16-CDK4/6-pRB-E2F pathway activity. This may underlie the poor clinical outcome seen in this group of iEPN-PFs, rather than the withholding of radiation therapy. Results suggest a potential actionable therapy for iEPN-PF, namely cyclin-dependent kinase 4/6 (CDK4/6) inhibitors.

Multinodular and Vacuolating Neuronal Tumor of the Cerebrum: A New "Leave Me Alone" Lesion with a Characteristic Imaging Pattern

Multinodular and vacuolating neuronal tumor of the cerebrum is a recently reported benign, mixed glial neuronal lesion that is included in the 2016 updated World Health Organization classification of brain neoplasms as a unique cytoarchitectural pattern of gangliocytoma. We report 33 cases of presumed multinodular and vacuolating neuronal tumor of the cerebrum that exhibit a remarkably similar pattern of imaging findings consisting of a subcortical cluster of nodular lesions located on the inner surface of an otherwise normal-appearing cortex, principally within the deep cortical ribbon and superficial subcortical white matter, which is hyperintense on FLAIR. Only 4 of our cases are biopsy-proven because most were asymptomatic and incidentally discovered. The remaining were followed for a minimum of 24 months (mean, 3 years) without interval change. We demonstrate that these are benign, nonaggressive lesions that do not require biopsy in asymptomatic patients and behave more like a malformative process than a true neoplasm.

IDH1-Mutation in Diffuse Gliomas in Persons Age 55 Years and Over

Diffuse astrocytoma (DA), anaplastic astrocytoma (AA), and glioblastoma (GBM) are defined by the World Health Organization (WHO) based on IDH-mutational status. The vast majority of IDH-mutated gliomas (90% of which involve a mutation in IDH1 R132H, which can be assessed by IDH1 immunohistochemistry [IHC]) occur in persons younger than 55 years of age. This raises the question as to the prevalence of IDH-mutant tumors in older persons and whether the gliomas in older patients should be routinely tested. Since January 1, 2014, we have employed a standard screening panel for all gliomas regardless of patient age. From 578 total gliomas tested, 88 were IDH-mutant DA/AA/GBMs and 11 IDH-mutant tumors were in persons age 55 and older. Of the 11 IDH-mutant examples in the older group, 9 were first clinical presentations of the tumor, 4 of which were in persons age 70 or older (oldest, 76 years). We assessed whether the typical profile of nuclear ATRX loss with or without strong nuclear p53 IHC occurred in these and younger patients and found that ATRX/p53 IHC patterns paralleled those in younger patients. We conclude that, although infrequent, IDH IHC is strongly recommended for all ages of adult patients with diffuse gliomas.

Desmoplastic infantile astrocytoma/ganglioglioma with rare BRAF V600D mutation

BACKGROUND

Desmoplastic infantile astrocytoma (DIA) and desmoplastic infantile gangliogliomas (DIGs) are rare, massive, cystic and solid tumors of infants usually found in superficial cerebral hemispheres. They manifest prominent desmoplastic stroma, admixed neoplastic astrocytes, primitive-appearing small cells, and additional neoplastic ganglion cells in the case of DIGs. While v-Raf murine sarcoma viral oncogene homolog B (BRAF) mutation is found in up to 50% of pediatric gangliogliomas, two recent studies found that it was rare in DIA/DIGs; we sought to assess BRAF status in DIA/DIGs from our institution.

PROCEDURE

Departmental files from 2000 to 2016 were reviewed to identify cases. Clinical, neuroimaging, histological, and immunohistochemistry (IHC) features were assessed; the latter included IHC for astrocytic and neuronal markers and BRAF VE1. BRAF mutational assessment by Sanger and next-generation sequencing was attempted in all cases.

RESULTS

All six identified cases (four males-two females; three DIA-three DIG) occurred in children <1-year old, were large, cerebral-hemispheric, cystic and solid, and enhancing tumors. Only one case, a DIG with prominent aggregates of neoplastic ganglion cells, showed either BRAF VE1 IHC positivity or mutation by Sanger and next-generation sequencing (rare c. 1799_1800delinsAT; p. V600D). Four of six archival cases were BRAF VE1 IHC negative, but failed mutational sequencing.

CONCLUSION

Five of six classic DIA/DIGs were negative for BRAF mutation; previous series have identified BRAF mutation in two of 18 and one of 14 cases, although all were the more common BRAF V600E. We were unable to find other examples of glial tumors in public databases with this rare BRAF V600D mutation. Identification of BRAF mutational opens the possibility of BRAF-targeted therapies for the subset of DIA/DIG that clinically progress postresection.

Elucidating the Role of the Desmosome Protein p53 Apoptosis Effector Related to PMP-22 in Growth Hormone Tumors

Densely granulated and sparsely granulated (SG) growth hormone (GH) pituitary adenomas differ in biological behavior, which may be correlated with their known differences in cytoplasmic keratin distribution and E-cadherin expression. We wanted to explore candidate genes that might further explain this behavior. Exon expression microarray was performed on 21 GH tumors (10 SG and 11 densely granulated) and 20 normal control pituitaries from autopsy. Bioinformatic analyses confirmed a differential molecular signature between normal pituitary and GH tumors as well as between the GH tumor subtypes. There was a consistent downregulation of transcripts involved in the structure and function of the desmosome, including desmoplakin (eightfold), desmoglein 2 (sixfold), plakophilin 2 (sevenfold), and p53 apoptosis effector related to PMP-22 (PERP; sixfold) in SG tumors compared with normal pituitary. PERP is lost in more aggressive SG human GH pituitary tumors. PERP re-expression in GH3 rat GH tumor cells resulted in decreased colony formation compared with vector transfectants, confirming the role of PERP as a tumor suppressor with no effects on proliferation. Increased PERP expression was associated with loss of a survival advantage in a hypoxic environment, as assessed by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (P < 0.05) and cleaved caspase-3 (P < 0.05). Downregulation of desmosomal formation transcripts including PERP may contribute to the aggressive phenotype seen in SG GH pituitary tumors and their behavior in response to surgery and medical therapy.

Review of xanthomatous lesions of the sella

Xanthomatous lesions of the sellar region have traditionally been divided into two separate categories, xanthomatous hypophysitis (XH) and xanthogranuloma (XG) of the sellar region. The seminal article on XH, a condition typified by foamy histiocytes and lymphoplasmacytic infiltrates in the pituitary gland/sellar region, but usually little or no hemosiderin pigment, detailed three patients. However, most reports since that time have been single cases, making understanding of the entity difficult. In contrast, the seminal report on XG, characterized by sellar region cholesterol clefts, lymphoplasmacytic infiltrates, marked hemosiderin deposits, fibrosis, multinucleated giant cells around cholesterol clefts, eosinophilic granular necrotic debris, and accumulation of macrophages, included 37 patients, allowing more insights into etiology. Few examples could be linked to adamantinomatous craniopharyngioma, and although ciliated epithelium similar to that of Rathke cleft cyst (RCC) was identified up to 35% of the 37 cases, it could not be proven that XG was related to hemorrhage into RCC. Case reports since that time, however, occasionally linked XG to RCC when an etiology could be identified at all, and a few recognized that a spectrum exists in xanthomatous lesions of the sella. They review literature, adding 23 cases from our own experience, to confirm that overlap occurs between XH and XG, and that the majority-but not all-can be linked to RCC leakage/rupture/hemorrhage. It was suggested that progressive accumulation of hemosiderin pigment in the lesion, possibly caused by the multiple episodes of bleeding, could account for the transition of at least some cases of XH to XG.

Autophagy inhibition overcomes multiple mechanisms of resistance to BRAF inhibition in brain tumors

Kinase inhibitors are effective cancer therapies, but tumors frequently develop resistance. Current strategies to circumvent resistance target the same or parallel pathways. We report here that targeting a completely different process, autophagy, can overcome multiple BRAF inhibitor resistance mechanisms in brain tumors. BRAF^V600Emutations occur in many pediatric brain tumors. We previously reported that these tumors are autophagy-dependent and a patient was successfully treated with the autophagy inhibitor chloroquine after failure of the BRAF^V600E inhibitor vemurafenib, suggesting autophagy inhibition overcame the kinase inhibitor resistance. We tested this hypothesis in vemurafenib-resistant brain tumors. Genetic and pharmacological autophagy inhibition overcame molecularly distinct resistance mechanisms, inhibited tumor cell growth, and increased cell death. Patients with resistance had favorable clinical responses when chloroquine was added to vemurafenib. This provides a fundamentally different strategy to circumvent multiple mechanisms of kinase inhibitor resistance that could be rapidly tested in clinical trials in patients with BRAF^V600E brain tumors.

DOI:http://dx.doi.org/10.7554/eLife.19671.001

Cancers of the brain and spine are the second most common kind of tumor in children, after cancers of the blood and bone marrow. Yet brain and spine tumors kill more children than any other cancer, in part because many become resistant to treatment.

Like in other cancers, cells in brain and spine tumors often use a process called autophagy to survive the treatments that are used to try and kill them. This process allows cells to recycle proteins and other things inside the cell and use them for energy when the cell is under stress. In 2014, researchers reported that brain tumors carrying a mutation called BRAF^V600E rely on autophagy to survive treatment with medications that target this mutation. These findings suggested that blocking autophagy might make the medications more effective against BRAF^V600Emutant tumors and overcome the resistance.

Now, Mulcahy Levy et al. – who include most of the researchers involved in the 2014 study – report that blocking autophagy does indeed overcome this kind of resistance in multiple types of tumor. The experiments made use of human brain tumor cells that can be grown in the laboratory and have been widely studied, as well as samples collected from patients.

Mulcahy Levy et al. were able to block autophagy in the tumor cells by using genetic methods and, importantly, by using an approved and inexpensive drug that could be rapidly translated into clinical trials. Together these findings suggest that blocking autophagy in patients might be a safe and effective strategy to improve their response to existing therapies that target the BRAF^V600E mutation. Future clinical trials are now needed to test more patients and verify if this treatment plan can be broadly effective in patients with these types of brain cancers.

DOI:http://dx.doi.org/10.7554/eLife.19671.002

Double separate versus contiguous pituitary adenomas: MRI features and endocrinological follow up

PURPOSE

Double pituitary adenomas are defined as two adenomas within a gland. These have distinct light microscopic and immunohistochemical features and may be clearly-separate or contiguous. Most reports have focused on the various hormonal combinations in double tumors rather than on any potential increased risk for residual mass or endocrinopathy.

METHODS

Departmental files were searched to identify all double adenomas from 1/1/2000 to 3/1/2016, with review of magnetic resonance imaging (MRI) to determine if the dual nature of the lesions could be discerned retrospectively after histologic diagnosis of double adenoma. All cases were immunostained for standard anterior pituitary hormones.

RESULTS

Eight cases were identified: 2 follicle-stimulating hormone (FSH)/alpha subunit (ASU) + prolactinoma (PRL); 1 PRL + corticotroph (ACTH); 1 hormone-negative + PRL; 1 ACTH + ASU/growth hormone (GH)/PRL; 1 GH/PR + PRL; 1 FSH/ASU, + ACTH; 1 GH + luteinizing hormone (LH). One patient had clearly-separate lesions identified preoperatively and required two surgical procedures for gross total resection. A second patient had 2 lesions recognized at surgery and afterwards on retrospective neuroimaging. The remaining 6 patients had double adenomas discovered at the time of histologic examination that were not resolvable at surgery or on retrospective neuroimaging. Four patients, 2 with clearly-separate and 2 with contiguous double adenomas, had persistent MRI abnormalities, and one had continued endocrine abnormalities.

CONCLUSIONS

Double contiguous pituitary adenomas are difficult to anticipate preoperatively or to resolve intraoperatively. Although double contiguous adenomas are much more common than double separate lesions, both have a risk for subtotal resection and, thus, residual mass and/or endocrinopathy may ensue.

SOX10 Distinguishes Pilocytic and Pilomyxoid Astrocytomas From Ependymomas but Shows No Differences in Expression Level in Ependymomas From Infants Versus Older Children or Among Molecular Subgroups

SOX10 is important in nonneoplastic oligodendroglial development, but mRNA transcripts and protein expression are identified in a wider variety of CNS glial neoplasms than oligodendrogliomas. We previously demonstrated high levels of SOX10 mRNA and protein in pilocytic astrocytomas (PAs) but not ependymomas (EPNs). We now extend these studies to investigate subsets of these 2 tumors that affect infants, pilomyxoid astrocytomas (PMAs) and infant (<1 year) ependymomas (iEPNs). By gene expression microarray analysis, we found that iEPNs and all EPNs in older children showed very low SOX10 expression levels, on average 7.1-fold below normal control tissues. EPN groups showed no significant difference in SOX10 expression between iEPN and EPN. PAs/PMAs had 24.1/29.4-fold higher transcript levels, respectively, than those in normal tissues. Using immunohistochemical analysis of adult, pediatric, and infantile EPNs and of PAs/PMAs, we found that EPNs from multiple anatomical locations and both age groups (n = 228) never showed 3+ diffuse nuclear immunostaining for SOX10; the majority were scored at 0 or 1+. Conversely, almost all pediatric and adult PAs and PMAs (n = 47) were scored as 3+. These results suggest that in select settings, SOX10 immunohistochemistry can supplement the diagnosis of PMA and PA and aid in distinguishing them from EPNs.

Differential somatostatin receptor (SSTR) 1-5 expression and downstream effectors in histologic subtypes of growth hormone pituitary tumors

PURPOSE

The aim of this study was to examine whether differential expression of somatostatin receptors (SSTR) 1-5 and downstream effectors are different in densely (DG) and sparsely (SG) granulated histological growth hormone (GH) pituitary tumor subtypes.

METHODS

The study included 33 acromegalic patients with 23 DG and 10 SG tumors. SSTR1-5 were measured by qPCR and immunoblotting. Signaling candidates downstream of SSTR2 were also assessed.

RESULTS

SSTR2 mRNA and protein levels were significantly higher in DG compared to SG tumors. Downstream of SSTR2, p27(kip1) was decreased (2.6-fold) in SG compared to DG tumors, suggesting a potential mechanism of SSA resistance in SG tumors with intact SSTR2 expression. Re-expression of E-cadherin in GH pituitary cell increased p27(kip1) levels.

CONCLUSIONS

Histological subtyping correlated with SSTR2, E cadherin and p27(kip) protein levels and these may serve as useful biomarkers in GH tumors to predict behavior and response to therapy with SSA.

Dual use of E-cadherin and D2-40 immunostaining in unusual meningioma subtypes

OBJECTIVES

Meningiomas usually can be readily diagnosed on H&E alone, although occasionally immunohistochemistry (IHC) confirmation is desirable. Studies exploring the diagnostic utility of either podoplanin (D2-40) or E-cadherin IHC in meningiomas have conflicted, and no studies exist in which the two IHCs have been used in combination for diagnosis.

METHODS

E-cadherin and D2-40 IHC was performed on 77 meningiomas (31 ordinary; eight microcystic; four rare myxoid; six metaplastic; six invasive of orbit, muscle, and/or soft tissue; two metastatic; six brain-invasive World Health Organization [WHO] grade II, nine non-brain-invasive WHO grade II; and five anaplastic WHO grade III), with semi-quantitative scoring on a three-tier scale (0, focal [1+], strong/diffuse [2+]).

RESULTS

All meningiomas were either E-cadherin or D2-40 IHC+, with 69 of 77 showing dual immunostaining, most at the 2+ level. No downregulation of E-cadherin IHC was found in invasive or high-grade meningiomas.

CONCLUSIONS

Dual E-cadherin/D2-40 IHC can supplement diagnosis of meningioma.

Identification of targets for rational pharmacological therapy in childhood craniopharyngioma

Introduction

Pediatric adamantinomatous craniopharyngioma (ACP) is a histologically benign but clinically aggressive brain tumor that arises from the sellar/suprasellar region. Despite a high survival rate with current surgical and radiation therapy (75–95 % at 10 years), ACP is associated with debilitating visual, endocrine, neurocognitive and psychological morbidity, resulting in excheptionally poor quality of life for survivors. Identification of an effective pharmacological therapy could drastically decrease morbidity and improve long term outcomes for children with ACP.

Results

Using mRNA microarray gene expression analysis of 15 ACP patient samples, we have found several pharmaceutical targets that are significantly and consistently overexpressed in our panel of ACP relative to other pediatric brain tumors, pituitary tumors, normal pituitary and normal brain tissue. Among the most highly expressed are several targets of the kinase inhibitor dasatinib – LCK, EPHA2 and SRC; EGFR pathway targets – AREG, EGFR and ERBB3; and other potentially actionable cancer targets – SHH, MMP9 and MMP12. We confirm by western blot that a subset of these targets is highly expressed in ACP primary tumor samples.

Conclusions

We report here the first published transcriptome for ACP and the identification of targets for rational therapy. Experimental drugs targeting each of these gene products are currently being tested clinically and pre-clinically for the treatment of other tumor types. This study provides a rationale for further pre-clinical and clinical studies of novel pharmacological treatments for ACP. Development of mouse and cell culture models for ACP will further enable the translation of these targets from the lab to the clinic, potentially ushering in a new era in the treatment of ACP.

Growth hormone tumor histological subtypes predict response to surgical and medical therapy

Growth hormone (GH) pituitary tumors are associated with significant morbidity and mortality. Current treatments, including surgery and medical therapy with somatostatin analogs (SSA), dopamine agonists and/or a GH receptor antagonist, result in disease remission in approximately half of patients. Predictors of GH tumor response to different therapies have been incompletely defined based on histologic subtype, particularly densely (DG) versus sparsely (SG) granulated adenomas. The aim of this study was to examine our own institutional experience with GH adenomas and correlate how subtype related to clinical parameters as well as response to surgery and medical therapies. A retrospective chart review of 101 acromegalic patients operated by a single neurosurgeon was performed. Clinical data were correlated with histologic subtype and disease control, as defined by IGF-1 levels, and random growth hormone levels in response to surgery and/or medical therapies. SG tumors, compared to DG, occurred in younger patients (p = 0.0010), were 3-fold larger (p = 0.0030) but showed no differences in tumor-invasion characteristics (p = 0.12). DG tumors had a higher rate of remission in response to surgery compared to SG, 65.7 vs. 14.3 % (p < 0.0001), as well as to medical therapy with SSAs (68.8 % for DG vs. 28.6 % for SG tumors; p = 0.028). SG tumors not controlled with SSAs consistently responded to a switch to, or addition of, a GH receptor antagonist. Histological GH tumor subtyping implicates a different clinical phenotype and biologic behavior, and provides prognostic significance for surgical success and response to medical therapies.

An Algorithmic Approach to Sellar Region Masses

Context

Most sellar region masses (85%–90%) are pituitary adenomas; however, other neoplasms or even inflammatory or cystic nonneoplastic lesions may occasionally be encountered in this location. A practical, non–electron-microscopically based approach is essential for the daily practice of diagnosing and subclassifying adenomatous and nonadenomatous sellar region lesions.

Objective

To provide an algorithmic approach to sellar region masses for the pathologist and to formulate a cost-effective, limited panel of stains and immunostains that can be used in daily practice at most small to medium-sized centers.

Design

Pool collective experience of 3 neuropathologists practicing at academic medical centers with expertise in diagnosis and treatment of sellar region masses to craft a single-page algorithmic diagram and to liberally illustrate the range of lesions present in the sellar region.

Results

After formulating a differential diagnosis, the general pathologist can generate a confident final diagnosis of adenoma using 1 histochemical (reticulin) and 1 immunohistochemical (synaptophysin) stain, supplemented by 5 immunohistochemical stains (CAM5.2, follicle-stimulating hormone, growth hormone, prolactin, and adrenocorticotropic hormone), which provide subtyping of the adenoma in the overwhelming majority of examples. CAM5.2 and clinical information further help identify clinically aggressive variants such as sparsely granulated growth hormone adenomas and silent adrenocorticotropic hormone adenomas, respectively. MIB-1, thyroid transcription factor 1, and S-100 protein can be of further assistance in select cases where increased mitotic activity or possible nonadenomatous spindle cell lesions are suspected.

Conclusions

Adenomas, normal anterior or posterior gland, and nonadenomatous masses can be easily diagnosed in a nontertiary pathology laboratory setting.

Massive dissemination from spinal cord gangliogliomas negative for BRAF V600E: report of two rare adult cases

OBJECTIVES

Metastatic leptomeningeal spread from spinal cord gangliogliomas (GGs) is exceedingly rare.

METHODS

Two adult women, aged 27 and 51 years, died of massive disseminations of cervicothoracic GGs 4 and 6 years, respectively, after initial diagnoses; full autopsies were performed. BRAF status was assessed by VE1 immunohistochemistry (IHC), Sanger sequencing, and a single-nucleotide base extension assay (SNaPshot, Applied Biosystems, Princeton, NJ).

RESULTS

The 27-year-old underwent two biopsies, chemotherapy, radiation, and ventriculoperitoneal shunt placement; she developed craniospinal and peritoneal dissemination. Autopsy confirmed shunt-mediated peritoneal metastases, microscopic bone marrow involvement, and profuse spinal and supratentorial leptomeningeal and parenchymal spread. The 51-year-old underwent two resections, radiation, and chemotherapy and developed pancytopenia with biopsy-proven bony metastases 15 months before death. Autopsy demonstrated leptomeningeal, subpial, and subependymal metastases. The tumors in both primary and metastatic sites were BRAF negative by VE1 IHC and two different mutational analyses. This compared with negative BRAF results for an additional four nonmetastatic adult nonsupratentorial GGs and in our study.

CONCLUSIONS

We document two rare cases of massively metastatic spinal cord GGs in adult patients who were negative for BRAF V600E mutations via multiple methods.

Pediatric rhabdoid tumors of kidney and brain show many differences in gene expression but share dysregulation of cell cycle and epigenetic effector genes

BACKGROUND

Rhabdoid tumors (RTs) are aggressive tumors of early childhood that occur most often in brain (AT/RTs) or kidney (KRTs). Regardless of location, they are characterized by loss of functional SMARCB1 protein, a component of the SWI/SNF chromatin remodeling complex. The aim of this study was to determine genes and biological process dysregulated in common to both AT/RTs and KRTs.

PROCEDURE

Gene expression for AT/RTs was compared to that of other brain tumors and normal brain using microarray data from our lab. Similar analysis was performed for KRTs and other kidney tumors and normal kidney using data from GEO. Dysregulated genes common to both analyses were analyzed for functional significance.

RESULTS

Unsupervised hierarchical clustering of RTs identified three major subsets: two comprised of AT/RTs, and one of KRTs. Compared to other tumors, 1,187, 663, and 539 genes were dysregulated in each subset, respectively. Only 14 dysregulated genes were common to all three subsets. Compared to normal tissue, 5,209, 4,275, and 2,841 genes were dysregulated in each subset, with an overlap of 610 dysregulated genes. Among these genes, processes associated with cell proliferation, MYC activation, and epigenetic dysregulation were common to all three RT subsets.

CONCLUSIONS

The low overlap of dysregulated genes in AT/RTs and KRTs suggests that factors in addition to SMARCB1 loss play a role in determining subsequent gene expression. Drugs which target cell cycle or epigenetic genes may be useful in all RTs. Additionally, targeted therapies tailored to specific RT subset molecular profiles should be considered.

76-year-old man with a cerebellar lesion

We report a case of balloon cell melanoma metastatic to the cerebellum; the clear cell morphology prompted initial differential diagnostic considerations of metastatic renal cell carcinoma and hemangioblastoma in this site. To our knowledge this is only the second case of metastatic balloon cell melanoma to the CNS.