Enhancing mitosis quantification and detection in meningiomas with computational digital pathology.

Mitosis is a critical criterion for meningioma grading. However, pathologists' assessment of mitoses is subject to significant inter-observer variation due to challenges in locating mitosis hotspots and accurately detecting mitotic figures. To address this issue, we leverage digital pathology and propose a computational strategy to enhance pathologists' mitosis assessment. The strategy has two components: (1) A depth-first search algorithm that quantifies the mathematically maximum mitotic count in 10 consecutive high-power fields, which can enhance the preciseness, especially in cases with borderline mitotic count. (2) Implementing a collaborative sphere to group a set of pathologists to detect mitoses under each high-power field, which can mitigate subjective random errors in mitosis detection originating from individual detection errors. By depth-first search algorithm (1) , we analyzed 19 meningioma slides and discovered that the proposed algorithm upgraded two borderline cases verified at consensus conferences. This improvement is attributed to the algorithm's ability to quantify the mitotic count more comprehensively compared to other conventional methods of counting mitoses. In implementing a collaborative sphere (2) , we evaluated the correctness of mitosis detection from grouped pathologists and/or pathology residents, where each member of the group annotated a set of 48 high-power field images for mitotic figures independently. We report that groups with sizes of three can achieve an average precision of 0.897 and sensitivity of 0.699 in mitosis detection, which is higher than an average pathologist in this study (precision: 0.750, sensitivity: 0.667). The proposed computational strategy can be integrated with artificial intelligence workflow, which envisions the future of achieving a rapid and robust mitosis assessment by interactive assisting algorithms that can ultimately benefit patient management.

Small pretreatment lesion size and high sphericity as favorable prognostic factors after laser interstitial thermal therapy in brain metastases.

OBJECTIVE: The objective of this study was to identify baseline clinical and radiological characteristics of brain metastases (BMs) associated with a higher probability of lesion-specific progression-free survival (PFS-L) after laser interstitial thermal therapy (LITT). METHODS: A total of 47 lesions in 42 patients with BMs treated with LITT were retrospectively examined, including newly diagnosed BM, suspected recurrent BM, and suspected radiation necrosis. The association of baseline clinical and radiological features with PFS-L was assessed using survival analyses. Radiological features included lesion size measurements, diffusion and perfusion metrics, and sphericity, which is a radiomic feature ranging from 1 (perfect sphere) to 0. RESULTS: The probability of PFS-L for the entire cohort was 88.0% at 3 months, 70.6% at 6 months, 67.4% at 1 and 2 years, and 62.2% at 3 years. For lesions progressing after LITT (n = 13), the median time to progression was 3.9 months, and most lesions (n = 11) progressed within 6 months after LITT. In lesions showing response to LITT (n = 17), the median time to response was 12.1 months. All 3 newly diagnosed BMs showed a long-term response. The mean (± SD) follow-up duration for all censored lesions (n = 34) was 20.7 ± 19.4 months (range 12 days to 6.1 years). The mean pretreatment enhancing volume was 2.68 cm3 and the mean sphericity was 0.70. Pretreatment small enhancing volume (p = 0.003) and high sphericity (p = 0.024) computed from lesion segmentation predicted a longer PFS-L after LITT. Lesions meeting optimal cutoffs of either enhancing volume < 2.5 cm3 (adjusted p = 0.004) or sphericity ≥ 0.705 (adjusted p = 0.019) had longer PFS-L, and their probability of PFS-L was 86.8% at 3 years. Lesions meeting both cutoffs showed a cumulative benefit (p < 0.0001), with a 100% probability of PFS-L at 3 years, which was unchanged at the end of follow-up (4.1 years). Manually computed estimates of lesion size (maximal axial diameter, p = 0.011) and sphericity (p = 0.043) were also predictors of PFS-L. Optimal cutoffs of diameter < 2 cm (adjusted p = 0.035) or manual sphericity ≥ 0.91 (adjusted p = 0.092) identified lesions with longer PFS-L, and lesions meeting both cutoffs showed a cumulative benefit (p = 0.0023). Baseline diffusion imaging did not predict PFS-L. A subset of lesions (n = 7) with highly perfused hotspots had worse PFS-L (adjusted p = 0.010), but perfusion signal contamination from vessels and cortex and underlying size differences were possible confounders. CONCLUSIONS: Small size and high sphericity are ideal baseline features for lesions considered for LITT treatment, with a cumulative PFS-L benefit when both features are present, that could aid patient selection.

SREBP-1 upregulates lipophagy to maintain cholesterol homeostasis in brain tumor cells.

Cholesterol is a structural component of cell membranes. How rapidly growing tumor cells maintain membrane cholesterol homeostasis is poorly understood. Here, we found that glioblastoma (GBM), the most lethal brain tumor, maintains normal levels of membrane cholesterol but with an abundant presence of cholesteryl esters (CEs) in its lipid droplets (LDs). Mechanistically, SREBP-1 (sterol regulatory element-binding protein 1), a master transcription factor that is activated upon cholesterol depletion, upregulates critical autophagic genes, including ATG9B, ATG4A, and LC3B, as well as lysosome cholesterol transporter NPC2. This upregulation promotes LD lipophagy, resulting in the hydrolysis of CEs and the liberation of cholesterol from the lysosomes, thus maintaining plasma membrane cholesterol homeostasis. When this pathway is blocked, GBM cells become quite sensitive to cholesterol deficiency with poor growth in vitro. Our study unravels an SREBP-1-autophagy-LD-CE hydrolysis pathway that plays an important role in maintaining membrane cholesterol homeostasis while providing a potential therapeutic avenue for GBM.

Hyaline protoplasmic astrocytopathy in epilepsy.

Hyaline protoplasmic astrocytopathy (HPA) describes a rare histologic finding of eosinophilic, hyaline cytoplasmic inclusions in astrocytes, predominantly in the cerebral cortex. It has mainly been observed in children and adults with a history of developmental delay and epilepsy, frequently with focal cortical dysplasia (FCD), but the nature and significance of these inclusions are unclear. In this study, we review the clinical and pathologic features of HPA and characterize the inclusions and brain tissue in which they are seen in surgical resection specimens from five patients with intractable epilepsy and HPA compared to five patients with intractable epilepsy without HPA using immunohistochemistry for filamin A, previously shown to label these inclusions, and a variety of astrocytic markers including aldehyde dehydrogenase 1 family member L1 (ALDH1L1), SRY-Box Transcription Factor 9 (SOX9), and glutamate transporter 1/excitatory amino acid transporter 2 (GLT-1/EAAT2) proteins. The inclusions were positive for ALDH1L1 with increased ALDH1L1 expression in areas of gliosis. SOX9 was also positive in the inclusions, although to a lesser intensity than the astrocyte nuclei. Filamin A labeled the inclusions but also labeled reactive astrocytes in a subset of patients. The immunoreactivity of the inclusions for various astrocytic markers and filamin A as well as the positivity of filamin A in reactive astrocytes raise the possibility that these astrocytic inclusions may be the result of an uncommon reactive or degenerative phenomenon.

Upper lumbar spine far lateral disc herniations masquerading as peripheral nerve sheath tumors: illustrative cases.

BACKGROUND: Migratory disc herniations can mimic neoplasms clinically and on imaging. Far lateral lumbar disc herniations usually compress the exiting nerve root and can be challenging to distinguish from a nerve sheath tumor due to the proximity of the nerve and characteristics on magnetic resonance imaging (MRI). These lesions can occasionally present in the upper lumbar spine region at the L1-2 and L2-3 levels. OBSERVATIONS: The authors describe 2 extraforaminal lesions in the far lateral space at the L1-2 and L2-3 levels, respectively. On MRI, both lesions tracked along the corresponding exiting nerve roots with avid postcontrast rim enhancement and edema in the adjacent muscle tissue. Thus, they were initially concerning for peripheral nerve sheath tumors. One patient underwent fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) screening and demonstrated moderate FDG uptake on PET-CT scan. In both cases, intraoperative and postoperative pathology revealed fibrocartilage disc fragments. LESSONS: Differential diagnosis for lumbar far lateral lesions that are peripherally enhancing on MRI should include migratory disc herniation, regardless of the level of the disc herniations. Accurate preoperative diagnosis can aid in decision making for management, surgical approach, and resection.

Low-grade B-cell lymphoma of the central nervous system with plasmacytic differentiation and amyloid deposition.

A 65-year-old woman with a resolved history of epilepsy due to a motor vehicle accident and hippocampal sclerosis presented with recurrent de novo seizures. Brain imaging demonstrated enhancement in the left parieto-occipital lobe. At histopathological examination, the lesion displayed a diffuse lymphoid infiltrate comprised of small atypical lymphocytes, plasmacytoid lymphocytes, and scattered plasma cells with amyloid deposition. Pathology workup demonstrated a monotypic B-cell phenotype of the lymphoid infiltrate, expressing lambda light chain restriction and plasmacytic differentiation without MYD88 mutations. The patient had no systemic evidence of lymphoma, plasma cell dyscrasia, or amyloidosis. A diagnosis of low-grade B-cell lymphoma of the central nervous system with plasmacytic differentiation and amyloid deposition was made.

Isocitrate Dehydrogenase Mutations Are Associated with Different Expression and DNA Methylation Patterns of OLIG2 in Adult Gliomas.

Isocitrate dehydrogenase (IDH) mutant gliomas are associated with a better prognosis in comparison to adult IDH wild-type glioma and glioma-CpG island methylator phenotypes. Although OLIG2 is mainly expressed in oligodendrocytes in normal adult brain, it is expressed in both astrocytomas and oligodendrogliomas. Utilizing the clinical, DNA methylation, and RNA-sequencing data from the Cancer Genome Atlas (TCGA) for lower-grade glioma and glioblastoma cohorts, we explored the association between IDH mutation status and OLIG2 expression on transcription, DNA methylation, and gene target levels. Compared to IDH wild-type gliomas, IDH mutant gliomas showed consistently higher expression of OLIG2 transcripts. OLIG2 overexpression is a good surrogate marker for IDH mutation with an AUC of 0.90. At the DNA methylation level, IDH-mutant gliomas showed hyper- and hypomethylation foci upstream of the OLIG2 transcription start site. Underexpressed OLIG2 target genes in IDH mutant glioma were enriched in cell cycle-related pathways. Thus, the differential expression of OLIG2 between IDH mutant and wild-type gliomas reflects involvement in multiple pathways in tumorigenesis.

Central nervous system ALK-negative anaplastic large cell lymphoma with IRF4/DUSP22 rearrangement.

Anaplastic large cell lymphomas (ALCL) are mature T-cell neoplasms, approximately half of which harbor rearrangements of the ALK gene that confer a good prognosis. Recent studies have demonstrated that a significant proportion of ALK-negative ALCLs demonstrate rearrangements of the IRF4/DUSP22 locus that also are typically associated with a favorable prognosis. ALCL with primary involvement of the central nervous system (CNS) is extremely rare. We report what may be the first case of ALK-negative ALCL with IRF4/DUSP22 rearrangement involving the brain in a 55-year-old man. Magnetic resonance imaging demonstrated signal abnormalities in the periventricular region, corpus callosum and cingulate gyrus. Biopsy revealed a diffuse parenchymal and angiocentric infiltrate of CD30-positive cells that showed IRF4/DUSP22 rearrangement by fluorescence in situ hybridization. We also review the clinical and pathologic features of primary CNS ALK-negative ALCLs in the literature and highlight the need for awareness of this entity to optimize appropriate management.

Neuropathologic Findings in Chronic Kidney Disease (CKD).

Studying the neuropathologic autopsy findings in subjects with chronic kidney disease (CKD) or chronic renal failure (CRF) is difficult for several reasons: etiology of the CKD may be heterogeneous, affected patients may have one or more major co-morbidities that themselves can cause significant neurologic disease, and agonal events may result in significant findings that were of minimal significance earlier in a patient's life. We studied the constellation of neuropathologic abnormalities in 40 autopsy brains originating from subjects of ages 34-95 years (no children in the study). The most common pathologic change was that of ischemic infarcts (cystic, lacunar and/or microinfarcts), which were seen in over half of subjects. These were associated with both large artery atherosclerosis and arteriolosclerosis (A/S), the latter finding being present in 29/40 subjects. Charcot-Bouchard microaneurysms were present in the brains of three subjects, in one case associated with severe amyloid angiopathy. Microvascular calcinosis (medial sclerosis in the case of arterioles) was seen in the basal ganglia (n=8) and/or endplate region of the hippocampus (n=7) and occasional ischemic infarcts in one brain showed severe calcification. Sequelae of cerebrovascular disease (especially A/S or microvascular disease) are a common neuropathologic substrate for neurologic disability and brain lesions in this complex group of patients. Regulation of calcium metabolism within brain microvessel walls may be worthy of further research in both human brain specimens and animal models.

Intravascular carcinomatosis of the brain: a report of two cases.

Although central nervous system (CNS) metastases are common in advanced cancer, CNS involvement solely by intravascular tumor cells, known as intravascular carcinomatosis, is extremely rare. We report two cases of brain metastasis in which tumor cells were restricted to the vascular lumina without parenchymal involvement, resulting in ischemic lesions. The first patient is a previously healthy young woman who presented with symptoms of community-acquired pneumonia and progressed to respiratory failure. Computed tomography of the brain showed infarcts of differing ages. At autopsy, she was found to have widely metastatic cervical squamous cell carcinoma and cerebral tumor emboli with multifocal infarcts, mainly microinfarcts. The second patient is an elderly man with cognitive impairment and mild Parkinsonism who presented with symptoms of a urinary tract infection. Magnetic resonance imaging of the brain showed atrophy and changes suggestive of chronic microvascular ischemic disease. Postmortem examination demonstrated prostatic adenocarcinoma and cerebral tumor emboli with multifocal infarcts. These cases illustrate that this pattern of intracranial metastasis may rarely be a cause of cerebral ischemic lesions and emphasize the importance of thorough pathologic examination of the brain.

High-grade neuroepithelial tumor with BCOR exon 15 internal tandem duplication-a comprehensive clinical, radiographic, pathologic, and genomic analysis.

High-grade neuroepithelial tumor with BCOR exon 15 internal tandem duplication (HGNET BCOR ex15 ITD) is a recently proposed tumor entity of the central nervous system (CNS) with a distinct methylation profile and characteristic genetic alteration. The complete spectrum of histologic features, accompanying genetic alterations, clinical outcomes, and optimal treatment for this new tumor entity are largely unknown. Here, we performed a comprehensive assessment of 10 new cases of HGNET BCOR ex15 ITD. The tumors mostly occurred in young children and were located in the cerebral or cerebellar hemispheres. On imaging all tumors were large, well-circumscribed, heterogeneous masses with variable enhancement and reduced diffusion. They were histologically characterized by predominantly solid growth, glioma-like fibrillarity, perivascular pseudorosettes, and palisading necrosis, but absence of microvascular proliferation. They demonstrated sparse to absent GFAP expression, no synaptophysin expression, variable OLIG2 and NeuN positivity, and diffuse strong BCOR nuclear positivity. While BCOR exon 15 internal tandem duplication was the solitary pathogenic alteration identified in six cases, four cases contained additional alterations including CDKN2A/B homozygous deletion, TERT amplification or promoter hotspot mutation, and damaging mutations in TP53, BCORL1, EP300, SMARCA2 and STAG2. While the limited clinical follow-up in prior reports had indicated a uniformly dismal prognosis for this tumor entity, this cohort includes multiple long-term survivors. Our study further supports inclusion of HGNET BCOR ex15 ITD as a distinct CNS tumor entity and expands the known clinicopathologic, radiographic, and genetic features.

Saksenaea infection masquerading as a brain tumor in an immunocompetent child.

Saksenaea species are a rare cause of mucormycosis, the majority associated with cutaneous and subcutaneous infections resulting from trauma in both immunocompromised and immunocompetent individuals. Unlike other causative agents of mucormycosis, cerebral infections are exceptionally rare. We describe the first case of isolated cerebral infection by Saksenaea in a 4-year-old previously healthy male child who presented with headaches. He had no past medical history other than an episode of febrile seizures. In addition to raising the awareness of an unusual presentation of infection by Saksenaea, this case highlights the importance of pathologic examination for the prompt diagnosis of mucormycosis as well as the specific fungal identification for treatment as Saksenaea spp. may be more susceptible to posaconazole and less susceptible to amphotericin B compared to more common causes of mucormycosis.

An Introduction to the Performance of Immunohistochemistry.

Immunohistochemistry (IHC) is a powerful technique that exploits the specific binding between an antibody and antigen to detect and localize specific antigens in cells and tissue, most commonly detected and examined with the light microscope. A standard tool in many fields in the research setting, IHC has become an essential ancillary technique in clinical diagnostics in anatomic pathology (Lin F, Chen Z. Arch Pathol Lab Med 138:1564-1577, 2014) with the advent of antigen retrieval methods allowing it to be performed conveniently on formalin fixed paraffin embedded (FFPE) tissue (Taylor CR, Shi S-R, Barr NJ. Techniques of immunohistochemistry: principles, pitfalls, and standardization. In: Dabbs DJ (ed) Diagnostic immunohistochemistry: theranostic and genomic applications, 3rd edn. Saunders, Philadelphia, 2010; Shi SR, Key ME, Kalra KL. J Histochem Cytochem 39:741-748, 1991) and automated methods for high volume processing with reproducibility (Prichard J, Hicks D, Hammond E. Automated immunohistochemistry overview. In: Fan L, Jeffrey P (eds) Handbook of practical immunohistochemistry: frequently asked questions, 2nd edn. Springer, New York, 2015). IHC is frequently utilized to assist in the classification of neoplasms, determination of a metastatic tumor's site of origin and detection of tiny foci of tumor cells inconspicuous on routine hematoxylin and eosin (H&E) staining. Furthermore, it is increasingly being used to provide predictive and prognostic information, such as in testing for HER2 amplification in breast cancer (Wolff AC, Hammond MEH, Hicks DG et al. Arch Pathol Lab Med 138:241-256, 2014) in addition to serving as surrogate markers for molecular alterations in neoplasms, including IDH1 and ATRX mutations in brain tumors (Appin CL, Brat DJ. Mol Aspects Med. 45:87-96, 2015). In this chapter we describe the basic methods of immunohistochemical staining which has become an essential tool in the daily practice of anatomic pathology worldwide.

Clinicopathologic features and pathogenesis of melanocytic colonization in atypical meningioma.

Only two prior cases of benign dendritic melanocytes colonizing a meningioma have been reported. We add a third case, describe clinicopathologic features shared by the three, and elucidate the risk factors for this very rare phenomenon. A 29 year-old Hispanic woman presented with headache and hydrocephalus. MRI showed a lobulated enhancing pineal region mass measuring 41 mm in greatest dimension. Subtotal resection of the mass demonstrated an atypical meningioma, WHO grade II, and the patient subsequently underwent radiotherapy. She presented 4 years later with diplopia, and MRI showed an enhancing extra-axial mass measuring 47 mm in greatest dimension and centered on the tentorial incisura. Subtotal resection showed a brain-invasive atypical meningioma with melanocytic colonization. The previous two cases in the literature were atypical meningiomas, one of which was also brain invasive. Atypical meningiomas may be at particular risk for melanocytic colonization as they upregulate molecules known to be chemoattractants for melanocytes. We detected c-Kit expression in a minority of the melanocytes as well as stem cell factor and basic fibroblast growth factor in the meningioma cells, suggesting that mechanisms implicated in normal melanocyte migration may be involved. In some cases, brain invasion with disruption of the leptomeningeal barrier may also facilitate migration from the subarachnoid space into the tumor. Whether there is low-level proliferation of the dendritic melanocytes is unclear. Given that all three patients were non-Caucasian, meningiomas in persons and/or brain regions with increased dendritic melanocytes may predispose to colonization. The age range spanned from 6 years old to 70 years old. All three patients were female. The role of gender and estrogen in the pathogenesis of this entity remains to be clarified. Whether melanocytic colonization may also occur in the more common Grade I meningiomas awaits identification of additional cases.

Early experience with formalin-fixed paraffin-embedded (FFPE) based commercial clinical genomic profiling of gliomas-robust and informative with caveats.

BACKGROUND: Commercial targeted genomic profiling with next generation sequencing using formalin-fixed paraffin embedded (FFPE) tissue has recently entered into clinical use for diagnosis and for the guiding of therapy. However, there is limited independent data regarding the accuracy or robustness of commercial genomic profiling in gliomas. METHODS: As part of patient care, FFPE samples of gliomas from 71 patients were submitted for targeted genomic profiling to one commonly used commercial vendor, Foundation Medicine. Genomic alterations were determined for the following grades or groups of gliomas; Grade I/II, Grade III, primary glioblastomas (GBMs), recurrent primary GBMs, and secondary GBMs. In addition, FFPE samples from the same patients were independently assessed with conventional methods such as immunohistochemistry (IHC), Quantitative real-time PCR (qRT-PCR), or Fluorescence in situ hybridization (FISH) for three genetic alterations: IDH1 mutations, EGFR amplification, and EGFRvIII expression. RESULTS: A total of 100 altered genes were detected by the aforementioned targeted genomic profiling assay. The number of different genomic alterations was significantly different between the five groups of gliomas and consistent with the literature. CDKN2A/B, TP53, and TERT were the most common genomic alterations seen in primary GBMs, whereas IDH1, TP53, and PIK3CA were the most common in secondary GBMs. Targeted genomic profiling demonstrated 92.3%-100% concordance with conventional methods. The targeted genomic profiling report provided an average of 5.5 drugs, and listed an average of 8.4 clinical trials for the 71 glioma patients studied but only a third of the trials were appropriate for glioma patients. CONCLUSIONS: In this limited comparison study, this commercial next generation sequencing based-targeted genomic profiling showed a high concordance rate with conventional methods for the 3 genetic alterations and identified mutations expected for the type of glioma. While it may not be feasible to exhaustively independently validate a commercial genomic profiling assay, examination of a few markers provides some reassurance of its robustness. While potential targeted drugs are recommended based on genetic alterations, to date most targeted therapies have failed in glioblasomas so the usefulness of such recommendations will increase with development of novel and efficacious drugs.