Nicolas Macagno

Differential Diagnosis of Meningeal SFT-HPC and Meningioma: Which Immunohistochemical Markers Should Be Used?

Meningeal solitary fibrous tumors–hemangiopericytomas (SFT-HPC) and meningiomas can be difficult to distinguish on histologic examination. STAT6 immunohistochemistry (IHC) is a reliable diagnostic marker of SFT-HPCs. Recently, GRIA2 has also been reported to be a diagnostic marker of SFT-HPC, although no extensive data are available for meningeal SFT-HPCs yet. The aim of this study was to test their diagnostic performance in a large cohort of SFT-HPCs and meningiomas. IHC analyses for GRIA2 and STAT6 were performed on tissue microarrays containing 76 SFT-HPCs and 181 meningiomas. Results were compared with previous data with ALDH1 and CD34. Two different anti-STAT6 antibodies were tested: SC-20 polyclonal and YE361 monoclonal antibody. Ninety-six percent of meningeal SFT-HPCs but no meningioma displayed nuclear STAT6 positivity. With SC-20 antibody, concomitant cytoplasmic staining for STAT6 was observed in >50% of all cases, including meningiomas. However, using YE361 antibody, cytoplasmic staining was absent, and nuclear signal intensity was stronger leading to better interpretation of STAT6 IHC. GRIA2 was positive in 84% of SFT-HPCs and in 16% of meningiomas. STAT6 had excellent sensitivity (96%) and specificity (100%), ALDH1 and GRIA2 had same sensitivity (84%), but ALDH1 and CD34 had better specificity than GRIA2 (97% and 96% vs. 84%, respectively). For the differential diagnosis of SFT-HPCs versus meningiomas, the best diagnostic approach is to perform STAT6, followed by ALDH1 and CD34 in the case of uncommon STAT6-negative cases. Because of meningioma positivity, GRIA2 seems less useful in this indication.

Prognostic value of the Hippo pathway transcriptional coactivators YAP/TAZ and β1-integrin in conventional osteosarcoma

Introduction Currently, very few studies are available concerning the mammalian Hippo pathway in bone sarcomas. YAP/TAZ transcription co-activators are key downstream effectors of this pathway and may also have oncogenic properties. Additionally, recent in-vitro experiments showed that expression of β1-integrin promoted metastasis in osteosarcomas. This study investigated the expression of YAP/TAZ and β1-integrin in human osteosarcomas. Materials and methods We performed automated immunohistochemistry on tissue-microarrays (TMA) in which 69 conventional osteosarcomas biopsies performed prior to chemotherapy were embedded. Cellular localization and semi-quantitative analysis of each immunostain was performed using Immunoreactive Score (IRS) and correlated to clinico-pathological data. Results Cytoplasmic expression of β1-integrin was noted in 54/59 osteosarcomas (92%), with 33/59 cases (56%) displaying membranous staining. YAP/TAZ was expressed in 27/45 osteosarcomas (60%), with 14 cases (31%) showing cytoplasmic expression while 13 other cases (28%) displayed nuclear expression. No link was found between YAP/TAZ or β1-integrin expression and response to chemotherapy. In univariate analysis, YAP/TAZ immunoreactive score was pejoratively correlated with overall survival (p = 0.01). Expression of β1-integrin on cell membrane was also pejorative for OS (p = 0.045). In multivariate analysis, YAP/TAZ nuclear expression was an independent prognostic factor for PFS (p = 0.035). Conclusion this study indicates that β1-integrin and YAP/TAZ proteins are linked to prognosis and therefore could be therapeutic targets in conventional osteosarcomas.

Hgnet-bcor Tumors of the Cerebellum: Clinicopathologic and Molecular Characterization of 3 Cases

The central nervous system (CNS) high-grade neuroepithelial tumor with BCOR alteration (CNS HGNET-BCOR) is a recently described molecular entity. We report 3 new CNS HGNET-BCOR cases sharing common clinical presentation and pathologic features. The 3 cases concerned children aged 3 to 7 years who presented with a voluminous mass of the cerebellum. Pathologic features included proliferation of uniform spindle to ovoid cells with fine chromatin associated with a rich arborizing capillary network. Methylation profiling classified these cases as CNS HGNET-BCOR tumors. Polymerase chain reaction analysis confirmed the presence of internal tandem duplications in the C-terminus of BCOR (BCOR-ITD), a characteristic of these tumors, in all 3 cases. Immunohistochemistry showed a strong nuclear BCOR expression. In 2 cases, local recurrence occurred within 6 months. The third case, a patient who received a craniospinal irradiation after total surgical removal followed by a metronomics maintenance with irinotecan, temozolomide, and itraconazole, is still free of disease 14 months after diagnosis. In summary, CNS HGNET-BCOR represents a rare tumor occurring in young patients with dismal prognosis. BCOR nuclear immunoreactivity is highly suggestive of a BCOR-ITD. Whether CNS HGNET-BCOR should be classified among the category of “embryonal tumors” or within the category of “mesenchymal, nonmeningothelial tumors” remains to be clarified. Because CNS HGNET-BCOR share pathologic features and characteristic BCOR-ITD with clear cell sarcoma of the kidney, these tumors may represent local variants of the same entity.

Giant congenital melanocytic nevus with vascular malformation and epidermal cysts associated with a somatic activating mutation in BRAF

Giant congenital melanocytic nevi may be symptomatically isolated or syndromic. Associations with capillary malformations are exceptional, and development of epidermal cysts has not been described. A 71‐year‐old patient with a giant congenital melanocytic nevus (CMN) of the lower back, buttocks, and thighs was asymptomatic except for unexpected hemorrhage during partial surgical excision years before. Blunt trauma at age 64 initiated recurrent, severe pain under the nevus; multiple large epidermal cysts then developed within it. Imaging and biopsy showed a large, non‐pulsatile venous malformation intermingled with the deep nevus. A low‐abundance, heterozygous BRAF c.1799T>A (p.V600E) mutation was present in both gluteal and occipital congenital nevi; additional mutations in NRAS, GNAQ, GNA11, HRAS, or PIK3CA were undetectable. This is the first demonstration of a recurrent BRAF mutation in multiple large congenital nevi from the same individual, confirming that this malformation can have multiple genetic origins. Early constitutive activation of BRAF can therefore cause unusual associations of giant nevi with vascular malformations, indicating that both pigment and endothelial cell physiology may be affected by mosaic RASopathies.

Proof of concept: prognostic value of the plasmatic concentration of circulating cell free DNA in desmoid tumors using ddPCR

Since desmoid tumors (DT) exhibit an unpredictable clinical course, with stabilization and/or spontaneous regression, an initial “wait-and-see” policy is the new standard of care–thus, the actual challenge is to identify early factors of progression. We present a method of detection of CTNNB1 mutations using a targeted digital droplet PCR (ddPCR) on cell-free DNA (cfDNA) extracted from blood samples of 31 DT patients. Furthermore, we analyzed the correlation between DT evolution and plasmatic concentration of total and mutated cfDNA at the time of diagnosis. Circulating copies of CTNNB1 mutants (ctDNA) were detected in the plasma of 6 patients (33%) but their concentration was not correlated with evolution of the tumor. Concentration of total cfDNA was higher in the plasma of patients with progressive desmoids (p = 0,0009). Using a threshold <900 copies/mL of plasma to detect indolent desmoid and a threshold >1375, it was possible to predict desmoid evolution for 65% of patients by measuring the quantity of circulating DNA in their plasma as early as the time of diagnosis. Albeit showing that the detection of CTNNB1 mutants is possible in the plasma of patients harboring a desmoid tumor, the results of this preliminary study raise the hypothesis that most of the circulating DNA detected in their plasma is derived from non-neoplastic cells, most likely normal neighboring tissues being actively invaded. Our results open the perspective of using cfDNA as a biomarker to predict prognosis at the time of diagnosis and assess tumor dynamics to optimize the treatment strategy.

IDH2 mutations are commonly associated with 1p/19q codeletion in diffuse adult gliomas

716 IDH2 mutations are commonly associated with 1p/19q codeletion in diffuse adult gliomas Diffuse gliomas are classified according to the 2016 World Health Organization (WHO) Classification of Tumors of the Central Nervous System, 1 which combines histological and molecular features. Diagnosis requires the assessment of mutations in the isocitrate dehydrogenase genes (IDH1 and IDH2), key genetic alterations characterizing gliomas with favorable outcome. 2 Because IDH1 and IDH2 are highly similar enzymes, the WHO classification, as most of the current studies, combines these mutations into the same molecular group; however, it is unclear whether these tumors share the same characteristics. We analyzed data from 1517 patients included in the French POLA Network to investigate differences between IDH1-and IDH2-mutant gliomas. Inclusion criteria were the written consent of the patient for clinical data collection and genetic analysis and sufficient material for molecular studies allowing classification according to the 2016 WHO classification. IDH1-R132H mutational status was evaluated using automated immunohistochemistry in all cases (n = 1517). Direct sequencing 3 was performed in 978 cases and demonstrated IDH mutation in 573 cases (this includes confirmation of IDH1-R132H mutation in 468 cases, other IDH1 mutations in 61 cases, and IDH2 mutation in 44 cases). The 1p/19q codeletion status was determined based on single nucleotide polymor-phism arrays, comparative genomic hybridization arrays, and/ or microsatellite marker analysis. 3 The following data were recorded: age, sex, follow-up, and MRI features (tumor location , extension, contrast enhancement, edema). All statistical analysis was done using IBM SPSS statistics software version 23. Chi-square test was used to compare qualitative variables. Continuous variables were compared using the Mann– Whitney U-test, and the Kaplan–Meier method was used to estimate survival distributions. Among the 1517 patients, 1025 had an IDH-mutant tumor: 96% were IDH1-mutant and 4% IDH2-mutant. Integrated diagnoses are summarized in Fig. 1. The frequency of 1p/19q code-letion was higher in the IDH2-mutant group compared with the IDH1-mutant group (91% vs 48%, P < 0.001). Wang and coworkers previously reported higher frequency of 1p/19q codeletion in IDH2-mutant gliomas (9/18 samples) compared with IDH1-mutant. 4 The percentage of each category in our study does not reflect the normal distribution of glioma because of the inclusion criteria in the POLA Network (ie, high-grade glioma with oligodendroglial component). However, the higher proportion of 1p/19q codeleted glioma in the IDH2-mutant group cannot be attributed to the inclusion criteria. Because the main population of glioma associated with IDH2 mutation was 1p/19q codeleted anaplastic oligodendroglioma, we focused on this subgroup to search for differences compared with IDH1 mutation. Among these patients (n = 474), we did not observe any difference in terms of age, sex, progression free survival, or overall survival between IDH1-and IDH2-mutant tumors. However, IDH2-mutant anaplastic oli-godendrogliomas presented more frequently with multilobar extension (56% of the IDH2-mutant vs 35% of the IDH1-mutant, P = 0.015) and edema (79% vs 57%, P = 0.02). Furthermore, bifrontal location with corpus callosum involvement was more frequent in IDH2-mutant compared with IDH1-mutant tumors (41% vs 16%, P < 0.001). IDH mutation is supposed to be one of the first hits of gliomagenesis, 5 resulting in production of an oncome-tabolite, D-2-hydroxyglutarate (D-2HG), which impacts the α-ketoglutarate–dependent dioxygenase functions. Previous studies demonstrated that the potential for IDH-mutant enzymes to produce D-2HG depends on the mutation type. 6 Based on our observations, we could hypothesize that the higher D-2HG accumulation induced by IDH2 mutation may lead to a phenotype that is favorable to 1p/19q chromosomal loss. It may also impact distinct cellular pathways that promote a more invasive phenotype. Whether IDH1 or IDH2 mutations impact distinct glial precursor cells with differential invasive properties remains to be elucidated. In conclusion, our results illustrate that IDH2-mutant glio-mas are commonly associated with 1p/19q codeletion. Most of IDH2-mutant anaplastic oligodendroglioma 1p/19q codeleted are multilobar. Understanding the genomic events involved in these specificities may represent a step forward for therapeutic development.

Duplications of KIAA1549 and BRAF screening by Droplet Digital PCR from formalin-fixed paraffin-embedded DNA is an accurate alternative for KIAA1549 - BRAF fusion detection in pilocytic astrocytomas

Pilocytic astrocytomas represent the most common glioma subtype in young patients and account for 5.4% of all gliomas. They are characterized by alterations in the RAS–MAP kinase pathway, the most frequent being a tandem duplication on chromosome 7q34 involving the BRAF gene, resulting in oncogenic BRAF fusion proteins. BRAF fusion involving the KIAA1549 gene is a hallmark of pilocytic astrocytoma, but it has also been recorded in rare cases of gangliogliomas, 1p/19q co-deleted oligodendroglial tumors, and it is also a common feature of disseminated oligodendroglial-like leptomeningeal neoplasm. In some difficult cases, evidence for KIAA1549-BRAF fusion is of utmost importance for the diagnosis. Moreover, because the KIAA1549-BRAF fusion constitutively activates the MAP kinase pathway, it represents a target for drugs such as MEK inhibitors, and therefore, the detection of this genetic abnormality is highly relevant in the context of clinical trials applying such new approaches. In the present study, we aimed to use the high sensitivity of Droplet Digital PCR (DDPCR™) to predict KIAA1549-BRAF fusion on very small amounts of formalin-fixed paraffin-embedded tissue in routine practice. Therefore, we analyzed a training cohort of 55 pilocytic astrocytomas in which the KIAA1549-BRAF fusion status was known by RNA sequencing used as our gold standard technique. Then, we analyzed a prospective cohort of 40 pilocytic astrocytomas, 27 neuroepithelial tumors remaining difficult to classify (pilocytic astrocytoma versus ganglioglioma or diffuse glioma), 15 dysembryoplastic neuroepithelial tumors, and 18 gangliogliomas. We could demonstrate the usefulness and high accuracy (100% sensitivity and specificity when compared to RNA sequencing) of DDPCR™ to assess the KIAA1549-BRAF fusion from very low amounts of DNA isolated from formalin-fixed paraffin-embedded specimens. BRAF duplication is both necessary and sufficient to predict this fusion in most cases and we propose that this single analysis could be used in routine practice to save time, money, and precious tissue.

Negative Survival Impact of High Radiation Doses to Neural Stem Cells Niches in an IDH-Wild-Type Glioblastoma Population

Aims: Assess the impact of radiation doses to neural stem cell (NSC) niches in patients with IDH-wild-type glioblastoma. Materials and Methods: Fifty patients were included in the study. NSC niches [SubVentricular Zone (SVZ) and Sub Granular Zone (SGZ)] were contoured by fusing CT scans and pre-therapy MRI, Tumor location defined ipsilateral and contralateral SVZ and SGZ. Prognostic significance of clinical, biological and dosimetric parameters were examined. We generated a Recursive Partitioning Analysis (RPA) model with independent prognostic classes. Results: Median follow-up: 23.8 months. Event free and overall survival (OS): 10 and 19.1 months. Incomplete surgery, PTV (planning target volume), ipsilateral SVZ or NSC niche mean dose > 57.4 Gy, contralateral NSC niche mean dose > 35 Gy and bilateral NSC niche mean dose > 44 Gy were significantly correlated with reduced OS. Only EGFR amplification was an independent prognostic factor (p = 0.019) for OS. RPA generated independent risk groups: 1 (low risk): [ipsilateral NSC mean dose (INMD) < 58.01 Gy and methylated MGMT promoter], 2: (INMD < 58.01 Gy and unmethylated MGMT promoter and contralateral SVZ mean dose < 18.6 Gy; p = 0.43), 3: (INMD < 58.01 Gy and unmethylated MGMT promoter and contralateral SVZ mean dose > 18.6 Gy; p = 0.002) and 4: (very high risk) (INMD > 58.01 Gy; p < 0.001). Conclusion: High radiation doses to ipsilateral NSC and contralateral SVZ could have a negative impact on overall survival in IDH-wild-type glioblastoma population.

Grading of meningeal solitary fibrous tumors/hemangiopericytomas: analysis of the prognostic value of the Marseille Grading System in a cohort of 132 patients: Grading of meningeal solitary fibrous tumors

The finding that meningeal solitary fibrous tumors (SFTs) and meningeal hemangiopericytomas (HPCs) are both characterized by NAB2‐STAT6 gene fusion has pushed their inclusion in the WHO 2016 Classification of tumors of the central nervous system (CNS) as different manifestations of the same entity. Given that the clinical behavior of the CNS SFT/HPC spectrum ranges from benign to malignant, it is presently unclear whether the grading criteria are still adequate. Here, we present the results of a study that analyzed the prognostic value of an updated version of the Marseille Grading System (MGS) in a retrospectively assembled cohort of 132 primary meningeal SFTs/HPCs with nuclear overexpression of STAT6. The median patient follow‐up was 64 months (range 4–274 months); 73 cases (55%) were MGS I, 50 cases (38%) MGS II and 9 cases (7%) were MGS III. Progression‐free survival (PFS) and disease‐specific survival (DSS) were investigated using univariate analysis: the prognostic factors for PFS included MGS, extent of surgery, radiotherapy, chemotherapy and mitotic activity ≥5/10 high‐power field (HPF). Moreover, MGS, radiotherapy, mitotic activity ≥5/10 HPF, and necrosis were the prognostic factors measured for DSS. In multivariate analysis, extent of surgery, mitotic activity ≥5/10 HPF, MGS I and MGS III were the independent prognostic factors measured for PFS while necrosis, MGS III and radiotherapy were the independent prognostic factors for DSS. In conclusion, our results show that assessing the malignancy risk of SFT/HPC should not rely on one single criterion like mitotic activity. Therefore, MGS is useful as it combines the value of different criteria. In particular, the combination of a high mitotic activity and necrosis (MGS III) indicates a particularly poor prognosis.

Hereditary lysozyme amyloidosis with sicca syndrome, digestive, arterial, and tracheobronchial involvement: case-based review

Lysozyme amyloidosis (ALys) is a rare autosomal dominant hereditary systemic amyloidosis associated with a large spectrum of clinical manifestations. ALys phenotype mainly involves the digestive tract, liver and spleen, kidneys, lymph nodes, skin, and lachrymal and salivary glands. Very recently, cardiac involvement and peripheral neuropathy associated with a new p.Leu102Ser variant of lysozyme have been documented. In the present observation, we extend the phenotypic heterogeneity of ALys to the tracheobronchial tree with histologically proven bronchial ALys-amyloid deposits. We report the case of a 62-year-old man of Italian origin (Piedmont) diagnosed with ALys associated with the p.Trp82Arg variant. The patient complained of upper digestive symptoms, sicca syndrome, and lately recurrent pulmonary infections. Thoracic endoscopy revealed a fragile, inflammatory, and granulomatous aspect of the bronchi. Amyloid deposits were observed in the upper digestive tract, salivary glands, temporal artery, and tracheobronchial tree. Symptomatic treatment was offered. Recurrent pulmonary infections occurred during the follow-up. Lung involvement in hereditary ALys has only been exceptionally described. Although vascular involvement has already been reported in ALys in many organs, it never concerned cranial arteries. This case highlights the systemic nature of the amyloid protein variant deposits and expands the spectrum of clinical manifestations to chest involvement. The literature review highlights that hereditary ALys with the p.Trp82Arg variant is frequent in patients coming from Piedmont (Italy). Due to diffuse organs involvement related to ALys, it is important not to misdiagnose ALys for AL amyloidosis, the most frequent form of amyloidosis.