OS8.2 Risk stratification in chordoid meningioma depends on mutation status and epithelial differentiation

BACKGROUND

Meningiomas are heterogenous tumors and their pathologic classification in the WHO Classification of Tumors of the CNS comprises 13 recognized histologic variants. Chordoid meningioma is a rare and more aggressive histologic variant of meningioma. Due to paucity of cases, the molecular profiling and patient risk stratification were not addressed in this variant.

MATERIAL AND METHODS

We performed an integrated clinical, NHERF1 immunohistochemical (IHC) and next generation sequencing (NGS) analysis of WHO grade II chordoid meningiomas from 30 patients (35 cases), representing the largest study to date. The NGS was performed by using a custom Agilent-generated 295-gene library containing genes with recurrent mutations in adult and pediatric, primary and metastatic brain cancer. Five of these cases cases were confirmed by performing NGS at Tempus on the xT panel containing 596 genes, and an additional 10 atypical (non-chordoid) meningioma, WHO grade II, cases were sequenced at Tempus, for comparison.

RESULTS

The patients with chordoid meningioma have demographic characteristics different from the general population: younger age of onset (45 vs 65), skull base (SB) location for the female patients (6:1), and increased recurrence rate (25% at 5 years). NHERF1 microlumen extent directly correlated with skull base location (p=0.0002), and segregated tumors into three cell differentiation categories -fibroblastic (13.3%), epithelial/poorly-differentiated (26.7%) and epithelial/well-differentiated (60%). NGS identified NF2 and TRAF7, as the most common mutated genes, correlating with the location and epithelial differentiation of the tumors. Mutations in AKT1, KLF4 and MN1 were found in isolated well-differentiated skull base tumors. Mutations in genes not previously involved in meningioma pathogenesis were also found.

CONCLUSION

The integrated tumor analysis stratified the patients into: (1)

HIGH RECURRENCE RISK

, characterized by tumors harboring NF2 mutations and low epithelial differentiation and (2)

LOW RECURRENCE RISK

, characterized by tumors exhibiting either epithelial differentiation, skull base location and TRAF7/AKT1/KLF4 mutations, or fibroblastic differentiation, non-skull base location and other mutations. This is the first study of the integrated mutational landscape of chordoid meningioma with important implications for patient risk stratification and management.

Phenotypic variability of CADASIL and novel morphologic findings

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a non-arterio-atherosclerotic, non-amyloidotic arteriopathy affecting preferentially the small arteries and arterioles of the brain. The morphologic hallmark is the presence of a characteristic granular alteration of the arterial media that ultrastructurally corresponds to the accumulation of electron-dense material surrounding the smooth muscle cells. Although the presence of this granular osmiophilic material (GOM) was originally described as limited to brain vessels, identical electron microscopic findings have been demonstrated in the media of peripheral tissue arteries, allowing for a pathologic diagnosis of the disease by a simple skin, muscle or nerve biopsy. We report some atypical features identified in our CADASIL patients that broaden the phenotypic expression of this disease. Firstly, we identified a cortical infarct in an otherwise typical CADASIL patient. Secondly, we observed GOM in skin arteries of a 30-year-old man with hemiplegic migraine, the son of a woman who had died with CADASIL. This confirms that it may be possible to diagnose the disease at a preclinical stage by the ultrastructural evaluation of peripheral tissue biopsy material, particularly for individuals for whom there is a supporting family history. Thirdly, ultrastructural examination of the skin, and subcutaneous and striated muscle of an unrelated and apparently sporadic patient with neuropathologic and neuroradiologic evidence of CADASIL in meningeal and cerebral vessels failed to reveal diagnostic lesions in peripheral arteries. Thus, the possibility of a false-negative pathologic diagnosis in patients with a clinicoradiologic diagnosis of CADASIL, if one relies solely on a peripheral tissue biopsy, does exist. Additionally, we have identified heat shock proteins (Hsp70 and alphaB crystallin) and ubiquitin in the vascular myocytes of affected arteries. <alpha>B crystallin also seemed to be deposited extracellularly, which suggests that GOM also might be immunoreactive for alphaB crystallin.

[Postoperative epidural analgesia with Bupivacaine-HCl 0.06%/Fentanyl 0.0002%. Experiences and physicochemical stability in infusion bags]

Continuous epidural infusion of bupivacaine with the opioid fentanyl represents an effective analgesic method in the therapy of strong postoperative pain after major surgery. Preparation of the required infusion solution in syringes with a volume of 50 ml immediately prior to administration is routinely performed by nursing staff in Germany. The effort required for the preparation is associated with logistical and pharmaceutical difficulties. The preparation of a mixture of bupivacaine hydrochloride 0.06% and fentanyl 0.0002% in 250 ml infusion bags at the pharmacy of the University Hospital Mainz is described. To determine the physicochemical stability, the concentration of bupivacaine-HCl and fentanyl was assessed using HPLC over a period of 32 days; in addition the pH values were determined. After 32 days 95% of the bupivacaine hydrochloride and fentanyl baseline values were recorded. The pH baseline value had decreased from 5.48-5.52 to 0.5-0.7 units. The measured values confirm the physicochemical stability of the mixture of bupivacaine hydrochloride 0.06% and fentanyl 0.0002% over a period of 32 days. The infusion bag can be stored for 4 weeks at room temperature.

The properties of deposited metal clusters generated by laser evaporation

Metal clusters have been produced using a laser evaporation source. A Nd-YAG laser beam focused onto a solid silver rod was used to evaporate the material, which was then cooled to form clusters with the help of a pulsed high pressure He beam. TOF mass spectra of these clusters reveal a strong occurrence of small and medium sized clusters (n less than 100). Clusters were also deposited onto grid supported thin layers of carbon-films which were investigated by transmission electron microscopy. Very high resolution pictures of these grids were used to analyze the size distribution and the structure of the deposited clusters. The diffraction pattern caused by crystalline structure of the clusters reveal 3- and 5-fold symmetries besides the pattern reflecting the fcc bulk structure. This can be explained in terms of icosahedron and cuboctahedron type clusters deposited on the surface of the carbon layer. There is strong evidence that part of these cluster geometries had already been formed before the deposition process. The non-linear dependence of the cluster size and the cluster density on the generating conditions is discussed.