Two cases of asymptomatic Teflon granulomas following microvascular decompression mimicking cerebellopontine angle tumours: lessons learnt in the neuro-oncology multidisciplinary team

We present the cases of two patients with asymptomatic Teflon granulomas which were incidentally found years after microvascular decompression and presented to the neuro-oncology multidisciplinary team as possible cerebellopontine angle tumours. Teflon granulomas can be asymptomatic and they can radiologically resemble cerebellopontine angle tumours. It is important that all relevant information is available to the neuro-oncology multidisciplinary team for adequate assessment and appropriate treatment recommendations.

Evaluation of Extra Axial Cerebellopontine Angle Tumours through MRI

Aim: This study aimed to evaluate the incidence of extra-axial cerebellopontine angle tumours and to characterize extra-axial cerebellopontine angle tumours. Methods: The study was carried out in Dhaka Medical College for the duration of 2 years from July 2016 to July 2018. All patients with clinical suspicion of CP angle tumours subjected 1.5 T MR imaging system. Total 30 patients were evaluated during this period. Results: Extra-axial CPA tumours accounts for 7-10% of brain tumours. Most common extraaxial CPA tumour is schwannoma (60%), followed by meningioma (27%), epidermoid (7%), arachnoid cysts (7%). 51-60 years is the most common age group involved. Schwannomas are common extra-axial CPA tumours which are enhancing round masses most commonly arise from the vestibular nerve and associated with enlargement of the internal auditory canal. Meningiomas are the second most common extra-axial CP angle tumours which oval or hemispheric lesions with a broad attachment to tentorium or petrous dura matter. Conclusion: MRI is the most sensitive noninvasive modality to characterize extra-axial CPA tumours. MRI identifies the location and extension of the lesions based on their characteristic signal and enhancement pattern on contrast. J Dhaka Medical College, Vol. 27, No.2, October, 2018, Page 104-107

Inter-observer variability between radiologists reporting on cerebellopontine angle tumours on magnetic resonance imaging

Background:Studies demonstrate the significance of intra- and inter-observer variability when measuring cerebellopontine angle tumours on magnetic resonance imaging, with measured differences as high as 2 mm.Objective:To determine intra- and inter-observer measurement variability of cerebellopontine angle tumours in a specialised institution.Methods:The magnetic resonance imaging maximal diameter of 12 randomly selected cerebellopontine angle tumours were independently measured by 4 neuroradiologists at a tertiary referral centre using a standard definition for maximal tumour diameter. Average deviation and intraclass correlation were subsequently calculated.Results:Inter-observer difference averaged 0.33 ± 0.04 mm (range, 0.0–0.8 mm). Intra-observer measurements were more consistent than inter-observer measurements, with differences averaging 0.17 mm (95 per cent confidence interval = 0.27–0.06, p = 0.002). Inter-observer reliability was 0.99 (95 per cent confidence interval = 0.97–0.99), suggesting high reliability between the readings.Conclusion:The use of a standard definition for maximal tumour volume provided high reliability amongst radiologists' readings. To avoid oversizing tumours, it is recommended that conservative monitoring be conducted by the same institution with thin slice magnetic resonance imaging scans.