Computed tomography in the diagnosis of malignant brain tumours: do all patients require biopsy?

Abstract

SUMMARY A proportion of patients with computed tomographic (CT) scan appearances of malignant brain tumour undergo conservative management, despite the absence of histological confirmation of the diagnosis. Concern that this policy risked misdiagnosing a benign tumour prompted us to examine the accuracy of CT scanning in diagnosing malignant lesions. The study was designed to determine whether within a group of 300 patients with intracerebral mass lesions of known pathology, two sub-groups existed: one with appearances so specific for malignant glioma that biopsy was unnecessary, and the other in which the appearances were characteristic of malignancy, though not specific for glioma. Three neuroradiologists independently reviewed the CT scans, together with brief clinical details. When diagnosing malignant tumours, all made errors: nine benign lesions were considered to be malignant. When diagnosing malignant glioma, one neuroradiologist made errors, but the other two adopted a more cautious approach and were accurate. The restricted a "certain" diagnosis to about one in five scans considered to show malignant tumour. Those diagnosed specifically as malignant glioma were intrinsic, irregular, mixed density lesions, exhibiting variable enhancement and infiltrating the peri-ventricular tissues, especially the corpus callosum. Using these criteria, they could correctly identify a small proportion ofpatients with malignant gliomas. In all other patients, biopsy remains the only means of obtaining a definitive diagnosis.

Intracranial neoplasmin Ibadan, Nigeria

“…Although the diagnostic yield of intracranial neoplasms has improved with the acquisition of a computerised tomography scanner in the University College Hospital, Ibadan, it is apparent that there will always be a need for histopathologists to confirm the diagnosis of intracranial neoplasms and to provide the definitive diagnosis in a significant number of cases where the CT scanner is found not to be helpful (23).…”

Medulloblastoma of the Cerebellopontine Angle-Case Report-

“…Preoperative evaluation of the metabolite pattern of intracranial lesions allows up to a 95% accurate histological diagnosis of pediatric posterior fossa tumors. 3) Clinical use of the technique 3,9,33,35) suggests that proton MR spectroscopy might be the most beneficial preoperative noninvasive diagnostic tool to differentiate the rare intraaxial brain tumors of the CPA, although no examples have so far been reported of CPA medulloblastoma. 22,34) …”

“…The available clinical and neuroimaging findings of our patient were insufficient for establishing the correct preoperative diagnosis of a CPA medulloblastoma. Accurate prediction of tumor histology is still limited based on MR imaging and CT. 9,35) Proton MR spectroscopy is a noninvasive technique for the spatial characterization of biochemical markers in tissues. Preoperative evaluation of the metabolite pattern of intracranial lesions allows up to a 95% accurate histological diagnosis of pediatric posterior fossa tumors.…”

Management of malignant glioma: role of surgery in relation to multimodality therapy

“…CT scanning is generally accurate in identifying malignant glioma and resolution is even greater with MRI (Choksey et al, 1989;Rajan et al, 1994). Although these imaging modalities result in only occasional misdiagnosis, the importance of precise histological diagnosis in planning treatment and in estimating prognosis is of such great value that biopsy, when feasible, is desirable.…”