RELIABILITY OF HISTOLOGICAL DIAGNOSIS INCLUDING GRADING IN GLIOMAS BIOPSIED BY IMAGE-GUIDED STEREOTAXIC TECHNIQUE

We report clinical and pathological data of 419 image-guided stereotac tic biopsies. In the present series the diagnostic yield, estimated by comparing the original histological diagnoses with follow-up data, wa s found to be approximately 94 % in gliomas. As it has been suggested that malignancy of astrocytic gliomas may be considerably underestimat ed in the small tissue samples obtained by stereotactic biopsy, we hav e reviewed 160 adult, diffuse supratentorial astrocytic tumours, corre lating the original Kernohan tumour grades with survival. In this grad ing system, although there was generally a good correlation between hi stological grade and survival probability (P < 0.0001), no distinction could be made between the grade 3 (anaplastic astrocytoma) and grade 4 (glioblastoma) groups. Tumour grades obtained by applying the criter ia of the more recent Daumas-Duport grading system were also determine d and correlated with survival. These latter tumour grades not only co rrelated well with survival (P < 0.0001), but also enabled us to ident ify a group of patients with intermediate grade malignancy (grade 3, a naplastic astrocytoma), surviving longer than those with grade 4 tumou rs. Image-guided stereotactic biopsy is a useful means of providing ti ssue samples for histological diagnosis of brain neoplasms, including gliomas. Histological grading of adult, diffuse supratentorial astrocy tic gliomas diagnosed by this technique is possible and should be carr ied out using an appropriate grading system.