Fine-needle aspiration biopsy of the central nervous system performed freehand under computed tomography guidance without stereotactic instrumentation.

Abstract

Biopsy of the central nervous system (CNS) has been reported previously using relatively large-caliber (12-17-gauge) biopsy instruments with or without stereotactic guidance. In this series, fine-needle aspiration biopsies (FNABs) were performed using a smaller diameter needle to evaluate mass lesions of the CNS. One hundred thirty FNABs were performed freehand under computed tomography (CT) guidance without stereotactic instrumentation guidance using a 22-gauge needle. A definitive diagnosis was rendered in 97 of 130 FNABs (75%), including glioblastoma multiforme (GBM) (n = 33 biopsies); anaplastic astrocytoma (n = 14 biopsies); metastatic carcinoma (n = 13 biopsies); low-grade astrocytoma (LGA) (n = 10 biopsies); lymphoma (n = 7 biopsies); oligodendroglioma (n = 5 biopsies); reactive gliosis (n = 2 biopsies); and abscess (n = 13 biopsies), with the infectious agent identified in 7 of 13 biopsies. Immunohistochemistry was employed in 51 biopsies to assist in determining either the cell type or the infectious agent. Indefinite diagnoses were rendered in 33 patients (25%), including LGA versus gliosis (n = 8 patients), necrosis and/or inflammation (n = 3 patients), nondiagnostic material (n = 17 patients), suspicious for lymphoma (n = 2 patients), suspicious for GBM (n = 2 patients), and high-grade neoplasm not otherwise classified (n = 1 patient). There was no morbidity or mortality attributed to the procedure. FNAB of CNS mass lesions established a diagnosis based on cytologic interpretation in 75% of biopsies without morbidity or mortality. Because morbidity and mortality rates in CT-guided biopsies utilizing stereotactic techniques with large-caliber needles have been reported as high as 14% and 4.7%, respectively, freehand FNAB under CT guidance may be a preferred initial method for evaluating mass lesions of the CNS.