Importance of image-guided stereotactic biopsy to confirm diagnosis in an oncological setting

In current practice, the neurosurgical community relies heavily on computed tomography (CT) and magnetic resonance imaging (MRI) for making the diagnosis of brain lesions, especially when surgically inaccessible. However, the specificity of these neuroimaging modalities remains limited, and errors in diagnosis are frequent. In an attempt to ascertain how often the diagnosis based on imaging studies is proved wrong by biopsy, we reviewed the findings from 100 consecutive stereotactic biopsies performed in an oncological setting. The records of 100 consecutive stereotactic biopsies were postoperatively reviewed. The preoperative clinical and radiologic differential diagnoses were compared with diagnosis made on tissue retrieved by biopsy. In 19% of patients, the preoperative clinical and radiological diagnoses and postoperative diagnosis were different, and reliance on brain imaging data alone would have led to an incorrect tentative diagnosis and the wrong choice of treatment. The high rate of discrepancy between clinical and radiological diagnoses on the one hand and biopsy-proven diagnosis on the other hand is a compelling reason to establish tissue diagnosis. Stereotactic biopsies of brain lesions are relatively safe and should be performed in cases where tissue characteristics affect prognosis, where therapy carries an inherent risk, and in those patients under treatment for cancer or immune deficiencies in whom there is an unusually broad differential diagnosis.