Concordance and diagnostic yield of stereotactic biopsies for posterior fossa: Technique and experience in a reference hospital

Aim: Describe our stereotactic brain biopsy (SBB) technique for intra-axial lesions of the posterior fossa, evaluate its effective-ness and safety, and compare them with other series. Material and methods: Retrospective study in ten consecutive patients, whose variables were age, gender, location of the lesions, clinical, radiological, and histopathological diagnoses, complications, and mortality, for analysis using descriptive statistics and tests of concordance and diagnostic validity. Results: Lesions were pontine in seven cases, and pontomedullary in three occasions, with histopathological diagnoses of four Grade II astrocytomas, two Grade IV astrocytomas, two infectious process, one neuroblastic tumor, and one cavernous malformation, whose frequency differs from the previous reports (chi(2) = 0.07). The clinical-radiological concordance was poor (kappa = 0.20). The validity of the clinical diagnosis had intermediate values (Sn = 66.7%, Sp = 75%), while radiological studies were more sensitive (Sn = 100%, Sp = 25%). A definitive diagnosis was obtained in all procedures, with no permanent morbidity or mortality because of the surgery. Conclusion: The SBB technique for posterior fossa implemented in our hospital shows high diagnostic yield, as well as absolute safety for the patient.