Computer-assisted stereotaxic biopsy for the diagnosis of primary central nervous system lymphoma.

Primary CNS lymphoma was diagnosed in 13 patients after stereotaxic biopsy of indeterminate intracerebral mass lesions. Two patients also had laser extirpation of CT-visible tumor. The group consisted of 10 men and 3 women, aged 17 to 81 (mean, 55 years; median, 60 years). The lesions on CT were characteristically hyperdense, homogeneously contrast-enhancing, and associated with mild to moderate mass effect. Five patients had more than one lesion visible on CT. Complete staging procedures for occult systemic lymphoma were negative in all 13 patients. The majority (eight) of the tumors were of the diffuse, large-cell type. Five biopsy specimens underwent special immunostaining as a supplemental diagnostic effort. Two patients with small lymphocytic tumors demonstrated features consistent with T cell phenotype. Two patients with diffuse, large-cell tumors were confirmed as B cell phenotype by monotypic immunoglobulin light chain content. Primary CNS lymphomas represent a treatable group of primary brain tumors. Because of their tendency to develop in deep cerebral regions, they are often inaccessible to conventional neurosurgical techniques. We propose that stereotaxic neurosurgery can provide safe and accurate diagnosis, which is a prelude to planning comprehensive management.