Intraoperative rapid diagnosis of primary central nervous system lymphomas: advantages and pitfalls

To study the advantages and pitfalls of intraoperative rapid diagnosis (IRD) of primary central nervous system lymphomas (PCNSL), pathology reports and frozen sections in our institution were reviewed. We examined 27 cases of PCNSL, one case of anaplastic glioma, and one case of metastatic brain tumor that were diagnosed on neuroimaging. Fifteen cases of intraoperative cytological preparations were also reviewed in a correlative manner. Among the 27 cases initially diagnosed as PCNSL, 18 were also diagnosed as PCNSL by IRD. However, IRD identified four of the 27 cases as gliosis, two as demyelination, one as atypical epithelial cells, one as malignant glioma and anaplastic astrocytoma. In addition, the case identified as metastatic brain tumor on neuroimaging was corrected to a diagnosis of PCNSL based on IRD. The final accuracy of IRD in the present study was 89.6% (26/29). After postoperative definitive diagnosis, two cases of anaplastic astrocytoma and one case of PCNSL by IRD were corrected to PCNSL, anaplastic oligodendroglioma and demyelination, respectively. PCNSL were sometimes histologically indistinguishable from malignant gliomas or demyelinating diseases in the present study, particularly in frozen sections. Notably, all cases for which both intraoperative cytology and frozen section were performed concomitantly were correctly diagnosed in the present study. In particular, lymphoglandular bodies were highly characteristic cytological findings of PCNSL. Both intraoperative cytology and frozen sections should therefore be performed concomitantly when PCNSL are suspected.