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

Abstract

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.

Primary central nervous system lymphomas and related diseases: Pathological characteristics and discussion of the differential diagnosis

“…In such cases, histopathological findings showed nonspecific lymphocytic inflammatory changes in the first biopsy. We also reported a case of spontaneous regression of a primary CNS lymphoma that was like demyelinating disease and was not treated with steroid administration . Initial MRI showed a right occipital lesion, but that lesion disappeared spontaneously without treatment during the 2 months after biopsy.…”

“…However, neuropathologists should also take note of the opposite situation, in which demyelinating diseases resemble primary CNS lymphomas both clinically and histologically. Indeed, we experienced a difficult case of demyelinating disease that simulated primary CNS lymphoma because of prominent perivascular lymphocytes and other inflammatory cells . However, these lymphocytes did not show significant atypia or monoclonality and retrospective analysis of high elevated plasma concentrations of very long chain fatty acids confirmed the diagnosis of demyelinating lesions of adrenoleukodystrophy (Fig.…”

“…Neuroimaging thus provides crucial information to neuropathologists; however, primary CNS lymphomas should also be considered in cases showing diverse neuroimaging results. We investigated the accuracy of the clinical diagnosis of primary CNS lymphomas and our data indicated that the accuracy of intraoperative rapid diagnosis was significantly higher than that of neuroimaging diagnosis . In general, the primary treatment for primary CNS lymphomas includes a combination of chemotherapies containing high‐dose methotrexate followed by radiotherapy .…”

“…In addition, when examining intraoperative preparations, neuropathologists should note the key feature that cells from primary CNS lymphomas do not adhere to each other. In general, primary CNS lymphoma cells fragment and die easily, leaving behind cellular debris that is comprised of apoptotic cells and lymphoglandular bodies (LGB) . These LGB are small, membrane‐delimited fragments of cytoplasm that often contain a slightly more basophilic core.…”

Intraoperative squash cytology provides a qualitative intraoperative diagnosis for cases in which frozen section yields a diagnosis of equivocal brain tumour

“…We speculate that cytotechnologists treat tissue samples obtained from malignant lymphomas very carefully in squash preparations because they are very soft, applying as little pressure as possible in spreading the tissue into a thin film. In fact, there are no reports of severe crush artefacts related to the squash preparation process in cases of malignant central nervous system lymphoma . It also seems that the presence of lymphoglandular bodies in squash preparations of malignant lymphoma and of cytoplasmic fibrillary processes in squash preparations of glioma are characteristic cytological findings, although not necessarily always present, and that these features are useful in differentiating these tumours from other types of brain tumour.…”