Metastatic anaplastic oligodendroglioma simulating acute leukemia. A case report

BACKGROUND: Anaplastic oligodendroglioma (OG) is an uncommon tumor that rarely metastasizes outside the central nervous system. Spread to the bone marrow (BM) is so rare that when it occurs in the course of follow-up of a case of OG, a disseminated second primary tumor may be a more likely possibility unless BM examination provides evidence to the contrary. Potentially misleading cytologic features of metastatic anaplastic OG can be seen in a BM touch preparation. CASE: A 50-year-old man had undergone left frontal lobectomy in September 1999 for anaplastic OG and presented seven months later with evidence, on BM scan, of focal abnormal uptake at multiple sites. Bone marrow biopsy confirmed OG secondaries, which, on the touch preparation, appeared not only in clusters but also as single cells, simulating acute leukemia. CONCLUSION: The morphology of anaplastic OG metastatic to BM simulates acute leukemia, as seen on the BM touch preparation. This is relevant particularly in the context of anaplastic OG on follow-up. This diagnostic pitfall can be heightened if a BM aspirate rather than biopsy is performed. Metastatic OG can be added to the list of tumors that metastasize to BM as single cells.