Metastasis of anaplastic oligodendroglioma to the bone marrow is very rare, and only a few cases have been reported to date.1–3 No precise epidemiologic data on the incidence of anaplastic oligodendrogliomas are available. In a series of 285 supratentorial anaplastic gliomas in adults, 10 tumors were classified as anaplastic oligodendrogliomas. These 10 tumors accounted for 3.5% of the adult supratentorial malignant gliomas in the series.
A 33-year-old white man visited the local emergency room for hip pain after a fall. Radiographs of the lumbosacral spine and left hip, magnetic resonance imaging of the brain, and computed tomography of the chest revealed no significant findings. The patient had a history of anaplastic oligodendroglioma treated with surgical resection, which was followed by radiation and chemotherapy 3 years earlier at a different health care center. Two months later, he visited the emergency room for a second time with the complaint of black tarry stools, as well as persistent hip pain. He was noted to have normocytic anemia, thrombocytopenia, and leukoerythroblastosis. A magnetic resonance image of the lumbar spine without contrast was performed and revealed diffuse abnormal signal in the lumbar vertebral bodies, suggestive of a marrow-replacing process.
Bone marrow aspirate and biopsy were requested. A bone marrow aspirate could not be obtained (dry tap). Touch preparations of the bone marrow biopsy revealed a few large nuclei devoid of cytoplasm, but were hypocellular and suboptimal for interpretation. The bone marrow biopsy showed atypical cells in a loosely fibrotic marrow. These cells had a moderate nucleus to cytoplasmic ratio, granular eosinophilic cytoplasm, and eccentrically located nuclei (Figure 1). In addition, immunohistochemical stains were positive for glial fibrillary acidic protein (Figure 2) and S100, but were negative for CD34, CD45, cytokeratin, and myeloperoxidase. A review of the original histologic slides from the previous institution revealed a tumor with similar morphology at both lower (Figure 3, A) and higher magnifications (Figure 3, B).
Oligodendrogliomas are uncommon brain tumors and rarely metastasize. Theories as to why metastasis is rare in patients with oligodendrogliomas include the presence of the blood-brain barrier, absence of lymphatics in the brain, and short survival of the patients. Multiple surgeries, delayed surgery, long survival, and shunts are thought to be associated with increased chance of metastasis. The most commonly reported sites of metastasis are bone (75%), cervical lymph nodes (50%), and lung or pleura (33%).1 Newman et al reported a case of metastatic oligodendroglioma to bone marrow that presented with leukoerythroblastic anemia.1 A review of the literature demonstrated 18 documented cases of anaplastic oligodendroglioma; these tumors showed a high proportion of bone marrow metastasis, and 4 exhibited diffuse marrow involvement with blood dyscrasia.2
Cytologic features of metastatic anaplastic oligodendroglioma are potentially misleading, as they can mimic acute leukemia on bone marrow touch preparations.3 In our case, the differential diagnosis included secondary leukemia due to previous chemotherapy. Therefore, bone marrow examination with immunohistochemical stains was of paramount importance in making a correct diagnosis.
In summary, extraneural metastasis of anaplastic oligodendroglioma is rare, and only a few cases of bone marrow involvement have been reported. The differential diagnosis, given the clinical presentation in a patient with a history of anaplastic oligodendroglioma, includes (1) bone marrow involvement by anaplastic oligodendroglioma, (2) secondary leukemia due to previous chemotherapy, and (3) a second disseminated primary tumor. For these reasons, bone marrow aspirate and biopsy with complete immunohistochemical evaluation were warranted.
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The authors have no relevant financial interest in the products or companies described in this article.