RARE-63. MULTICENTRIC GLIOMA IN OLLIER DISEASE: A CASE REPORT AND REVIEW OF THE LITERATURE

To discuss a case of multicentric glioma in a patient with Ollier disease (OD) and review the literature surrounding this association. OD is a subtype of multiple enchondromatosis, characterized by hamartomatous proliferation of chondrocytes in long bones. Extra-osseous tumors have been increasingly reported in this condition, with a particular predisposition towards gliomagenesis. Presentation of an illustrative case and literature review of gliomas in patients with OD. A 26-year-old male with OD initially presented at age 15 years with a left skull base chondroma. This dedifferentiated to a chondrosarcoma, requiring resection and radiation therapy. At age 22 years, bifrontal MRI changes consistent with low-grade glioma were identified. Biopsy of the right frontal lesion demonstrated oligodendroglioma, IDH-mutant, 1p/19q-codeleted, WHO grade II. Despite adjuvant chemotherapy with temozolomide (TMZ), there was radiographic progression after treatment discontinuation. TMZ therapy was resumed; however, radiographic progression of the left frontal lesion led to surgical resection. A histologic diagnosis of anaplastic oligodendroglioma, WHO grade III, was rendered. Despite radiation therapy and adjuvant procarbazine and lomustine, the left frontal lesion demonstrated enlargement and high-grade features; repeat resection yielded an integrated diagnosis of glioblastoma, IDH-mutant, negative for 1p/19q codeletion (1p loss, 19q intact). This case reinforces the association between OD and gliomagenesis. Additionally, multicentric glioma in OD is exceptional. The mutant isocitrate dehydrogenase (IDH) 1 pathway in this patient’s gliomas may represent the driving oncogenic pathway for his condition. Increasing evidence supports the concept of somatic heterozygous mutations of IDH1 and IDH2 playing a central role in tumorigenesis in OD, with this aberrant pathway contributing to the development of both mesenchymal and glial tumors. Further characterization of gliomas in OD is essential to our understanding of their pathogenesis, and may illuminate potential therapeutic avenues for glioma arising in the setting of OD.