We aim to present a case report of a patient with two gliomas and multiple endochondromas, consistent with Ollier disease, who was also found to have an apparent germline pathogenic IDH1 gene mutation.

The isocitrate dehydrogenase (IDH) enzyme is responsible for catalyzing the decarboxylation of isocitrate to alpha-ketoglutarate to generate NADPH in the Krebs cycle. IDH1 and 2 mutations occur in over 80% of WHO grade II/III astrocytomas, oligodendrogliomas, and oligoastrocytomas. Somatic IDH1 mutations are known to be associated with Ollier disease. IDH genotyping has the potential to be a marker for tumor characterization that could be superior to histological characterization.

A 25-year-old female with known Ollier disease since childhood and multiple enchondromas in her long bones was diagnosed with bilateral frontal lobe anaplastic oligodendroglioma, IDH1 mutant, 1p/19q codeleted in 2013. She subsequently developed rapidly growing tumors in the left frontal lobe with a different pathological profile of glioblastoma, IDH1 mutant but without the 1p/19q codeletion. Her history of Ollier disease and IDH1 mutation in two different gliomas prompted an IDH1 mutation test in blood samples, which confirmed a germline IDH1 mutation. Paired leukocyte and tumor testing identified a pathogenic (p.R132H) variant (ClinVar 156444). The patient underwent a craniotomy and resection followed by radiation with concurrent temozolomide. She is currently getting adjuvant temozolomide and has a stable disease course. 

We report a patient with a germline IDH1 mutation for Ollier disease and multiple gliomas. There have been no reports so far of Ollier disease with a germline IDH1 mutation. IDH1 testing may be indicated in patients with multiple primary IDH1 deficient brain tumors.  Moreover, IDH1 genotyping could potentially serve as a new marker for distinguishing between a primary and secondary brain tumor.