RARE-05. ANAPLASTIC ASTROCYTOMA AND OLIGODENDROGLIOMA PRESENTING AS SIMULTANEOUS PRIMARY BRAIN TUMORS IN A PEDIATRIC PATIENT: THE FIRST KNOWN REPORT OF A RARE CONDITION

Abstract

Abstract Multiple metastatic brain tumors and multiple histologically identical primary brain tumors have been reported in adults and children. The concurrent presence of multiple histologically distinct primary brain tumors is rare without prior chemotherapy, radiotherapy, or phacomatosis. Exceedingly rare are simultaneous histologically distinct primary brain tumors in children without therapeutic or genetic predisposition, with only five previously reported cases. Gliomas are the most common primary brain tumor in adults and children. Gliomas encompass a heterogenous group characterized by astrocytic, oliogodendroglial, and ependymomal histology, further subdivided into pathologic World Health Organization (WHO) grades I to IV. In children, grade I astrocytomas are the most common, with grade III astrocytomas (anaplastic astrocytomas) and oligodendrogliomas being rare. We report a case of simultaneous anaplastic astrocytoma and grade II oligodendroglioma in a pediatric patient. A previously healthy 6-year-old female presented with persistent headaches. Initial magnetic resonance imaging (MRI) demonstrated non-enhancing right frontal lobe and left peri-thalamic lesions without mass affect. Serial MRIs showed progression of both lesions, prompting frontal lobe biopsy, which revealed a grade II oligodendroglioma. The patient was started on standard low-grade glioma chemotherapy, which was stopped due to an allergic reaction. Following chemotherapy cessation, both lesions increased in size, and the peri-thalamic lesion demonstrated new heterogenous enhancement. The patient underwent gross-total resection of the peri-thalamic lesion and repeat biopsy of the frontal lobe lesion. Pathology confirmed the frontal lobe lesion to be a grade II oligodendroglioma and revealed the peri-thalamic lesion to be an anaplastic astrocytoma. The tumors were additionally proven molecularly distinct. The patient responded well to cranial radiotherapy and standard high-grade glioma chemotherapy. To the best of the authors’ knowledge, this is the first case of simultaneous anaplastic astrocytoma and oligodendroglioma in a child, increasingly unique given the histological and molecular rarity of the tumors in pediatric patients.