ID #337 Peripheral Primitive Neuroectodermal Tumor in a Pediatric Patient

Abstract

Primitive neuroectodermal tumors (PNET) are rare and highly aggressive central nervous system tumors which were reclassified by WHO in 2016 to be a subtype of embryonal tumors. There are numerous publications of patients initially diagnosed with testicular teratomas that have relapsed with PNETs. Less common in the literature are ovarian teratomas which relapse to PNETs, with only a handful of cases, with this presentation reported.

We present a case report for a patient who at twelve years old had gross total resection of an ovarian teratoma. On further pathology review, inside the teratoma was malignant embryonal neuronal tissue. Eight months later, she was found to have a large left ischium mass with avid lesions in her lumbar and sacral vertebrae, and biopsy confirmed PNET. She started chemotherapy with ifosfamide, etoposide, vincristine, cyclophosphamide, and doxorubicin with negative PET results at the end of Induction. She is currently receiving consolidation chemotherapy. This combination regimen showed response in patients from the CCG7942 clinical trial on the intensified arm.

PNET tumors are typically treated with combination chemotherapy such as those used for this patient, with radiation, surgical resection, and targeted therapies depending on genetic abnormalities. There have been Children’s Oncology Group studies assessing the effect of temozolomide/irinotecan/bevacizumab, autologous stem cell rescue, and cisplatin/cyclophosphamide/vincristine for PNETs. Long term survival rates for PNETs are still quite poor, with no standardized treatment protocol particularly for peripheral PNETs. Advances in molecular characterization and evaluation of these rare teratomas leading to peripheral PNET would be useful in risk assessment and treatment planning. Additional research is needed for effective treatment of these rare aggressive embryonal tumors.