Primary central nervous system primitive neuroectodermal tumors (CNS-PNETs) of the spinal cord in children: four cases from the German HIT database with a critical review of the literature

Approximately 30-50% of patients with intracranial primitive neuroectodermal tumors (PNETs) of the central nervous system (CNS) develop spinal metastases. In contrast, primary spinal CNS-PNETs are extremely uncommon. The database and study records of the German/Austrian brain tumor trials HIT 91, HIT SKK 92, and HIT 2000 were retrospectively reviewed to describe clinical features, treatment modalities, and outcome of children with primary CNS-PNETs of the spinal cord who were registered as observational patients. Out of 1,248 patients with medulloblastomas or CNS-PNETs registered in the HIT database four patients (female, n = 3) with primary CNS-PNETs of the spinal cord were identified. Age at diagnosis was 10, 16, 23, and 174 months. Location of primary tumors was medulla oblongata-T3, C2-T1, T10-L2, T7-T10. Two patients had metastatic disease at diagnosis. Complete and incomplete resection was performed in one patient each, whereas two patients underwent a biopsy only. Two patients received chemotherapy only, in accordance with the HIT 91 trial (sandwich chemotherapy arm). They developed disease progression and died six months after diagnosis. One patient was given chemotherapy in accordance with the HIT 2000 trial followed by craniospinal radiotherapy and four courses of maintenance chemotherapy. The patient is in complete remission almost four years after diagnosis. The fourth patient developed disease progression while receiving induction chemotherapy. Hence, chemotherapy was switched to a modified Head Start protocol. After three cycles he underwent double autologous stem cell transplantation and craniospinal irradiation. Forty months after diagnosis the patient is alive and well, but surveillance MRIs still show nodular enhancing lesions in the area of the primary tumor and intracranial meningeal enhancement. Primary CNS-PNETs of the spinal cord probably require multimodal treatment including radiotherapy to achieve sustained tumor control.