PNR-05PRIMITIVE MYXOID MESENCHYMAL TUMOUR OF INFANCY – A CASE OF EARLY CHEMOTHERAPY-RESPONSIVENESS AND REVIEW OF THE LITERATURE

Abstract

PNR-05. PRIMITIVE MYXOID MESENCHYMAL TUMOUR OF INFANCY – A CASE OF EARLY CHEMOTHERAPYRESPONSIVENESS AND REVIEW OF THE LITERATURE Charlotte Burns1, Juliet Clayton2, Jessica Ng3, and Jordan Hansford1; The Children’s Cancer Centre, The Royal Children’s Hospital, Melbourne, Australia; The Department of Neurosurgery, The Royal Children’s Hospital, Melbourne, Australia; The Department of Anatomical Pathology, The Royal Children’s Hospital, Melbourne, Australia Primitive myxoid mesenchymal tumour of infancy (PMMTI) is a newly described mesenchymal tumour occurring within the first year and with a predilection for deep soft tissue around the spinal cord. Histologically characterised by proliferation of primitive immature mesenchymal cells and distinctive myxoid background, it is rare with less than twenty reported cases. Complete surgical resection provides optimal disease control, as tumours are locally aggressive and recur early. Rarely, metastases or transformation to higher-grade lesions has been observed. Systemic therapy has added little value to date. We presentaneonatewith PMMTI andanearly response tochemotherapy.A term neonate admitted at twenty-one days old with bronchiolitis was noted to have progressive lower limb weakness, urinary retention and reduced anal tone. MRI spine showed an enhancing soft tissue mass within the spinal canal extending fromL1-L5. Completemacroscopic surgical resectionwasperformed. Histologywas consistentwith PMMTI. Within threemonths, progressiveneurological deficits recurred. Repeat MRI revealed unresectable, extensive local recurrence with intraand extra-spinal components and biopsy confirmed identical histology. With limited therapeutic options available, chemotherapy was initiated (ifosfamide, carboplatin and etoposide, followed by vincristine, actinomycin, cyclophosphamide and doxorubicin). Therewasmarked clinical improvement after one cycle and 35% tumour volume reduction on MRI after two. Chemotherapy-responsiveness to this extent has not been documented to our knowledge. We present a case of PMMTI presenting typically, but with an early response to aggressive sarcoma-based chemotherapy. This treatment could be considered for unresectable PMMTI, an increasingly recognised entity, in the future. Neuro-Oncology 18:iii7–iii15, 2016. doi:10.1093/neuonc/now067.5 #The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.