10. DISSEMINATED OLIGODENDROGLIAL-LIKE LEPTOMENINGEAL TUMOUR OF CHILDHOOD: A CASE SERIES OF A RARE AND NEWLY DESCRIBED ENTITY. (February 2015) - D'Arcy, C. E.
Abstract : Background: Disseminated oligodendroglial-like leptomeningeal tumour of childhood (DOLTC) is a newly described, rare paediatric neoplasm characterised by dissemination of oligodendroglial-like neoplastic cells in the central nervous system surface and leptomeninges. Aim: To compare the clinicopathological features of cases of DOLTC diagnosed and treated at the Royal Children's Hospital, Melbourne, with those previously reported. Methods: A retrospective review was performed of all cases of DOLTC diagnosed and treated at the Royal Children's Hospital, Melbourne. Results: Three cases of DOLTC were identified, two were female and one male. The age range at presentation was 3–14 years. Presentating symptoms included acute unilateral cranial nerve palsy, symptoms of raised intracranial pressure and of spinal cord compression. MRI brain and spine revealed hydrocephalus and marked basal brain and extensive spinal leptomeningeal enhancement in all cases, and an intramedullary C6–7 enhancing cervical cord lesion in two cases. In all three cases meningeal biopsy revealed infiltration of leptomeninges by sheets of round cells with small regular nuclei and clear cytoplasm which were GFAP and synaptophysin positive. One case had focal histological features resembling pilocytic atrocytoma and in another case the infiltrating round cells were scattered and subtle, and detected only after examining multiple levels. BRAF analysis was performed on two cases and revealed a BRAF-KIAA1549 fusion in one case. Conclusion: Given the sometimes subtle histological features the diagnosis of DOLTC is aided by immunohistochemistry. This is the first series in which BRAF analysis was performed in DOLTC and the presence of the BRAF fusion (f BRAF ) in one case extends the spectrum of tumour types associated with f BRAF to include this rare entity.