Anaplastic pleomorphic xanthoastrocytoma

Abstract

Objective To investigate the clinicopathological features, immune phenotype and gene mutation characteristics, and diagnosis or differential diagnosis of anaplastic pleomorphic xanthoastrocytoma (PXA).  Methods and Results A 11 - year- old male patient presented with more than half month of headache, and left upper limb weakness. Cranial CT and MRI revealed a large space-occupying lesion in the right parietal lobe and basal ganglia which was suggested as glioma. During operation the tumor was examined. It was a cystic-solid lesion. The solid part was soft and greyish yellow with rich blood supply and without membrane, and the boundary was clear. Intraoperative freezing pathologic examination showed the tumor was a low grade glioma. The right parietal glioma was completely removed piece by piece under the microscopy. Histologically, the tumor cells were polymorphism, including spindle or round astrocytes, monocytes and multinuclear tumor giant cells. Mitoses were rarely seen. Differentiation of mature neuronal cells or ganglion cells with lymphocyte infiltration were seen in focal region. In some regions, tumor cells were anaplastic, and cellularity were increased. Atypical round or spindle cells were seen, and atypical mitoses > 5/10 high power field (HPF) were found.  icrovascular proliferation, perivascular pseudorosettes and localized necrosis were also evident. Immunohistochemically, tumor cells were positive for glial fibrillary acidic protein (GFAP), BRAF V600E, S-100 protein (S-100), CD34, synaptophysin (Syn), non- phosphorylation neurofilament heauy chain SMI- 32 and P53, but negative for isocitrate dehydrogenase 1(IDH1), neurofilament protein (NF) and epithelial membrane antigen (EMA). Ki - 67 labeling index was about 3% in low grade tumor cells, while Ki-67 labeling index was about 30% in high grade tumor cells. In reticular fibre tissue staining, a lot of reticular fibre tissue were seen. BRAF V600E heterozygous mutation c.1799A > T was detected by Sanger sequencing.  Conclusions Anaplastic PXA in grade Ⅲ is defined as mitoses > 5/10 HPF in World Health Organization (WHO) classification of tumors of the central neuvous system, 2016. Its prognosis is worse than grade Ⅱ tumor. The differential diagnosis from glioblastoma (GBM), pilocytic astrocytoma (PA) and ganglioglioma (GG) should be kept in mind, because all of them having some overlaps in clinicopathological presentations, imaging manifestation, immunophenotype features and genetic mutation, but quite different in their biological behavior, treatment and prognosis.

DOI: 10.3969/j.issn.1672-6731.2017.08.011