Tehran University of Medical Sciences International Journal of Hematology-Oncology and Stem Cell Research 2008-2207 12 4 2018 07 11 264 271 EN Prita Pradhan Department of Pathology, Jawaharlal Institute of Post graduate Medical Education and Research, Puducherry, India Biswajit Dey Department of Pathology, Andaman and Nicobar Islands Institute of Medical Sciences, Port Blair, India Bheemanathi Srinivas Department of Urology, Jawaharlal Institute of Postgraduate Medical Education and Reserach, Puducherry, India Sajini Jacob Department of Pathology, Jawaharlal Institute of Post graduate Medical Education and Research, Puducherry, India Roopesh Kumar Rathakrishnan Department of Neurosurgery, Jawaharlal Institute of Postgraduate Medical Education and Research, Pundicherry, India 2017 09 20 2018 07 11 Background: Pleomorphic xanthoastrocytoma is a rare tumour of children and young adults, particularly for those with features of anaplasia. Materials and Methods: This retrospective study comprises five cases of anaplastic pleomorphic xanthoastrocytomas diagnosed over a period of 4 years in a tertiary care institute.  A detailed linicopathological and immunohistochemical profile of the tumours were noted from the hospital database. Results: Five cases of anaplastic pleomorphic xanthoastrocytomas were evaluated for their clinicoradiological, histomorphological as well as immunohistochemical findings, which included 3 females and 2 males, with age range of 11-40 years and a mean age at presentation of 22 years. Histologically a solid cystic biphasic tumour with moderate to high cellularity, spindled pleomorphic astrocytes, hyperchromatic nuclei showing moderate to marked atypia, intranuclear inclusions, ≥5 mitoses per 10 high power fields, with evidence of necrosis and atypical mitoses was noted. One of the cases showed transformation into glioblastoma with evidence of spinal metastasis on follow-up. The tumours expressed both glial as well as neuronal markers with expression of CD34 with increased Ki 67 ranging between 5-20%. Conclusion: It was concluded that PXA, a low-grade glioneuronal tumour, can show odd site presentation, marked pleomorphism, increased mitosis, atypical mitoses and increased Ki 67 when associated with features of anaplasia. An appropriate panel of immunohistochemical markers in conjunction with a detailed evaluation of histomorphological features and clinicoradiological information are useful for its diagnosis. https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/view/861 https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/download/861/760