Pilocytic astrocytoma with angiocentric arrangement: a case report and literature review

Abstract

Background Pilocytic astrocytoma (PA) is a low⁃grade glioma that occurs mainly in the cerebellum of children and young adults. This article is to report a rare case of PA with angiocentric arrangement in the supratentorial region of a 28-year-old male. The pathomorphism of this tumor is different from that of typical PA, since most tumor cells grow in single layer around the hyalinized degenerative vessels, that is to say, angiocentric pattern. This paper aims to discuss the clinical, imaging and pathological features of PA with angiocentric arrangement and clinicopathological differentiations from relevant tumors, so as to improve the ability of diagnosing and differentiating this kind of tumor. Methods and Results A 28-year-old male with no significant past history presented with repeated grand mal seizures and did not recover in the treatment with antiepileptic drugs. Physical and neurological examinations were normal. Electroencephalography (EEG) found no typical epileptic wave or focal δ wave. CT and MRI showed a superficial cystic mass with a mural nodule and clear boundary in the left frontal cortex. During the resection of the tumor, the lesion was identified as cystic structure on the surface and solid structure within the cyst wall. Optical microscopy findings revealed that tumour cells with round or oval nuclei and cytoplasm showing slender hair-like protuberance of both ends were arranged in single layer around hyalinized blood vessels. Some tumor cells with fusiform nuclei showed compact fascicles or loose stellate reticulum. Rosenthal fibers and eosinophilic granular bodies were occasionally seen. According to immunohistochemical staining, the tumor cells were diffusely positive for glial fibrillary acidic protein (GFAP), Vimentin (Vim), S-100 protein (S-100), Nestin, CD56, and focally positive for Olig2, while the tumor cells were negative for epithelial membrane antigen (EMA), isocitrate dehydrogenase 1 (IDH1), P53, neuronal nuclei antigen (NeuN), neurofilament protein (NFP), synaptophysin (Syn) and CD34. The overall MIB-1 labeling index was 1%. According to these findings, the tumor was diagnosed as PA with angiocentric arrangement in the left frontal lobe (WHO Grade Ⅰ). The patient was not given further treatment including radiotherapy or chemotherapy after surgery. One year follow-up showed no onset of seizures or tumor recurrence. Conclusion This is the first case report of a cerebrellum PA with extensive angiocentric arrangement in an adult. According to the clinical and histomorphological (including the angiocentric arrangement) features, the differential diagnosis should include pilomyxoid astrocytoma, astroblastoma, angiocentric glioma, cortical ependymoma and papillary glioneuronal tumor.