Intracranial Peripheral-Type Primitive Neuroectodermal Tumor -Case Report-

Abstract

A 15-year-old man presented with headache. Magnetic resonance (MR) imaging revealed a large extraaxial tumor with cyst at the right frontotemporal region. The solid part of the tumor was homogeneously enhanced on T 1 -weighted MR imaging after injection of gadolinium. Digital subtraction angiography of the external carotid artery revealed sunburst appearance corresponding to the tumor, which was fed by the right middle meningeal artery. His headache worsened and computed tomography revealed enlargement of the tumor and intracystic hemorrhage, so emergent operation was performed. At surgery, the tumor strongly adhered to the dural membrane, and was obviously extraaxial. The tumor and cyst were gross totally removed. The attachment site at the dura mater was resected. Histological examination showed solid growth of small round cells with uniform round nuclei and minimal cytoplasm. Immunohistochemical staining showed the cells were positive for MIC-2 (CD99). The MIB-1 labeling index was 53%. The histological diagnosis was peripheral-type primitive neuroectodermal tumor (pPNET). Following surgery, radiation therapy and chemotherapy were given. Ewing's sarcoma and pPNET form a family of small round cell tumors arising in the bone or soft tissue. MIC-2 is a useful marker in the differential diagnosis. Good prognosis may be attained if complete surgical excision of intracranial pPNET is achieved.

The Evaluation of CD99 Immunoreactivity and EWS/FLI1 Translocation by Fluorescence in situ Hybridization in Central PNETs and Ewing’s Sarcoma Family of Tumors

“…(Table 2) [26]. Immunohistochemistry for CD99 is usually detected in ESFTs but is not detected in cPNETs [1,16,[21][22][23][24][25]. In our study we found CD99 positivity in 10 of 11ESFT cases (90%), and 2 of 7 cPNET cases were detected CD99 immunoreactivity, similar to the literature.…”

“…Although extremely rare cases of olfactory neuroblastoma, small cell osteosarcoma, mesenchymal chondrosarcoma, polyphenotypic round cell tumor, desmoplastic small round cell tumor, neuroblastoma and rhabdomyosarcoma have been reported to contain either EWS/FLI1 or EWS/ERG fusion genes, the identification of these translocations is for the most part regarded as highly specific to ESFTs and is increasingly recognized as the "gold standard" for diagnosis [3,4,13,[17][18][19][20]. In contrast, such translocations are not found in cPNETs [1,2,16,[21][22][23][24][25]. Thorner et al reported that identification of the t(l1;22) (q24; q12) by cytogenetics should not be taken as absolute proof of a diagnosis of ESFTs in the absence of confirmatory histology to include positive staining for MIC2 [28].…”

“…Recently, these tumors were divided into central PNET (cPNET) such as medulloblastoma and supratentorial PNET, originating in the central or sympathetic nervous system, and peripheral PNET (pPNET), originating in the soft tissue or bone [1,2]. Although Ewing's sarcoma and pPNET were orginally regarded as totally separate entities, it has subsequently been established that both Ewing's sarcoma and pPNET share a balanced translocation in over 90% of cases [t (11;22)(q12;q24)] and they are now almost universally regarded as ends of a common histologic spectrum, known as the "Ewing's Sarcoma Family of Tumors (ESFTs)" [3,4].…”

Central Nervous System Primitive Neuroectodermal Tumor of Spinal Cord Developing 20 Years After Curative Treatment of Pineal Tumor -Case Report-

“…In the neurosurgical field, EWS/pPNETs occasionally occur in the meninges of the cranial vault, epidural space of the spinal canal, and cauda equina. 8,13) CD99 is a 30 or 32 kDa cell surface glycoprotein derived from the MIC2 gene. This molecule was initially isolated as an EWS antigen and so expression was considered pathognomonic for EWS/pPNET.…”

Fine Needle Aspiration Cytology of Intracranial Peripheral-Type Primitive Neuroectodermal Tumor

“…Intracranial occurrence of pPNET is extremely rare, and only a few cases have been reported to date. [3][4][5] We report a 16-year-old boy who presented with headache and gradual left-sided hearing loss.…”