Hindawi Publishing Corporation Case Reports in Medicine Volume 2011, Article ID 748194, 4 pages doi:10.1155/2011/748194 Case Report Primitive Neuroectodermal Tumor of the Liver: A Case Report Eduardo Cambruzzi, 1 Enilde Eloena Guerra, 2 Hamilton Cardoso Hilgert, 2 Herbert Jorge Schmitz, 2 Vin´ ıcius Lopes Silva, 2 Daniel Marini Milani, 2 Ricardo Pedrini Cruz, 2 and Raul Pruinelli 2 1 Department of Pathology, Nossa Senhora da Conceic ¸˜ ao Hospital, Porto Alegre, Rio Grande do Sul, Brazil 2 Department of Surgery, Nossa Senhora da Conceic ¸˜ ao Hospital, Porto Alegre, Rio Grande do Sul, Brazil Correspondence should be addressed to Eduardo Cambruzzi, dudacambruzzi@yahoo.com.br Received 5 September 2011; Revised 26 September 2011; Accepted 29 September 2011 Academic Editor: Estella M. Matutes Copyright © 2011 Eduardo Cambruzzi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Primary liver sarcomas represent a rare group of neoplasias, with angiosarcoma being the most common histological type. Primi- tive neuroectodermal tumor (PNET) represents a high malignant neoplasia that usually affects the central nervous system and soft tissues. An 18-year-old male patient was admitted with clinical complains of pain in the right upper abdominal quadrant. The clin- ical evaluation revealed a solid mass in the right hepatic lobe. On the gross examination of the resected liver specimen, the right lobe of the liver was replaced by a yellow-red solid mass measuring 21cm in its largest dimension. On the histopathology, a tu- mor composed of small round blue cells with little cytoplasm and round nuclei was identified. The lesion revealed positive immu- noexpression for vimentin and CD99 and negative immunostaining for desmin, CD45, cytokeratin, and neuroblastoma protein, suggesting, then, the diagnosis of PNET. Although it is an unusual tumor, it should be considered in the differential diagnosis of liv- er masses, especially in young patients. 1. Introduction Liver neoplastic lesions include many different histological types of primary benign and malignant masses and high rates of metastatic processes. Primary tumors can be solid or cystic and can arise from hepatocyte, bile duct epithelium, neu- roendocrine cells, mesenchymal cells, and, rarely, from heter- otopic tissues [1, 2]. Hepatoblastoma and mesenchymal ha- martoma are usually found in the pediatric population. He- patocellular carcinoma represent the single most common histologic type of malignant epithelial tumors of the liver (about 85–90%), being frequently associated to cirrhosis and chronic viral hepatitis. Primary hepatic sarcomas are exceed- ingly unusual, accounting for only 1% to 2% of all malignant tumors arising in the liver, with angiosarcoma and undiffer- entiated sarcoma being the most common histologic types [1, 2]. PNET represents a family of tumors which shows varying degrees of neuronal differentiation with an Ewing’s sarcoma gene rearrangement, most often as a consequence of a t (11; 22) (q24; q12) chromosomal translocation. PNET is a high- ly malignant neoplasm most commonly involving the central nervous and skeletal system, and it is composed of small, round, uniform cells. Because of the undifferentiated appear- ance of the tumor cells, it looks as if the original cell might be an undifferentiated mesenchymal cell [3–5]. Herein, the au- thors report a case of PNET arising in the liver and review the morphologic and immunohistochemical findings of this tu- mor in a rare topography. 2. Case Report An 18-year-old male African descent patient was admitted complaining of pain in the right upper quadrant of the ab- dominal region for the last 3 months. The physical exam- ination revealed a firm, solid mass with an irregular lower border and mild tenderness in the liver topography. Abdom- inal ultrasonography and computed tomography (CT) scans showed a solid mass in the right hepatic lobe, measuring 21 cm in its largest diameter, with possible colon and right kidney invasion, and vena cava compression (Figure 1). Pre- operative right hepatic artery embolization was performed.