We describe herein a rare case of a primary primitive neuroectodermal tumor (PNET) in the mediastinum of a 75-year-old man. Grossly, the tumor was located in the left upper anterior mediastinum. Transcutaneous fine-needle biopsy (TCNB) revealed small round-cell proliferation. The expression immunohistochemical analysis was confirmed the diagnosis of PNET. He was successfully treated with chemotherapy and is alive with no sign of recurrence for 17 months after the diagnosis. 1. Introduction PNET represents a family of tumors which shows varying degrees of neuronal differentiation most often presenting as a bone or soft tissue mass in the trunk or axial skeleton in adolescents and young adults [1]. Infrequently, PNETs have been described in other organs, such as the kidney, gonads, pancreas, and myocardium. Intrapulmonary PNET is very rare, PNET is a highly malignant neoplasm and it is composed of small, round, uniform cells [2]. Diagnosis of the tumor is confirmed using various immunohistochemical studies and detecting the presence of a translocation, t(11;22) through fluorescent in situ hybridization (FISH) [3]. PNET can be treated with various combinations of radical surgical resection, neoadjuvant and adjuvant chemotherapy, and irradiation. The chemotherapy of choice for these tumors consists of combinations of doxorubicin, ifosfamide, cyclophosphamide, and vincristine [4]. 2. Case Report A 75-year-old man was admitted to our Department of Medical Oncology because of dry cough which started 1 month ago in July 2011. Chest X-ray showed a left paramediastinal mass. Computed tomography (CT) of the chest demonstrated a 30 × 90？mm in diameter in the upper anterior mediastinal mass with pleural effusion around the left lower lobe. A diagnostic work up was started because of possible primary lung malignancy. FDG-PET-CT scan revealed intense and homogenous hypermetabolic activity at the upper anterior paramediastinal region (standardized uptake value (SUV): 7). Furthermore, there was hypermetabolic lesions at the left basal pleura which was compatible with metastases (Figure 1). Thereafter, a percutaneous needle biopsy was performed. Histopathologic examination of the biopsy specimen indicated malignant, small, round-cell tumor. Some of the cells had irregularly vacuolated cytoplasm secondary to glycogen deposition, which was positive for Periodic Acid Schiff (PAS) stain. In addition, the glycoprotein p30/32 (CD99), which is encoded by the MIC2 gene, is strongly expressed on the surface of the tumor cells (Figure 2). The chromosome rearrangement
References
[1]
Y. B. Thyavihally, H. B. Tongaonkar, S. Gupta et al., “Primitive neuroectodermal tumor of the kidney: a single institute series of 16 patients,” Urology, vol. 71, no. 2, pp. 292–296, 2008.
[2]
S. Tsuji, M. Hisaoka, Y. Morimitsu et al., “Peripheral primitive neuroectodermal tumour of the lung: report of two cases,” Histopathology, vol. 33, no. 4, pp. 369–374, 1998.
[3]
E. Cambruzzi, E. E. Guerra, H. C. Hilgert et al., “Primitive neuroectodermal tumor of the liver: a case report,” Case Reports in Medicine, vol. 2011, Article ID 748194, 4 pages, 2011.
[4]
A. Weissferdt and C. A. Moran, “Primary Pulmonary Primitive Neuroectodermal Tumor (PNET): a clinicopathological and immunohistochemical study of six cases,” Lung, vol. 190, pp. 677–683, 2012.
[5]
F. Imamura, T. Funakoshi, S. I. Nakamura, M. Mano, K. Kodama, and T. Horai, “Primary primitive neuroectodermal tumor of the lung: report of two cases,” Lung Cancer, vol. 27, no. 1, pp. 55–60, 2000.
[6]
F. J. Baumgartner, B. O. Omari, and S. W. French, “Primitive neuroectodermal tumor of the pulmonary hilum in an adult,” Annals of Thoracic Surgery, vol. 72, no. 1, pp. 285–287, 2001.
[7]
A. G. Kahn, A. Avagnina, J. Nazar, and B. Elsner, “Primitive neuroctodermal tumor of the lung,” Archives of Pathology & Laboratory Medicine, vol. 125, pp. 397–399, 2001.
[8]
Y. Mikami, M. Nakajima, H. Hashimoto et al., “Primary pulmonary primitive neuroectodermal tumor (PNET). A case report,” Pathology Research and Practice, vol. 197, no. 2, pp. 113–119, 2001.
[9]
D. Takahashi, J. Nagayama, Y. Nagatoshi et al., “Primary Ewing's sarcoma family tumors of the lung—a case report and review of the literature,” Japanese Journal of Clinical Oncology, vol. 37, no. 11, pp. 874–877, 2007.
[10]
A. Demir, M. Z. Gunluoglu, N. Dagoglu et al., “Surgical treatment and prognosis of primitive neuroectodermal tumors of the thorax,” Journal of Thoracic Oncology, vol. 4, no. 2, pp. 185–192, 2009.
[11]
K. Hancorn, A. Sharma, and M. Shackcloth, “Primary extraskeletal Ewing's sarcoma of the lung,” Interactive Cardiovascular and Thoracic Surgery, vol. 10, no. 5, pp. 803–804, 2010.
[12]
T. Takeuchi, H. Iwasaki, Y. Ohjimi et al., “Renal primitive neuroectodermal tumor: an immunohistochemical and cytogenetic analysis,” Pathology International, vol. 46, no. 4, pp. 292–297, 1996.
[13]
F. B. Askin, J. Rosai, R. K. Sibley, L. P. Dehner, and W. H. Mc Alister, “Malignant small cell tumor of the thoracopulmonary region in childhood. A distinctive clinicopathologic entity of uncertain histogenesis,” Cancer, vol. 43, no. 6, pp. 2438–2451, 1979.
[14]
C. F. Stephenson, J. A. Bridge, and A. A. Sandberg, “Cytogenetic and pathologic analysis of Ewing’s sarcoma and neuroectodermal tumors,” Human Pathology, vol. 23, pp. 1270–1277, 1992.
[15]
T. V. Colby, M. N. Koss, and W. D. Travis, Tumors of the Lower Respiratory Tract (Atlas of Tumor Pathology, 3rd Series, Fascicle 13), AFIP, Washington, DC, USA, 1995.
[16]
M. A. Applebaum, J. Worch, R. Goldsby et al., “Clinicalfeaturesandoutcomes in patients with extraskeletal Ewingsarcoma,” Cancer, vol. 117, pp. 3027–3032, 2011.
