대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Primitive Neuroectodermal Tumor (PNET, Askin Tumor)

Radiologic Findings

Posteroanterior chest radiograph shows a large mass in the left lower hemithorax with left 7th rib destruction. Contrast-enhanced CT scans show a large heterogeneously enhancing mass involving lung, pleura, and chest wall with rib destruction.

Brief Review

Askin tumors are malignant small cell tumors of neuroepithelial origin seen in childhood and adolescence, and very rarely in adults. It arises in the soft tissues of the chest wall, occasionally in bone, or, rarely, in the periphery of the lung. This neoplasm is now recognized as a type of primitive neuroectodermal tumor (PNET). Askin tumors probably develop from embryonal migrating cells of the neural crest. This neoplasm is an undifferentiated, small-round cell sarcoma and must be distinguished from other tumors that have small round cells, such as undifferentiated neuroblastoma, embryonal rhabdomyosarcoma, Ewing’s sarcoma, and lymphoma. The intrathoracic soft tissue mass, which may show calcification, can be huge with either no visible rib destruction or only focal rib lysis. Pleural effusions and hilar adenopathy may accompany by the mass.
On CT and MRI scans, Askin tumors are mostly seen as rather large, heterogeneous masses with cystic and necrotic areas, intratumoral hemorrhage and focal calcification. The prominent contrast enhancement on both CT and MRI scans reflects the increased vascularity of PNET.

References

1. Askin FB, Rosal J, Sibley RK, McAlister WH. Malignant small cell tumor of the thoracopulmonary region in childhood: a distinctive clinico-pathologic entity of uncertain histogenesis. Cancer 1979;43:2438-2451
2. Winer-Muram HT, Kauffman WM, Gronemeyer SA, Jennings SG. Primitive neuroectodermal tumors of the chest wall (Askin tumors): CT and MR findings. AJR 1993;161:265-268
3. Pickuth D, Leutloff U. Computed tomography and magnetic resonance imaging findings in primitive neuroectodermal tumours in adults. Br J Radiol 1996 Jan;69:1-5
4. Sallustio G, Pirronti T, Lasorella A, Natale L, Bray A, Marano P. Diagnostic imaging of primitive neuroectodermal tumour of the chest wall (Askin tumour). Pediatr Radiol 1998 ;28:697-702
5. Sabate JM, Franquet T, Parellada JA, Monill JM, Oliva E. Malignant neuroectodermal tumour of the chest wall (Askin tumour): CT and MR findings in eight patients. Clin Radiol 1994;49:634-638
6. Schulman H, Newman-Heinman N, Kurtzbart E, Maor E, Zirkin H, Laufer L. Thoracoabdominal peripheral primitive neuroectodermal tumors in childhood: radiological features. Eur Radiol 2000;10(10):1649-1652

Keywords

Lung, Malignant tumor, Primitive Neuroectodermal Tumor (PNET, Askin Tumor)