Ewing's tumors of the jaws.

Ewing’s tumor is a disease of children and adolescents with rare occurrence after the third decade of life. Involvement of the jaws is uncommon. The clinical and radiographic presentations are highly variable and may mimic an inflammatory lesion. An example of metastatic Ewing’ s tumor to the maxilla in a 13-year-old female is presented. A review of Ewing’s tumor of the jaws is presented with emphasis on the clinical findings, treatment, and prognosis. James EwingI initially described the primary malignant tumor of bone bearing his name in 1921. He described the disorder as a diffuse endothelioma of bone because the form of the neoplastic cells suggested an endothelial nature and because these cells rarely were found lining fine spaces which contained red blood cells. He stressed that this lesion is distinctly different from osteogenic sarcoma, since it presents different clinical and histological features and because it is sensitive to radiation. The origin of the neoplastic cells of Ewing’s tumor has been elusive. A number of sophisticated studies utilizing light microscopy, electron microscopy, cytochemistry, and cell culture techniques have failed to provide an explanation which is agreeable to all. Immature reticulum cells, 2,3 primitive myeloid cells, 4 hemangiogenic cells, 5 immature mesenchymal cells, 6"7 and histiocytic cells 7 all have been presented as the possible cell type represented by Ewing’s tumor. A hypothesis presented by Llombart-Bosch et al., 7 if true, would help explain the variety of theories on the origin of Ewing’s tumor. They suggest that the tumor is not a unique neoplasm but a heterogeneous collection of small round cell sarcomas of bone. They describe the pluripotential marrow mesenchymal cell with its ability to differentiate along fibroblastic, histiocytic, and angioblastic cell lines as the cell of origin responsible for the difficulty in deciding on a single cell of origin. The typical histologic pattern of Ewing’s tumor consists of dense collections of uniform cells which exhibit basophilic round to oval nuclei with an associated slightly granular cytoplasm and indistinct cell outlines. 8 These cells tend to aggregate into packets which are surrounded by thin strands of fibrous tissue. Reticulin staining demonstrates fibers normally present only within the fibrous septa or around blood vessels. The cellular packets are typically devoid of reticulin fibers. Periodic acid-Schiff (PAS) stain reveals the presence of glycogen in the cytoplasm of the tumor cells in more than 90% of the cases. 9 Ewing’s tumor is a disease of children and adolescents, rarely occurring after the third decade of life. 9 The disease exhibits a male predilection. 8 The tumor may occur in any bone, but it is seen predominantly in the lower extremities and pelvic girdle. 8,9 Involvement of the jaws is uncommon. In one of the larger series of Ewing’s tumor Dahlina reported only 1% of 299 cases occurred in the jaws. Clinical reports of Ewing’s tumor metastatic to the jaws also are few in number. 1° The following case describes a patient with primary Ewing’s tumor of the right pelvis with a secondary involvement of the maxilla.