A Case of Ewing' s Sarcoma Arising in the Distal Phalanx / 대한피부과학회지

ABSTRACT

Ewing's sarcoma is a highly malignant, small, round cell tumor that usually affects long bones. The acral part of the extremities is a very rare primary site for this neo plasm. A fifteen-year-old girl was seen for a lobulated, dome-shaped, 2.7cm diameter, denuded mass on the distal phalanx of the right middle finger which had increased in size over a 14-month period. The radiological featuies of the hand showed a cortical brick of distal phalanx and surrounding soft tissue mass. Histologically, the biopsy specimen showed sheets of small round to oval cells with scanty cytoplasm, that were closely packed and separated into lobules by trands of fibrous tissue. A periodic acid-Schiff stain demonsirated glycogen in the cytoplasm of the tumor cells. Electron microscopy showed large aggregates of glycogen in the cytoplasm of the neoaplastic cells. Immunohistochemical stains revealed positive staining for vimentin, glial fibrillary acid potein, and neuron specific enolase, stains for S-100, Factor VIII, and cytokeratin were negative.