Cystic presentation of Ewing's sarcoma with indolent clinico-radiologic behaviour.

Ewing's sarcoma is a high-grade malignant primary bone tumour with aggressive clinico-radiologic features. Rarely, it exhibits a benign pattern, but presentation as a solitary bone cyst in a long bone is rather unusual. The purpose of this paper is to document such a cystic presentation with relatively benign clinico-radiologic course and to review the pertinent literature. A 27-year-old male presented with a pathologic fracture through a radiologically benign appearing solitary bone cyst in the distal tibial metaphysis. The fracture healed on conservative treatment, but the patient presented again a year later with pain and difficulty with weight bearing. Curetting and bone grafting done elsewhere was suggestive of an Ewing's sarcoma, which was later confirmed by a second biopsy. He was treated by standard neoadjuvant chemotherapy followed by wide local excision and reconstruction with an intercalary allograft. At 2 years postoperative follow-up, the patient is without any evidence of local or distant recurrence. Awareness of this atypical presentation is important because it may help in an earlier diagnosis, avoid diagnostic confusion and thus may contribute to improved survival.