Chondroblastoma in the long bone diaphysis: a report of two cases with literature review
A 15-year-old boy was admitted to hospital because of persistent pain in the left leg for 2 weeks. Physical examination revealed a tender swelling and pressing pain in the media region of the left leg. There was no evidence of soft tissue mass or concurrent illness. The patient had no history of trauma or irradiation in this region. A plain radiograph showed a well-defined lytic defect, measuring 5-6 cm in diameter in the diaphysis of the left tibia (). CT scans demonstrated an area of extensive lytic bony destruction with little discernible residual cortex and no significant periosteal reaction. The margins were well delineated, and there was no matrix formation within the lesion (). T1-weighted MRI showed an irregular, slightly low signal intensity mass with central nodularity (), which exhibited heterogeneity and slightly high signal intensity on T2-weighted images (). The bone emission computed tomography (ECT) showed clearly defined radiopharmaceutical uptake in the media part of the left leg (). A benign osseous lesion, such as non-ossifying fibroma, fibrous dysplasia, and eosinophilic granuloma, was suspected because of the less aggressive radiological features. Examination of frozen sections was performed during the operation and the pathologic diagnosis was chondroblastoma. Curettage and bone grafting were performed with subsequent cessation of pain. The final pathologic diagnosis was consistent with the frozen section diagnosis (). Postoperatively, the function of the leg was excellent and no recurrence was found at the 60-month follow-up.