Chondroblastoma in the long bone diaphysis: a report of two cases with literature review
A 21-year-old woman was admitted because of a fixed palpable mass in the right humerus over 1 month. On physical examination, an approximately 2 cm, firm, fixed mass was noted in the media of the brachium. The overlying skin was normal and there was no sensory or motor deficit. There was no evidence of soft tissue mass or concurrent illness. A plain radiograph showed an osseous protuberance in the diaphysis of the right humerus (). CT scans demonstrated an ossifying bony protuberance arising from the cortex. There was no evidence of extension to the adjacent soft tissue (). A benign lesion was suspected. En bloc resection from the bottom of the protuberance, including some normal cortex, was performed. The final pathologic diagnosis was chondroblastoma, with tumor cells positive for S-100 (). After the operation, the function of the arm was excellent, and there was no recurrence at the 48-month follow-up.\nThese two atypical cases indicate that, except for the distinctive site of long bone diaphysis, which made diagnosis difficult, the patients' ages, symptoms, X-ray and CT images, treatments, and prognosis were in accordance with typical lesions in the epiphysis and metaphysis.