Non-ossifying fibroma of bone (NOF) is a common entity, more frequently found in male children and consisting of a solitary eccentric, lytic expanded lesion in the metaphysis of a long bone. The disorder is benign and most often asymptomatic but may result in a fracture requiring therapy. Of some importance is to distinguish NOF from another very similar but smaller lesion, fibrous cortical defect, which is almost always asymptomatic and eccentrically located. Even more striking is a very rarely encountered lesion known as Jaffe-Campanacci syndrome, which also occurs in children who present with typical non-ossifying fibromatous tumors but in multiple sites. In addition, these patients have some systemic and dermal findings resembling those seen in patients with Type 1 neurofibromatosis.

Objective: In recent years it has become evident that tissue cyclooxygenase-2 (COX-2) may play a role in carcinogenesis and tumor malignancy. There is now a mounting body of information that strongly implies that COX-2 inhibitors may be of some value in the management of patients with carcinomas, and most recently several similar reports have appeared relating to sarcomas. Methods: The authors studied 32 samples of cartilage tumors from our tumor tissue bank for the presence of COX-2 by a Western blot technique. There were 29 patients from whom the samples were obtained, including 8 with enchondromas and 21 with chondrosarcomas. Results: Thirteen of the 24 chondrosarcoma samples and none of the 8 enchondromas were positive for COX-2. An attempt was made to correlate these results with clinical data including age, gender, staging according to the Musculoskeletal Tumor Society, anatomical site, ploidic pattern, presence of metastases and death rate but no statistically valid correlation could be found. Conclusion: It is evident that COX-2 may play some role in chondrosarcoma but not in the benign enchondroma and that further studies with COX-2 inhibitors are warranted.

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