To clarify the condition of development of synovitis associated with intraarticular osteoid osteoma (OO), expressions of cyclooxygenase-2 (COX-2) protein and its messenger ribonucleic acid were investigated both in the nidus and the synovial tissue using immunohistochemical and reverse transcription-polymerase chain reaction analyses. Diffuse and strong COX-2 immunoreactivity was found in osteoblast-like tumor cells in the nidus of all six cases of OO (three of six cases were intraarticular OO associated with synovitis) and one case of osteoblastoma associated with synovitis. Expression of COX-2 messenger ribonucleic acid was demonstrated in one case of OO associated with synovitis, and was higher in the nidus than that in the inflamed synovial tissue. However, there were no significant difference between the nidus and synovium in the expression of cytosolic phospholipase A2, one of the enzymes involved in arachidonic acid metabolism, and inflammatory cytokines such as interleukin-1␤ and tumor necrosis factor alpha. Finally, as there was only one case in which the examinations of gene expression were performed, no definitive overall conclusions could be reached; rather it is suggested that COX-2 expressed primarily by osteoblasts in the nidus of intraarticular OO may play a role in activating the pathway of arachidonic acid metabolism, resulting in synovitis of the involved joint.

✓Tumoral calcinosis commonly occurs in the articular soft tissues of the extremities but rarely in the spine. The authors performed surgery to treat lumbar tumoral calcinosis in a patient with scleroderma, in whom symptoms of neurological dysfunction had manifested. This 49-year-old woman presented with low-back pain and gait disturbance. Seven years before presentation, scleroderma had been diagnosed, and the patient had received medical treatment ever since. Imaging revealed tumoral calcinosis centered at the bilateral facet joints between L-3 and L-4, marked stenosis of the spinal canal, L-3 spondylolisthesis, and intervertebral instability. Surgery was performed to excise the lesion en bloc. After neural decompression, posterolateral fusion and pedicle screw fixation were undertaken. Symptoms improved after surgery. In this case, the underlying scleroderma that predisposes to calcinosis and facet joint degeneration due to lumbar spondylolisthesis were probably factors leading to the development of tumoral calcinosis in the lumbar spine.

No abstract

To study the mechanism and pathophysiology of the development of intramedullary high intensity areas on T2-weighted magnetic resonance images (MRI) in cases of osteoid osteoma, we examined the expression of cyclooxygenase-2 (COX-2) in the nidus and surrounding bone tissues. In all six cases showing a marked intramedullary high intensity area adjacent to the nidus before surgery, neoplastic osteoblasts inside the nidus showed strong and diffuse COX-2 immunoreactivity. On the other hand, the osteoblasts rimming the surrounding reactive bone were COX-2 negative. In two cases examined by reverse transcription-polymerase chain reaction (RT-PCR), COX-2 mRNA was detected in abundance in the nidus. Histologically, vascular dilatation together with intramedullary edema was observed in all cases, which was probably reflected as a high intensity area on T2-weighted MRI. From our study, a high level of COX-2 expression in neoplastic osteoblasts in the nidus of osteoid osteomas may cause the secondary changes depicted by MRI.

Ischiogluteal bursitis is an uncommon disorder which can be confused with neoplastic conditions in the buttock. Three cases of ischiogluteal bursitis in a 57-year-old man, a 73-year-old woman and a 73-year-old man are presented. All patients presented with a gradually increasing, painful buttock mass. Magnetic resonance imaging (MRI) revealed a soft tissue mass around the ischial tuberosity and showed various features in the three cases. Two patients underwent excision of the lesion, which was histologically diagnosed as ischiogluteal bursitis. One patient was conservatively treated and the symptoms gradually decreased. MRI was very useful in diagnosing and detecting the lesion. Ischiogluteal bursitis should be considered in the differential diagnosis of a buttock mass.