Yoji Kawaguchi

Intraarticular osteoid osteoma associated with synovitis : a possible role of cyclooxygenase-2 expression by osteoblasts in the nidus

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-1β 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.

Mechanism of intramedullary high intensity area on T2‐weighted magnetic resonance imaging in osteoid osteoma: A possible role of COX‐2 expression

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.

Expression of mRNAs encoding hormone receptors in the endolymphatic sac of the rat.

The endolymphatic sac (ES) is believed to absorb the endolymphatic fluid produced by the stria vascularis and vestibular dark cells. Recent studies have implied that the function of the ES may be controlled by circulating hormones, suggesting that hormone receptors should exist there. In the present study, the expression of genes encoding receptors for aldosterone, atrial natriuretic peptide (ANP) and vasopressin in the ES was examined by reverse transcription-polymerase chain reaction (RT-PCR). Next, the cellular localization of the expression of these genes was investigated by in situ hybridization. RT-PCR indicated that aldosterone. ANP-A and vasopressin V1a receptor genes were expressed in the ES. In contrast, neither ANP-B nor vasopressin V2 receptor gene expression was detected. In situ hybridization experiments demonstrated aldosterone receptor gene expression in epithelial cells of the intermediate potion of the ES, while expression of ANP-A or V1a receptor genes was not detected. The present results suggested that aldosterone may play a specific role in the function of the ES. However, we could not conclude that ANP and vasopressin play physiological roles in the ES because receptors for these hormones were detected only by highly sensitive PCR.

Ischiogluteal bursitis: a report of three cases with MR findings

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.

A comparative study of F-18 FDG PET and 201Tl scintigraphy for detection of primary malignant bone and soft-tissue tumors.

Purpose: The purpose of this study was to compare 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) and Tl-201 chloride (Tl) scintigraphy for detection of primary malignant bone and soft-tissue tumors. Materials and Methods: A total of 40 patients with suspicion of malignant bone and soft-tissue tumors were examined. FDG PET imaging was performed at 1-hour post-FDG injection. Tl planar and single photon emission computed tomography images were acquired 10 minutes (early) and 2 hours (delayed) after injection of Tl. We evaluated FDG and Tl uptake visually and semiquantitatively using standardized uptake value and tumor to contralateral normal tissue ratio on planar images, respectively. Results: Of the 33 patients with malignant tumors, all but 2 liposarcomas showed positive accumulation on FDG PET. However, all 7 benign lesions were also positive on FDG PET. Both early and delayed Tl images were positive for 27 of the 33 malignant tumors. Of the 6 false-negative cases on Tl images, 5 were liposarcomas. Both early and delayed Tl images were negative for 5 of the 7 benign lesions. The sensitivity of FDG PET for detection of primary malignant bone and soft-tissue tumors was 94% and the specificity, 0%. The corresponding values for Tl scintigraphy were 82% and 71%. The mean FDG standardized uptake value in malignant tumors was higher than that in benign lesions, but this difference was not statistically significant. Statistically significant differences were observed between malignant and benign lesions for both early and delayed tumor to contralateral normal tissue ratios. Conclusions: FDG PET was found to be more sensitive than Tl scintigraphy for primary malignant bone and soft-tissue tumors, although it was less specific.

Magnetic Resonance Imaging Findings of Microgeodic Disease of the Toe: A Case Report

Level of Evidence: V, Expert Opinion

A comparative study of2O1T1 scintigraphy and three-phase bone scintigraphy following therapy in patients with bone and soft-tissue tumors

Objective: The purpose of this study was to evaluate the usefulness of201T1 scintigraphy in comparison with three-phase bone scintigraphy in the differentiation of residual/recurrent tumors from post-therapeutic changes, in patients previously treated for bone and soft-tissue tumors.Methods: Thirty-five201T1 and three-phase bone scintigraphy scans were obtained for 30 patients with a history of bone or soft-tissue tumor who had undergone chemotherapy, radiation therapy, tumor resection, or a combination of these treatments. The planar201Tl images were acquired 10 mins (early) and 2 hrs (delayed) after the intravenous injection of 111 MBq201Tl-chloride. Three-phase bone scintigraphy was performed using 740 MBq99mTc-HMDP at the same lesion site as for201T1 imaging. The blood flow images were obtained every 10 sec for 2 mins and were immediately followed by the blood pool image after 5 mins. Three to 4 hrs later, bone images were obtained.201Tl and three-phase bone scintigraphies were correlated with the histopathologic findings and/or clinical follow-up of more than 3 months.Results: Of the 35 cases, 15 were free of disease and 20 had residual or recurrent tumors. Of the 20 residual or recurrent cases, all had true-positive201T1 early and delayed scans, while bone scintigraphy was true-positive on the blood flow, blood pool and bone images in 16, 18 and 12 cases, respectively.201T1 early and delayed images and99mTc-HMDP blood flow and blood pool images were false-positive in one patient. The histology of this false-positive case showed the presence of lymph proliferative tissue.Conclusions: Although201Tl uptake after treatment does not always indicate recurrence,201T1 scintigraphy may still be more useful than three-phase bone scintigraphy in the follow-up of patients with bone and soft-tissue tumors following therapy.