Intra-Articular Synovial Sarcomas: Incidence and Differentiating Features from Localized Pigmented Villonodular Synovitis

Purpose. To determine the incidence of intra-articular synovial sarcomas and investigate if any radiological variables can differentiate them from localized (unifocal) pigmented villonodular synovitis (PVNS) and if multivariate data analysis could be used as a complementary clinical tool. Methods. Magnetic resonance images and radiographs of 7 cases of intra-articular synovial sarcomas and 14 cases of localized PVNS were blindedly reviewed. Variables analyzed were size, extra-articular growth, tumor border, blooming, calcification, contrast media enhancement, effusion, bowl of grapes sign, triple signal intensity sign, synovial low signal intensity, synovitis, age, and gender. Univariate and multivariate data analysis, the method of partial least squares-discriminant analysis (PLS-DA), were used. Register data on all synovial sarcomas were extracted for comparison. Results. The incidence of intra-articular synovial sarcomas was 3%. PLS-DA showed that age, effusion, size, and gender were the most important factors for discrimination between sarcomas and localized PVNS. No sarcomas were misclassified as PVNS with PLS-DA, while some PVNS were misclassified as sarcomas. Conclusions. The most important variables in differentiating intra-articular sarcomas from localized PVNS were age, effusion, size, and gender. Multivariate data analysis can be helpful as additive information to avoid a biopsy, if the tumor is classified as most likely being PVNS

Interferon-inhibited human osteosarcoma xenografts induce host bone in nude mice.

The growth of human osteosarcoma xenografts in nude mice can be inhibited by human interferon-alpha (IFN-alpha). Histologic examination of growth-inhibited tumors has revealed mineralization and partial replacement of the tumor by normal bone tissue. We have investigated whether the normal bone tissue was formed by differentiated tumor cells or by induction of host stroma to differentiate into bone tissue. Employing antibodies to both murine and human type I collagen, it was found that the normal bone produced in IFN-inhibited osteosarcomas was host derived. These results suggest that IFN induced the osteosarcoma cells to produce a bone-inductive agent that interacts with the host cells, and leads to the formation of mature normal bone tissue in a heterotopic site

Interferon-inhibited human osteosarcoma xenografts induce host bone in nude mice.

The growth of human osteosarcoma xenografts in nude mice can be inhibited by human interferon-alpha (IFN-alpha). Histologic examination of growth-inhibited tumors has revealed mineralization and partial replacement of the tumor by normal bone tissue. We have investigated whether the normal bone tissue was formed by differentiated tumor cells or by induction of host stroma to differentiate into bone tissue. Employing antibodies to both murine and human type I collagen, it was found that the normal bone produced in IFN-inhibited osteosarcomas was host derived. These results suggest that IFN induced the osteosarcoma cells to produce a bone-inductive agent that interacts with the host cells, and leads to the formation of mature normal bone tissue in a heterotopic site