Beta-catenin is a crucial part of the Wnt and
E-cadherin signalling pathways, which are involved in
tumorigenesis. Dysregulation of these pathways allow
beta-catenin to accumulate and translocate to the nucleus, where it may activate oncogenes. Such nuclear accumulation can be detected by immunohistochemistry, which may be useful in diagnosis. Although the role of
beta-catenin has been established in various types of
carcinomas, relatively little is known about its status in mesenchymal
tumors. A number of studies suggest that
beta-catenin dysregulation is important in
desmoid-type
fibromatosis, as well as in
synovial sarcoma. We wished to determine whether nuclear
beta-catenin expression is specific to and sensitive for particular bone and soft-tissue
tumors, including sporadic
desmoid-type
fibromatosis. We studied the nuclear expression of
beta-catenin using tissue microarrays in a comprehensive range of bone and soft-tissue
tumor types. A total of 549 cases were included in our panel. Nuclear immunohistochemical staining was determined to be either high level (>25% of cells), low level (0-25%) or none. High-level nuclear
beta-catenin staining was seen in a very limited subset of
tumor types, including
desmoid-type
fibromatosis (71% of cases),
solitary fibrous tumor (40%),
endometrial stromal sarcoma (40%) and
synovial sarcoma (28%). Although occasional cases of
fibrosarcoma,
clear cell sarcoma and
carcinosarcoma had high-level staining, no high-level nuclear
beta-catenin expression was seen in any of 381 fibrohistocytic, muscular, adipocytic, chondroid or osseous
tumor cases representing 42 diagnostic categories. All primary immunostain tissue microarray images are made publicly accessible in a searchable database. High-level nuclear
beta-catenin staining serves as a useful diagnostic tool, as it is specific to a small subset of mesenchymal
tumors.