CD34 IMMUNOEXPRESSION IN STROMAL TUMORS OF THE GASTROINTESTINAL-TRACTAND IN MESENTERIC FIBROMATOSES

The aim of this study was to explore whether CD34 immunoreactivity can distinguish between different types of gastrointestinal stromal, tumo ur, i.e. smooth muscle and neurogenic. We studied 87 stromal tumours f rom different sites in the gastrointestinal tract, as well as the omen tum and mesentery, using a monoclonal antibody to CD34 (QBEND10). We a lso determined the immunoexpression of smooth muscle and muscle specif ic actins, S-100 protein, cytokeratin, desmin and vimentin. In additio n, 15 cases of mesenteric fibromatosis were tested for CD34. Immunoexp ression of CD34 was observed in 40 of the 87 stromal tumours and corre lated with evidence of differentiation towards a smooth muscle phenoty pe. Large intestinal stromal tumours were less likely than gastric les ions to be CD34 positive. None of 15 cases of mesenteric fibromatosis was positive for CD34. We conclude that CD34 immunoexpression is seen in a proportion of stromal tumors of the gastrointestinal tract, mesen tery and omentum, particularly those of smooth muscle type, and it may be useful as part of an immunohistochemical panel in the differential diagnosis of these neoplasms.