Evaluation of sensitivity and specificity of doublecortin immunostatining for the detection of infiltrating glioma cells.

Diffuse gliomas are highly infiltrative intracranial tumors, but there are few useful markers for detecting infiltrating glioma cells in the surrounding brain tissue. Doublecortin (DCX) is a microtubule-associated protein (MAP) that plays a crucial role in neuroblast migration. It was recently demonstrated that DCX is preferentially expressed in invasive gliomas. However, the sensitivity and specificity of DCX as a marker for infiltrating glioma cells have not been fully evaluated. We immunohistochemically analyzed the expression pattern of DCX in human gliomas and compared it with that of MAP-2e, another marker for infiltrating glioma cells. We found that DCX was expressed specifically in infiltrating gliomas, but not in reactive, existing glia. Not all our cases exhibited stronger immunoreactivity to DCX at the invasive margin than at the core mass. The level of DCX expression was more variable from case to case than that of MAP-2e. For the identification of infiltrating glioma cells, DCX was thus more specific than MAP-2e whereas MAP-2e was more sensitive than DCX. DCX immunostaining would detect infiltrating low-grade glioma cells that are not efficiently labeled by proliferative markers. Taken together, DCX is applicable for the detection of individual infiltrating glioma cells when combined with other markers.