Pathologists are the most important doctors that patients never meet. Their expertise is essential to help diagnose disease, figure out how far it has spread, and determine the best treatment options. They huddle over microscopes much as they have for the last 100 years, peering at slivers of human tissue, cells and bodily fluids on glass slides to unlock the medical mysteries in cells. There can be significant differences in how pathologists interpret what they see under the microscope or with the naked eye, a growing number of studies show. That can lead to serious consequences for patients if pathologists miss cancer, or conversely, if they interpret a benign tumor as malignant. [Subscription Required]