Can a pathologist tell the difference between types of cancer cells just by looking at them?

Sometimes.: Usually, samples of a lesion are taken, and looked at under a microscope. But an experienced pathologist might have a good idea of what a lesion is just by looking at it. Leiomyomas, for example, have a very characteristic appearance. But samples for the microscope are always taken to be sure.

Absolutely: Many diagnoses are naked-eye with near-perfect accuracy. Interestingly, prostate cancer is only 2/3 accurate by naked-eye. But we always use the microscope, and if the first stain doesn't give an unambiguous answer, we resort to a battery of additional stains. Molecular diagnosis is supplemental. Pathology has been for me the fascination of a lifetime.

Looking at CA cells: That's the whole name of the game.Tissue is sent to the pathologist who "looks" at it under the microscope and then tells the rest of us what kind of cancer it is, if it is slow growing, and how it responded to a number of different stains.Pathologists are the heroes behind the scenes who basically determine a patient's fate.

Pathologist: Often times, yes! Surgical pathologists use microscopy to evaluate and classify tumors and other conditions. The majority of "common" cancers can be diagnosed by "just looking at them". However, some cancers are "undifferentiated" and need additional studies, like special staining with antibodies, or molecular studies, to determine exactly what kind of cancer it is.