What is tissue diagnosis?

Pathology: A "mass" can be anything including non-cancer. A piece of tissue from a mass (or bone marrow biopsy, or blood) placed on a glass slide for a pathologist to review with special stains and sometimes molecular tests can give a "tissue diagnosis". With very few exceptions (eg, hcc, germ cell cancer) oncologists require a "tissue diagnosis" before treating cancer.

Tissue diagnosis: Tissue diagnosis is the diagnosis rendered by a pathologist and is based upon the microscopic examination of a tissue specimen removed during a biopsy/surgical procedure.