Evaluation of suspected malignancies: Difference between revisions

Beyond determining overall malignancy diagnosis (such as adenocarcinoma), probable origin and staging, classification of tumors into a specific histopathologic type or grade is generally of relatively less value. In cases of clearly non-malignant tumors where it is difficult to determine the specific histopathologic type or grade, it is generally acceptable to conclude the evaluation and report it as such, unless the clinician specifically requests otherwise. For potentially malignant or high-risk tumors, typing and grading often still affects the management.

Ensure that any cancer undergoes reflex testing where applicable by local guidelines. When they are not applicable, a rule of thumb is to order individual DNA testing for up to 2 genetic targets, and to order genomic sequencing if there are more targets.

When samples need to be sent to an outside laboratory, follow their requirements and guidelines for each test. Generally, choose the tissue block with the greatest amount/area of the highest grade malignancy. For molecular proliferation tests (other than [[immunohistochemistry]]) such as Ki67, avoid samples with previous biopsy site or inflammation (as these will cause a false high proliferation rates). On the other hand, for next-generation sequencing, hemorrhage, necrosis and adipose tissue does not need to be minimized, as these contain only little genetic material.