Metastatic spread to lymph nodes carries pro-found treatment and prognostic implications for patients with carcinomas, melanomas, or any other malignant neoplasm with metastatic po-tential. Accordingly, assessment of lymph node specimens is every bit as important as evaluating a neoplasm at its primary site.
Lymph Node Dissections
A general approach to sampling lymph nodes is described earily, and the organ-specific approach to the dissection of regional lymph nodes is detailed in each organ-specific.
Lymph nodes are easiest to appreciate in the fresh state before subtle distinctions in tissue den-sity are obscured by tissue fixation. Submersion of specimens in certain clearing agents may be help-ful in eliminating the bulk of adipose tissue, but this is an unnecessary and time-consuming step that does not improve on meticulous exam-ination of the fresh tissues. When appropriate, the anatomic levels of the lymph nodes should be maintained and separately reported in the sur-gical pathology report (e.g., colectomy speci-mens and neck dissection specimens). In cases where important anatomic landmarks do not accompany the specimen, it may not be possible to identify levels without the help of the sub-mitting surgeon.
Although tedious, the objective of any lymph node dissection for metastatic disease is nothing less than detection and processing of every lymph node contained in the specimen. There is practically no role for representative nodal sam-pling when searching for metastatic spread. Each lymph node identified should be submitted for microscopic examination. If tumor is grossly vis-ible, a section that includes the tumor suffices. If tumor is not grossly visible, the lymph node should be sectioned in 3- to 4-mm slices and all of the sections submitted for microscopic eval-uation. You can slice the lymph node along its long or short axis, but longitudinal sections are generally preferable, as this minimizes the number of slices. No single cassette should contain slices from more than one lymph node unless colored inks are used to distinguish different lymph nodes. For these nonsentinel lymph node dissections, one hematoxylin and eosin (H&E)-stained section per tissue block is adequate.