[disclaimer] This degree of effort on all node dissections is controversial nationally & internationally, and none of the techniques are FDA approved or rejected. We determined in about 1980 that use of an inexpensive special fixative would aid in both the visual and palpable detection of lymph nodes even as small as 1-2 mm. in diameter. Hartmann's fixative is an alcoholic formalin solution which also contains acetic acid. It is a rapidly penetrating fixative which keeps fat soft and firms up almost all other tissues. By palpation, one can more readily feel the rounded to oval lymph nodes which fix distinctly firmer. The solution turns DNA-rich foci (nodes) white on cut surface, nodes often containing excessive amounts of DNA-rich lymphocytes.

PAs have given us a huge advantage! As our pathology group enlarged, it became apparent that optimal performance of a lymph node dissection appealed far more strongly to the pride-of-performance of a really good PA (pathologist assistant) than to the average pathologist. It is a thing of high importance to a properly motivated PA, while it is drudgery at the end of a mentally intense day for the average pathologist. Our PAs do node dissections on most of the breast, melanoma, and colon cancer cases. And, IHC has been a huge help in detecting positive nodes, especially in cancers such is invasive lobular breast cancer...which tends to invade nodes as single cells.

Does the throughness of histological sectioning of recovered nodes make any difference? When I began practicing in 1975, little or no effort was made to recover small nodes (maybe less than 0.5cm). And large nodes were typically sampled (maybe a representative block for a 1-2cm node). I remember numerous "poster presentations" at national meetings assuring us that small mets weren't of any definite prognostic consequence. But, in intervening years, oncologic treatment decisions have become much more complex. But, as of May 2001, all outcomes data was based on "ordinary processing". So, in about June 2002, reports began to come out which seemed to explain why 25% of node negative breast cancers behaved like node positive: stepcut sectioning through archived node blocks (from many years prior) converted about 25% of node negative cases to node positive...the mets were in the parafin blocks, undetected.

Does the number of nodes...the thoroughness of node dissection make any difference? Feb. 2002 issue of American Journal of Surgical Pathology reports a massive study proving that a maximal intensity of effort to recover all nodes actually resected from the colorectal cancer (CRC) patient is of high prognostic value ( 26:179-189, 2002)...to include 1 and 2 mm nodes! We have an even more intense protocol using agar depth sticks for node dissections in breast cancer, melanoma, and Merkel cell cancer cases (an intensity not needed in CRC).

Does the size & location of mets in a node make any difference? The finding of malignant cells in nodes means that the node is not negative. If it has a pattern of parenchymal invasion in the node, it is highly unlikely to be a cancer-cell-cluster caught in "mechaninical transport". And, if it is found in the efferent (exiting) aspect of the node, there is high risk that the next node in the cahin is positive, too.

Does the character of the malignancy increase the probability of positive nodes at time of diagnosis? Yes! Invasive micropapillary adenocarcinomas have an incredible tendency toward early node metastasis. Thick and/or high-mitotic-rate melanomas are more likely to have metastasized at the time of diagnosis. In colorectal cancer, as to H&E features, conspicuous Crohn's-like lymphoid reaction at the invasive front, lymphatic invasion, and conspicuous neutrophile infiltration of the malignant infiltration at the invasive front herald a likelihood that one should find one or more positive nodes¹ (remember to look fo tiny nodes that are immediately extramuscular). Here is our intense protocol for some cancers.

As an example of how well this has worked in our practice, I began the below file of examples 9/2001. It will contain some cases from the past and may be added to over time (but not by any means a complete tabulation!). Note the frequency of findings of one small positive lymph node. I promise you that no one should assume that our intensity of service and full-court press is duplicated in all pathology labs! In fact, when we first began, we were teased by other groups for being so compulsive (intense lymph node protocol used on breast & melanoma cases).

References:

1. Akishima-Fukasawa Y, et. al., Histopathological predictors of regional lymph node metastasis at the invasive front in early colorectal cancer, Histopathology 59(3):470-481, September, 2011.

(posted Sept. 2001, latest update 19 February 2012)