I would like to comment on the article by Lowe et al1 addressing the subject of evaluating micrometastases in sentinel lymph node biopsies (SLNBs) from patients with thin melanoma, because the discussion thus far neglects aspects of probability theory and statistics.
A micrometastasis is very small with respect to the size of even a small lymph node. In a morphometric study conducted 15 years ago, investigating at least 100 specimens per lymph node, we found micrometastases to represent between 0.0015% and 0.044% of the total lymph node volume (results presented at the Seventh International Dermatopathology Colloquium, May 23-25, 1986, Graz, Austria).
Bahmer FA. Sentinel Lymph Node Biopsy: The Issue of Probability and Statistics. Arch Dermatol. 2004;140(2):237. doi:10.1001/archderm.140.2.237-a