Patho-anatomical demonstration of lymph node metastases in a surgical specimen.

The prognosis of malignant disease is mainly determined by the demonstration or exclusion of lymph node metastases. However, other findings must also be considered, e.g., the number of lymph nodes examined and involved by tumor, differentiation between micro- and macrometastases, intranodal and perinodal growth, and non-neoplastic changes. These findings cannot be established with certainty when conventional examination methods (lamination and palpation) are used. Satisfactory results can only be obtained by employing a clearing technique and by processing the lymph nodes in step sections. For the speedy clearing of adipose tissue two devices have been developed in which hot acetone and xylene act on the tissue. In the transparent adipose tissue the lymph nodes can be easily recognized and accurately correlated topographically. In comparison to the routine method, the number of lymph nodes and nodal metastases detected can be doubled or tripled with this technique and with step sections. In particular, lymph nodes less than 5 mm in size and micrometastases (less than 2 mm) are visualized.