The incidence of micrometastases in cervical lymph nodes from squamous cell carcinomas of the head and neck was studied using routine histopathological examination. Micrometastases were found in 66 lymph nodes in 41 of the 92 tumor-positive neck dissection specimens. The detection of these micrometastases influenced postoperative treatment in 3 of the 77 patients with neck node metastases. The value of additional sectioning for detecting micrometastases was thus assessed. Sectioning at a deeper level in 600 originally histopathologically negative lymph nodes from 64 patients revealed 7 additional micrometastases in 5 patients. Antikeratin staining with a mixture of two monoclonal antibodies (AE1 and AE3) revealed 4 micrometastases in 739 originally histopathologically negative lymph nodes in 3 of 13 patients studied. Because of the unknown prognostic significance of micrometastases and the consequent arbitrary consequences for postoperative treatment, present findings show that the extra workload of immunostaining and deeper sectioning does not warrant their routine use in clinical practise.

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SummaryA two-site immunoradiometric assay for factor VIII-procoagulant antigen (VIIICAg) that relies completely on monoclonal antibodies has been developed. By selecting an appropriate combination of these antibodies, it was possible to develop an assay in which the radiolabelled monoclonal antibody did not inhibit the binding of antigen to the solid-phase monoclonal antibodies. Thus, the entire test could be carried out as a one-step procedure. With this one-step assay, an amount of 0.0025 U VIIICAg/ml plasma could be detected after 4 hr of incubation, whereas 18 hr of incubation resulted in a lower limit of sensitivity of 0.0005 U VIIICAg/ml. The use of a one-step assay provides a significant advantage over the conventional two-step assay by simplifying, shortening and rendering the performance of the assay more convenient.

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