Relative Usefulness of Electron Microscopy and Immunocytochemistry in Tumour Diagnosis: 10 Years of Retrospective Analysis

Aims: To determine retrospectively the relative usefulness of electron microscopy and immunocytochemistry for tumour diagnosis; to monitor the influence of new antibodies and antisera on the use of these techniques in one laboratory.

Methods: During 1980 to 1989 inclusive, 726 tumours were examined by electron microscopy, 862 by immunocytochemistry, and 286 by both techniques. The choice of techniques and, for immunocytochemistry, the range of antibodies used were compared between each category of final diagnosis.

Results: During the study period there was a sharp fall in the use of electron microscopy and a corresponding rise in immunocytochemistry. These trends applied to all categories of final tumour diagnosis, but the use of electron microscopy was sustained longer for lesions suspected or eventually confirmed to be melanomas or amine precursor uptake decarboxylation cell carcinoma (APUDomas)--for example, carcinoid tumours. The immunocytochemistry:electron microscopy use ratios ranged from 2.07:1 to 0.44:1 for the categories in which lymphoma and APUDoma, respectively, were the final diagnoses. The abandonment of electron microscopy for suspected or confirmed lymphomas and carcinomas corresponded to the increasing availability of relevant antisera and antibodies.

Conclusions: The wider application of immunocytochemistry for tumour diagnosis is endorsed, but electron microscopy should be retained for selected cases in which the results of immunocytochemistry might be predictably ambiguous or otherwise unhelpful.