Comparison of immunological detection of 5-hydroxytryptamine by monoclonal antibodies with standard silver stains as an aid to diagnosing carcinoid tumours.

Immunoreactivity to a monoclonal antibody against 5-hydroxytryptamine (5HT) was compared with Churukian Schenk argyrophilia and Masson Fontana argentaffin staining as an aid to the diagnosis of 53 carcinoid tumours. Thirty four tumours were argentaffin positive, 50 were argyrophil positive, and 43 contained immunologically detectable 5HT. In general, argentaffin staining and immunological detection of 5HT failed to pick up tumours derived from the foregut of type B or type D morphology. Argentaffin negative tumours usually showed only focal immunoreactivity for 5HT. If immunological detection of 5HT is used alone as a marker for carcinoid tumours problems arise in the differentiation of carcinoid tumours from adenocarcinomas which may also contain 5HT. These results were compared with those culled from other reported techniques used as an aid to the diagnosis of carcinoid tumours.