Gallium-67-citrate scintiscanning in the search for occult primary malignant tumours.

Fifty consecutive patients in whom occult primary malignant disease was suspected underwent scintiscanning of the head, neck and trunk with gallium-67-citrate. In 17 patients a carcinoma was correctly identified as to presence and approximate location. In another seven patients the site of the primary tumour was identified from the scan and confirmed by radiologic study but no histopathological diagnosis, except for metastatic anaplastic carcinoma, was made. In another five patients the many abnormalities on the scan did not permit identification of a possible site of the primary tumour. Eleven patients had normal scintiscans and no evidence of malignant disease on follow-up. In seven patients with proven carcinoma false-negative results were obtained: no uptake of the radioisotope was detected, even at the sites of known disease. In three patients false-positive uptake of the radiotracer was observed; two had benign disease and one had a malignant tumour remote from the scan abnormality.