Synchronous tumours detected during cancer patient staging: prevalence and patterns of occurrence in multidetector computed tomography

Purpose
The incidental detection of one or more additional primary tumours during computed tomography (CT) staging of a patient with known malignancy is rare but possible. This occurrence should be considered by the radiologist when a new lesion is detected, especially if the lesion location is atypical for metastases. The purpose of this report was to document the usefulness of total body CT scan to detect synchronous primary malignancies in cancer patients undergoing a staging workup.

Material and methods
This was done by reviewing the staging CT studies of the adult patients with a newly diagnosed cancer evaluated during a five-year period in a single cancer institute in order to identify any possible correlation, establishing which tumours are more frequently combined with a second tumour and which second tumours are more commonly present.

Results
Among the patients with a second tumour, the most frequent first primary tumours were melanoma (eight patients, 17.8%), lymphoma (seven patients, 15.6%), and prostate carcinoma (seven patients, 15.6%). The most frequent incidentally detected second tumours were hepatocellular carcinoma (nine patients, 20% of 45 incidental tumours), renal carcinoma (eight patients, 17.8%), lung carcinoma (seven patients, 15.6%), and bladder carcinoma (four patients, 8.9%). One patient had three primary tumours synchronously.

Conclusions
We believe that the radiologist’s knowledge of the prevalence and pattern of occurrence of these multiple primary malignancies represents added diagnostic value.