Computed tomography in the evaluation of metastatic adenocarcinoma from an unknown primary site. A retrospective study.

Abdominal computed tomography (CT) and other studies were evaluated retrospectively in 46 patients with metastatic adenocarcinoma or undifferentiated carcinoma in whom the primary tumor site was not evident from the history, physical examination, or chest radiograph. The primary site was ultimately located in 21 patients (45.7%). CT of the abdomen in particular detected it in 16 patients (34.8%) and demonstrated additional and often unsuspected metastatic disease in 65%. CT proved superior to sonography in both diagnosis and assessment of the extent of disease and had a significantly higher diagnostic yield than contrast studies of the urinary and gastrointestinal tracts. abdominal CT is recommended as the initial modality in patients with metastatic adenocarcinoma of unknown primary origin. If the abdominal scan is negative, it should be followed by pelvic sonography or CT, particularly in women. Contrast studies should be limited to patients with specific organic dysfunction.