Neoplasms of unknown primary site: a clinicopathological study of autopsied patients

Malignant neoplasms of an unknown primary site (NUPS) remain a diagnostic and therapeutic challenge in clinical practice. With this in mind, we have reviewed all autopsies performed in patients with NUPS in a single institution.

By reviewing 1656 autopsies performed on adults in our institution (1974-1990), 43 cases of NUPS were found. (NUPS was defined as histologically proven malignant tumor for which a primary site could not be found after anamnesis, complete physical examination, chest X-ray and routine chemistries.)

There were 24 men (56%) and 19 women. Mean age was 62 years (76% of patients were aged 40-75). Clinical presentation included general deterioration (73%), digestive symptoms (58%), liver enlargement (58%) abdominal pain (56%), respiratory symptoms (45%), ascites (26%) and node enlargement (16%). Abnormalities in analysis and image tests were frequent but nonspecific. Median time from admission to death was 42 days (range, 4-135). Pathologic diagnoses at autopsy were: 23 adenocarcinomas (53%), arising from pancreas (6), biliary tree (6), lung (3), prostate (2), stomach (1), kidney (1) and unknown (4); 3 squamous carcinomas (5%) (1 renal pelvis, 1 biliary tree, 1 stomach); 5 undifferentiated carcinomas (1 lung, 4 unknown); and 12 miscellaneous tumors (including 3 lymphomas, 3 neuroendocrine tumors, 3 hepatocarcinomas, 2 mesotheliomas and 1 melanoma). There was a tendency towards a metastatic pattern different from that expected from the primary tumor. Image tests were of little usefulness in the search for the primary tumor.

1) Adenocarcinomas were the most frequent tumor presenting as NUPS, especially from the pancreas and biliary tree. 2) In this series, at least 11% of patients were amenable to standard systemic therapies (3 lymphomas and 2 prostatic adenocarcinomas) if a correct pathologic diagnosis could have been established when alive. 3) Presenting symptoms and metastatic pattern differed from those expected for the primary neoplasm eventually found. 4) Image tests were often misleading as regards the primary site, although they were useful to quantify the dissemination of the tumor.