Metastasizing APUD cell tumours of the human gastrointestinal tract. Light microscopic and karyometric studies.

A total of 11 metastasizing gastrointestinal APUD cell tumours from biopsy and autopsy files were reclassified according to Soga and Tazawa as well as to WHO Histologic Classification of Tumours. The much higher proportion of APUD cell tumours in autopsies (11 cases from 1000 autopsies in comparison with 22 cases from 22 000 biopsies) demonstrate that the majority of them will not be discovered during the patient's life. EC cell carcinoids (type A) predominate in both non-metastasizing and metastasizing gastrointestinal APUD cell tumours. Metastases from EC cell carcinoids occurred only in regional lymph nodes and in the liver. The APUD cell tumours originating in the pancreas represent the most frequently metastasizing gastrointestinal carcinoids. Besides in the liver and in regional lymph nodes metastases from pancreatic APUD cell tumours were seen in the skin, the brain and the skeleton. One case with two (pancreatic, bronchial) competitive primary APUD cell tumours and a skin metastasis was studied by means of automated cell image analysis. Cell populations of these three tumour sites were characterized by morphometric and densitometric nuclear parameters. It could be demonstrated that the skin metastasis consisted of a cell population, which occurred as a subpopulation in the primary tumour of the bronchus. The results of karyometric investigations supported the hypothesis that single components of tumours can metastasis selectively.