Methodological aspects of DNA image cytometry in formalin-fixed paraffin-embedded material from pancreatic adenocarcinoma.

Deparaffinized and disintegrated material from conventionally formalin-fixed and paraffin-embedded surgical specimens of 100 cases of ductal adenocarcinoma of the pancreas was Feulgen-stained, and the cytochemical DNA distribution patterns of at least 100 single tumour cells and 50 "control" cells (fibrocytes) were assessed by means of image cytometry (ICM). In 77 cases a sufficient number of neoplastic cells could be obtained for these DNA assessments. The fairly high number (23) of cases that had to be excluded due to too small amounts of disintegrated cells or cell nuclei may be explained by the high content of connective tissue stroma in these pancreatic adenocarcinomas. The tumour cell nuclei in 76 of these 77 cases showed cytochemically a clear-cut "non-diploid" DNA distribution pattern. This observation reflects the well-known highly malignant growth potential of this carcinoma. Despite the fact that about 1/4 of the tumours had to be excluded, the main result of our methodological study is, after all that conventionally formalin-fixed paraffin-embedded specimens of most pancreatic adenocarcinomas can be successfully used for the deparaffinization-disintegration procedure preceding the nuclear DNA assessments by means of ICM. Additional studies are, however, required to obtain the diagnostic and prognostic impact of the results of such cytochemical analyses of the DNA distribution pattern in adenocarcinomas of the pancreas.