The clinicopathological and DNA flow cytometric data of 33 patients with stromal tumours of the gastrointestinal tract (STGIT) were analysed to select pathological features of prognostic value. Tumours had been previously classified as benign (21 cases) or malignant (12 cases). Data relating to poor prognosis statistically were local invasion, pathological grade, size greater than 10 cm, mitotic index (MI) and necrosis. Pathological grade was related to local invasion. Aneuploidy did not correlate with poor survival although a common trend was detected between both. DNA content may help to predict prognosis of STGIT, but its real value has not yet been clearly established. Currently, stage (invasion), size, MI and pathological grade remain the most useful prognostic factors.

Flow cytometry was used for comparative in vivo and in vitro analysis of cell populations staining positively for somatostatin. Experiments were carried out with pineals obtained from neonatal, 8- and 15-day-old rats. Pineal cells were obtained by dispersion with collagenase and then processed in a flow cytometer or maintained in culture for 1 or 2 weeks. Identification of somatostatin-immunopositive cell populations was performed using a polyclonal somatostatin antibody and confirmed by indirect immunostaining of cytospun smears with the avidin-biotin-peroxidase method. In vivo, the percentage of somatostatin-positive cells was 60.6 ± 4% in neonatal pineals and declined to 22.2 ± 11 % in 15-day-old animals (p < 0.04). The density of peptide immunostaining decreased in 8-day-old animals but recovered to the neonate levels in 15 day-old animals; homogeneity in the immunopositive population increased with age. Maintenance in culture for 1 week resulted in an increase in positive somatostatin staining in animals of 8 and 15 days with no changes in neonates; however, after 2 weeks of culture, the percent of immunopositive cells decreased from 53.3 ± 6 to 12.2 ± 4% in the older animals and remained unchanged in neonates. We conclude that somatostatin is found in pinealocytes and shows a declining pattern during the perinatal period; this probably implies that the peptide plays a paracrine role important for cell differentiation in these young animals, since maximal cellularity and a high mitotic index occur within the first 3 days of life, and pineal cell differentiation is completed before the end of the third week of extrauterine life.

Using flow cytometry, DNA content and index, and/or proliferative capacity (measuring proliferating cell nuclear antigen PCNA) in operated pituitary tumors, control pituitaries obtained at necropsy, and experimental pituitary hyperplasia induced in rats were analyzed. Simultaneous measurement of cell ploidy and proliferation differentiated normal pituitary (diploid DNA index and negative PCNA) from pituitary hyperplasia (diploid DNA index with intensely positive PCNA, between 30 and 72% of cells). In the tumors 83% (19/ 23) were positive for PCNA (between 3 and 84%) and 73% (17/23) aneuploid; only 1 tumor was diploid and negative for PCNA. Conclusions: Differentiation between normal and abnormal (neoplastic or hyperplastic) pituitary is possible by flow cytometry, but in the adenomas no correlation with postoperative clinical outcome was observed.

No abstract