Main vascular changes seen in the saline controls of continuous infusion studies in the cynomolgus monkey over an eight-year period.

The aim of this study was to characterize the main vascular lesions seen in the saline controls in continuous infusion studies in monkeys. Data were collected from 17 studies over an 8-year period (ie, around 50 males and 50 females). The study was restricted to lesions at the injection site, in lungs and at the entry point. It showed that the level of the most severe procedure-related lesions (ie, necrosis with abscess formation at the injection site and at the entry point, thromboemboli and probable infarcts in lungs) was low (<10%). Minor changes such as endothelial hyperplasia and intimal thickening at the injection site, and low-graded interstitial pneumonitis in lungs were the most frequent changes (40 to 50% of the animals). Thrombi at the injection site were present in around 30% in males and 40% in females. The slightly higher incidence of thrombi in females was not explained by a difference of vessel size or by hematological differences. This study permitted an opportunity to harmonise terminology among pathologists and to define the main procedure-related changes and their incidence, which could help pathologists better interpret changes in future infusion studies.