Microatheromas of very small arteries: unusual lesions involving primarily the pancreas.

The chance finding of an unusual, eccentrically situated, ballooning, atheroma-like acellular deposit of lipid and calcium in the wall of a very small pancreatic interlobular artery prompted a detailed review of 75 autopsies to determine the distribution, prevalence, and possible clinical significance of such lesions. The lesion was present in 12 of the 75 cases (16 per cent), and in ten it was limited to the pancreas. It correlated best with severe coronary atherosclerosis. In a significantly greater percentage of the cases in which it was present, either hypertension or diabetes, or both, were present. The incidence of pancreatic parenchymal disease was similar in both the positive and the negative groups. The lesion, which has apparently not been previously described, may be a peripheral extension of severe atherosclerosis of the large and medium-sized arteries. The morphologic features suggest that the altered vessel walls may be rupture-prone. Future studies of better-preserved portions of pancreas in cases of acute hemorrhagic pancreatitis may reveal the lesion and lend support to this hypothesis.