The "double-peak" pattern of pituitary adenoma intrasellar pressure and its impact on the microvascular structure

OBJECTIVE The purpose of this study was to investigate the relationship between intrasellar pressure (ISP) and the microvascular structure of pituitary adenomas. METHOD We retrospectively analysed ISP in 66 patients with pituitary adenomas. The corresponding microvascular structure was obtained using immunohistochemistry and analysed for its correlation with the ISP. RESULTS The average ISP was 25.89±8.27 mmHg, and the ISP was not related to the size of the adenoma (Pearson correlation coefficient=0.103, P=0.415). The ISPs of adenomas with different Knosp grades were significantly different (P<0.05). From grade 0 to grade 4, at first the ISP increased with Knosp grade and reached the first peak at grade 2, then it decreased at grade 3, and increased again at grade 4, showing a "double-peak" pattern. The minimal diameter and perimeter of microvessels and the percentage of vessel-covered area were positively related to ISP, and when these parameters were compared among adenomas of different Knosp grades, they also exhibited a "double-peak" pattern. CONCLUSION This study reported that with the increase in pituitary adenoma size and the invasion of surrounding tissues, the ISP of pituitary adenomas showed a "double-peak" pattern. The ISP and certain parameters of the microvascular structure are related, as the microvasculature adaptively changes its structure in response to the changing ISP to ensure sufficient blood supply to the adenoma. The specific mechanism of this phenomenon needs further study.