Staining collagen fibers in pituitary lesions substantially improves the certainty of intraoperative frozen section diagnosis

Abstract Purpose Transsphenoidal surgery is the first-line treatment for most pituitary adenomas (PA), also known as pituitary neuroendocrine tumors (PitNET), and a precise intraoperative histopathological evaluation of tissue samples is essential to optimize tumor resection and clinical outcome. However, it still remains a challenge for pathologists to distinguish between PA and pituitary gland. In this study, we evaluated the effect of an additional Cason collagen fiber stain on the accuracy of intraoperative histopathological diagnostics of PAs by visualizing either physiologically retained or pathologically lost lobulation. Methods A total of 252 cases were included in this study. In the control group ( n = 93) cytological smear preparations and H&E-stained frozen sections were evaluated. In the experimental group ( n = 159), both H&E- and Cason-stained frozen sections as well as smear preparations were examined. The concordance rate of the intraoperative diagnoses with the final diagnoses made on the paraffin material was determined. Results When compared with the HE only group, the HE+Cason approach markedly increased the diagnostic accuracy from 87% to 98% ( p < 0.001), sensitivity from 90% to 98% ( p < 0.05) and specificity from 40% to 100% ( p = 0.06), whereas the rate of inconclusive cases was significantly reduced from 11% to 0% ( p < 0.001). Conclusion This study introduces the Cason stain on frozen sections as a rapid, simple and inexpensive diagnostic tool essentially improving certainty in intraoperative histopathological diagnostics of PAs, thus facilitating surgical decision-making and optimizing clinical outcomes.