Tumor Consistency as a Predictor of Successful Pseudocapsular Dissection of Pituitary Adenomas

Pseudocapsular dissection is a well described technique for the separation of pituitary tumors from the normal pituitary gland. It has been suggested that this surgical technique may allow for improved tumor identification and gross-total resection of these lesions. It is well known that smaller pituitary adenomas tend to have a higher proportion of intact pseudocapsules and therefore tend to have more successful extracapsular dissections. However, tumor consistency and firmness has not been evaluated as a predictor of successful pseudocapsular dissection. Therefore, we evaluated whether the intra-operative consistency of the tumor predicted the rate of successful pseudocapsular dissection. Exclusionary criteria included final pathology that was not consistent with pituitary adenoma, imaging or clinical evidence of apoplexy, prior endoscopic endonasal surgery, and cases in which pseudocapsular dissection was not planned or attempted. This resulted in a series of 475 consecutive pituitary adenomas. Tumors were classified as a “complete” pseudocapsular dissection if the tumor was removed en bloc with the capsule, or in the case of larger tumors if the tumor was initially centrally debulked then a complete pseudocapsular dissection was performed. All tumors in which this was attempted but could not be performed were classified as a failed pseudocapsular dissection attempts. At the same time, tumors were classified as “soft” if they could be removed with suction, “semi-firm” if they could be removed with curettes, and “firm” if sharp dissection was required. There was no significant difference in gender or age of either group. Both groups consisted of 57% nonfunctional adenomas and 43% functional (secreting) adenomas. Rate of intra-operative CSF leak was 31% in the failed pseudocapsular dissection group and 20% in the successful pseudocapsular dissection group. In the group with failed pseudocapsular dissections, 76% of tumors were soft, 17% were semi-firm, and 7% were firm. In the group with successful pseudocapsular dissections, 72% of tumors were soft, 22% were semi-firm, and 6% were firm. There was no statistical difference with respect to success of pseudocapsular dissection and tumor consistency. In this study, pituitary tumor consistency was not a statistically significant predictor of the success of pseudocapsular removal of tumor. Further studies are needed to determine what factors may play a role in the success of a extracapsular dissection of pituitary adenomas.