(1) Background: The aim of the current study is to evaluate the immunohistochemical expression of Ki-67, CD-56, Cyclin-D1 and E-Cadherin in the tissues samples of pituitary adenomas (PAs) and its association with PAs clinical manifestation tumor size, invasiveness and the risk of recurrence. (2) Materials and Methods: Ninety-four patients who underwent endoscope transsphenoidal excision of PAs were included in our study. The immunohistochemical expression of the Cyclin-D1, CD-56, E-Cadherin and Ki-67 markers was analyzed in paraffin-embedded tissue samples. (3) Results: The expression of Cyclin-D1 and Ki-67 index levels was positively correlated with the size (p < 0.001, r = 0.56 and p < 0.001, r = 0.43, respectively), the recurrence (p < 0.001, r = 0.46 and p = 0.007 r = 0.3, respectively), the extrasellar extension (p < 0.001, r = 0.48 and p < 0.001, r = 0.4, respectively) and the cavernous sinus invasion of (p < 0.001, r = 0.39 and p < 0.001, r = 0.3, respectively). No correlation was found between CD-56 and E-Cadherin expression with the size, the invasiveness and the recurrence of PAs. (4) Conclusion: Cyclin-D1 and Ki-67 are promising immunohistochemical markers in predicting the invasive behavior and recurrence of PAs in contrast to E-Cadherin and CD-56 which did not seem to be associated with PAs behavior post-surgery. However, larger studies are required in order to establish their role in the routine evaluation of PAs.
Keywords: Cyclin-D1; Ki-67; adenoma; markers; pituitary; prognostic.