Prognostic relevance of intracytoplasmic cytokeratin pattern, hormone expression profile, and cell proliferation in pituitary adenomas of akromegalic patients.

ABSTRACT

Seventy-six pituitary adenomas of akromegalic patients were investigated to find out the prognostic relevance of the intracytoplasmic distribution of cytokeratins (CK), immunohistochemically defined hormone production profile, proliferative activity and clinical presentation. CK distribution, growth fraction (MIB1 index) and hormone production profile were analyzed by means of immunohistochemistry. Apoptotic activity was investigated by the TUNEL method. Two different CK distribution patterns were seen a dot-like pattern in 29 cases (type 1 adenomas), and a perinuclear fibrillary pattern in 47 cases (type 2 adenomas). Type 2 adenomas showed more prominent coexpression of prolactin (p < 0.0001), luteotrophic hormone (p < 0.002), follicle-stimulating hormone (p < 0.005), thyroid-stimulating hormone (p < 0.0001), and alpha-subunit (p < 0.005), as compared to type 1 adenomas. The mean MIB1 index was significantly higher in type 1 vs. type 2 tumors (4.23%, range 1.93% - 9.83% vs. 2.07%, range 0.67% - 4.87%, p < 0.0001). Apoptotic activity was too low in both examined groups to be used for balancing of tumor cell turnover. Clinical analysis of patients with type 1 adenomas revealed female predominance, younger age, larger tumor size, and more frequently aggressive growth with higher incidence of suprasellar extension (p < 0.0001) and cavernous sinus infiltration (p < 0.0001), as well as larger proportions of re-operations and incomplete resections (34.5% vs. 8.51%). Additionally, the interval until re-operation was shorter in type 1 adenomas (mean 16 months, range 9 - 21 months vs. mean 57 months, range 18- 158 months). We conclude that classification of adenomas of akromegalic patients based on intracytoplasmic CK distribution, combined with examination of proliferative activity, and immunohistochemically defined hormone production profile, provides important prognostic information for the management of akromegalic patients.