gms | German Medical Science

Objective: Knowledge about hormone receptor expression turned out to be essential for the management of pituitary adenomas, especially for prolactinoma and GH-secreting adenomas. For this reason we analyzed the expression of hormone receptors of 36 resected pituitary adenomas by immunohistochemistry.

Method: 124 patients with lesions around the sella underwent microsurgery during the last 4 years (non secreting adenomas 71, secreting 36, others 17). Immunohistochemistry was performed in 36 hormone secreting adenomas with antibodies against GH-, PRL-, TSH-, LH-, ACTH- and FSH-receptors, as well as Dopamine-receptor 1 (DRD 1) and 2 (DRD 2) and against the Somatostatinreceptor-subtypes SST 1, 2a, 3, 4, and 5. Moreover, the proliferative activity was determined with the Ki67 antibody. Clinical normalization after surgery was judged as follows- for GH-oma: IGF-1 normalized; GH <1 ng/ml after oral intake of 100 g glucose; for ACTH-oma: Cortisol and ACTH within normal range at 7 AM on 1. POD; for PRL-oma/TSH-oma: Serum-PRL/-TSH within normal range. If this was not achieved, an early reoperation was performed within one week.

Results: 36 patients suffered from secreting adenomas: acromegaly 23, Cushing 8, PRL-oma 4, TSH-oma 1. The overall normalization ratio after operation was 9/10. Ki67 >5% disclosed to be risky for recurrence. The extensively analyzed pattern of hormone receptors, including the Dopamine and Somatostatin subtypes showed no correlation to surgical risk, normalization ratio, nor risk of recurrence. SST 2a receptor was overexpressed in 22 out of 23 patients with GH-oma.

Conclusions: It is of special value to know the immunohistochemical expression pattern of SST-subtypes in GH producing pituitary adenomas when the hormone level of the patients cannot be normalized by microsurgery. For patients with an overexpression of SST-2a receptor, a target therapy with SST 2a antagonists can be considered as a novel and promising alternative to radiotherapy.