Endocrine Abstracts

Introduction: Pituitary neuroendocrine tumors (PitNET) are characterized by a heterogenous behavior. The immunohistochemical (IHC) staining of anterior pituitary hormones, along with that of pituitary transcription factors and with the clinical and biochemical characteristics of the patients can be integrated in a risk stratification system, which helps the therapeutic management.

Material and Methods: We analyzed 37 patients with confirmed diagnosis of acromegaly and 5 patients diagnosed with prolactinoma who underwent transsphenoidal pituitary surgery. The patient information was collected retrospectively. Using the postoperative tumour blocks, we performed morphological and IHC (anterior pituitary hormones: GH, PRL, TSH, FSH, LH, ACTH) analysis. Clinical data were extracted from medical charts. We correlated the IHC features of GH and PRL-secreting PAs with their clinical, laboratory and imaging data.

Results: Macroadenomas represented 88 % (37 cases) and the maximum mean diameter at diagnosis was 23,10 mm (the majority had Knosp grade II – 57%). Based on the morphological analysis (Hematoxylin and eosin method), histologically, the majority of tumors had diffuse growth pattern (80,95%). The intensity scores for anterior pituitary hormones were from 0 to 3+ (from absent to strong staining). We characterized the tumors according to the 2022 WHO classification. Immunohistochemistry showed 10 mixed mammosomatotroph PAs (GH/PRL) and 27 gonadotroph PAs. All of them showed intensive reaction for GH (3+). After surgery, only 2 patients were cured, 4 were in remission, 18 had controlled disease under medical treatment with somatostatin analogues and 10 under treatment with pegvisomant. Mean preoperative GH levels were 11.22 ng/ml (range: 0.97-44.7), and mean postoperative GH 4.82 ng/ml (range:0.09-30.5). Almost all patients diagnosed with prolactinomas (3 males and 1 female) had giant adenomas (maximum median tumour diameter was 43,6 mm), and after transsphenoidal surgery one patient was in clinical remission, 3 of them had controlled disease under treatment with dopaminergic agonists and one had uncontrolled disease under maximal doses.

Conclusions: The histopathological variability of pituitary adenomas (PAs) that cause growth hormone (GH) or prolactin (PRL) excess influences the clinical behavior, radiological characteristics and therapy response. The IHC classification and the radiological dimensions and extent influence disease control, and they are probably the best prognosis factors.

References: Asa SL, Mete O, Perry A, Osamura RY. Overview of the 2022 WHO Classification of Pituitary Tumors. Endocr Pathol. 2022 Mar;33(1):6-26. doi: 10.1007/s12022-022-09703-7. Epub 2022 Mar 15. PMID: 35291028.