To investigate the correlation between postoperative pathological immunohistochemical classification of pituitary adenomas (PAs) and preoperative serum hormone levels.

Patients with PAs who underwent surgical treatment in Neurosurgery Department of General Hospital of Ningxia Medical University from July 2015 to November 2020 were selected as the study subjects. According to the preoperative pathological immunohistochemical staining classification guidelines, PAs were classified into adrenocorticotropic hormone (ACTH) tumors, prolactin (PRL) tumors, gonadotropin (GnH) tumors [luteinizing hormone (LH) tumors and follicle stimulating hormone (FSH) tumors], growth hormone (GH) tumors, thyroid stimulating hormone (TSH) tumors, and zero cell adenomas. General patient data, preoperative serum hormone levels, preoperative imaging reports, and postoperative pathological immunohistochemical staining results were collected. Spearman correlation analysis was used to assess the relationship between preoperative hormone levels and continuous variables such as age, gender, and tumor size. The Kappa consistency test was used to evaluate the diagnostic agreement between preoperative hormone levels and postoperative immunohistochemical classification.

Among the 213 patients with PAs, the 40-60 years age group had the highest number of cases (P<0.05); The proportion of macroadenomas was significantly higher than that of microadenomas and giant adenomas (P<0.05). In GH-secreting adenomas, preoperative GH levels showed a moderate negative correlation with age (r=-0.703, P<0.05). In multihormonal adenomas, preoperative PRL levels were correlated with gender (r=0.400, P<0.05), preoperative FSH levels were correlated with age (r=0.427, P<0.05), and there is no correlation between preoperative hormone levels and tumor size (P>0.05). Among different preoperative serum PRL level stratifications, using PRL>100 ng/mL as the diagnostic reference index yielded the highest agreement rate and Kappa coefficient (94.05%, 0.589). However, the consistency between postoperative pathological immunohistochemical staining diagnosis and preoperative hormone levels was poor in multi hormone adenomas, zero cell adenomas, ACTH tumors, GH tumors, TSH tumors, and GnH tumors.

The correlation between preoperative serum hormone levels and postoperative immunohistochemical classification has significant tumor type specificity. The clinical serological diagnosis of PRL-secreting adenomas was consistent with pathological immunohistochemical diagnosis, and PRL>100 ng/mL could serve as a serological reference value for diagnosing PRL-secreting adenomas. However, the postoperative pathological immunohistochemical staining diagnosis is inconsistent with preoperative hormone levels in multi hormone adenomas, zero cell adenomas, ACTH tumors, GH tumors, TSH tumors, and GnH tumors.