Tumor volume improves preoperative differentiation of prolactinomas and nonfunctioning pituitary adenomas

Abstract

Purpose Both prolactinomas and nonfunctioning adenomas (NFAs) can present with hyperprolactinemia. Distinguishing them is critical because prolactinomas are effectively managed with dopamine agonists, whereas compressive NFAs are treated surgically. Current guidelines rely only on serum prolactin (PRL) levels, which are neither sensitive nor specific enough. Recent studies suggest that accounting for tumor volume may improve diagnosis. The objective of this study is to investigate the diagnostic utility of PRL, tumor volume, and imaging features in differentiating prolactinoma and NFA. Methods Adult patients with pathologically confirmed prolactinoma (n = 21) or NFA with hyperprolactinemia (n = 58) between 2013 and 2020 were retrospectively identified. Diagnostic performance of clinical and imaging variables was analyzed using receiver-operating characteristic curves to calculate area under the curve (AUC). Results Tumor volume and PRL positively correlated for prolactinoma (r = 0.4839, p = 0.0263) but not for NFA (r = 0.0421, p = 0.7536). PRL distinguished prolactinomas from NFAs with an AUC of 0.8892 (p < 0.0001) and optimal cut-off value of 62.45 ng/ml, yielding a sensitivity of 85.71% and specificity of 94.83%. The ratio of PRL to tumor volume had an AUC of 0.9647 (p < 0.0001) and optimal cut-off value of 21.62 (ng/ml)/cm3 with sensitivity of 100% and specificity of 82.76%. Binary logistic regression found that PRL was a significant positive predictor of prolactinoma diagnosis, whereas tumor volume, presence of CSI not previously defined, and T2 hyperintensity were significant negative predictors. The regression model had an AUC of 0.9915 (p < 0.0001). Conclusions Consideration of tumor volume improves differentiation between prolactinomas and NFAs, which in turn leads to effective management.

Serum Prolactin Level to Tumor Size Ratio as a Potential Parameter for Preoperative Differentiation of Prolactinomas from Non-Functional Pituitary Adenomas

“…21.62 [ng/mL] / as the cut off value with a sensitivity of 100% and speci city of 82.76%. However, the statistical difference in diagnostic performance between the ROCs of PRL/V and serum PRL level alone was not described [11]. Further investigation is needed due to the smallsized sample and heterogeneous pathologies in the control group.…”

“…Serum PRL levels > 500 µg/L are generally always indicative of prolactinomas [2,8]. Concerning lactotroph tumor cells secreting PRL, hyperprolactinemia of prolactinomas are known to be associated with tumor size [9][10][11]. While serum prolactin levels were usually at least 250 µg/L reaching 20,000 µg/L or more in macroprolactinoma, microprolactinomas with an MD less than 10 mm result in serum PRL levels of 100-200 µg/L [2,9].…”

Risk factors for delayed postoperative hyponatremia in patients with non-functioning pituitary adenomas undergoing transsphenoidal surgery: A single-institution study

“…The degree of hyponatremia was evaluated as follows: mild (130–134 mEq/L), moderate (125–129 mEq/L), and severe (<125 mEq/L) hyponatremia. Hyperprolactinemia is defined as a plasma prolactin level of >18 ng/ml in men or 25 ng/ml in women ( 10 ). The pituitary region was scanned with 3.0 T MRI before surgery.…”

“…Measurement of transverse, craniocaudal, and anteroposterior dimensions were recorded using T1-enhanced images. Tumor volume was calculated using the simplified ellipsoid volume equation ( 10 ). The angle at which the pituitary stalk deviates from the midline is measured in the coronal plane and called the pituitary stalk deviation angle ( 11 ) ( Figure 1 ).…”

Machine-Learning Prediction of Postoperative Pituitary Hormonal Outcomes in Nonfunctioning Pituitary Adenomas: A Multicenter Study

“…Therefore, the GH levels in GTR cases are higher than those in STR against surgical stress. Increased PRL in NFPAs frequently occurs because of inhibitory dopamine transportation from the hypophyseal portal system (21,22). GTR could effectively relieve the compression of the pituitary stalk than STR.…”