Giant Non-Functioning Pituitary Adenoma: Clinical Characteristics and Therapeutic Outcomes

Background Giant pituitary adenoma (>= 4 cm) is a rare tumor whose clinical features and prognosis are not well known. Aim To evaluate the clinical characteristics and therapeutic outcomes of giant non-functioning PA (gNFPA). Patients and Methods A retrospective multicenter study of gNFPA patients diagnosed in a 12-year period was performed. In each patient, clinical data and therapeutic outcomes were registered. Results Forty patients (24 men, age 54.2 16.2 years) were studied. The maximum tumor diameter [median (interquartile range)] was 4.6cm (4.1-5.1). Women had larger tumors [4.8cm (4.2-5.4) vs. 4.5cm (4.0-4.9); p=0.048]. Hypopituitarism [partial (n=22, 55%) or complete (n=9, 22.5%)] at diagnosis was present in 77.5% of the patients. Visual field defects were found in 90.9%. The most used surgical technique was endoscopic endonasal transsphenoidal (EET) surgery (n=31, 77.5%). Radiotherapy was used in 11 (27.5%) patients (median dose 50.4 Gy, range 50-54). Thirty-seven patients were followed for 36 months (10-67 months). Although more than half of these patients showed tumor persistence (n=25, 67.6%), tumor size was significantly reduced [0.8cm (0-2.5); p<0.001]. At last visit, 12 patients (32.4%) showed absence of tumor on MRI. Hypopituitarism rate was similar (75.0%), although with significant changes (p<0.001) in the distribution of the type of hypopituitarism. The absence of tumor at the last visit was positively associated with positive immunohistochemical staining for FSH (p=0.01) and LH (p=0.006) and negatively with female sex (p=0.011), cavernous sinus invasion (p=0.005) and the presence of Knosp grade 4 (p=0.013). Conclusion gNFPAs are more frequent in men but tumors are larger in women. Surgical treatment is followed by a complete tumor resection rate of approximately 30%. Positive immunostaining for gonadotropins is associated with tumor absence at last revision, while female sex and invasion of the cavernous sinuses with tumor persistence.

Automated summary

The study found that giant non-functioning pituitary adenomas (gNFPAs) are often associated with hypopituitarism and visual field defects at diagnosis. Surgical treatment can result in complete tumor resection in approximately 30% of patients, with significant reduction in tumor size. Positive immunostaining for gonadotropins is associated with tumor absence at last revision, while female sex and invasion of the cavernous sinuses are linked to tumor persistence.