Prognostic implication of size on outcomes of pituitary macroadenoma: a comparative analysis of giant adenoma with non-giant macroadenoma

Background: Due to the differences in size and invasiveness when compared to non-giant macroadenomas (nGPAs), giant pituitary adenomas (GPAs) are considerably harder to resect. This study aimed to differentiate GPAs from nGPAs, based on the presenting complaints, surgical approaches, peri- and postoperative outcomes.

Methods: We retrospectively analyzed cases of pituitary macroadenomas that underwent surgical resection at a tertiary care hospital. GPAs were tumors greater than 4 cm in the largest dimension, while nGPAs were tumors smaller than 4 cm. 55 GPA patients and 70 nGPA patients from 2006 to 2017 were included. Demographic, perioperative, and post-operative outcomes were evaluated. Group comparisons for continuous variables were made using an independent t-test/Mann Whitney U test and categorical data was analyzed on Chi-square/Fisher exact test; a p-value of < 0.05 was considered significant.

Results: Visual deterioration was the most common complaint, reported by 61.4% of nGPA patients and 81.8% of GPA patients. The mean extent of gross total resection was 47.1% in nGPA patients and 18.2% in GPA patients (p = 0.001). After surgery, tumor recurrence was seen in 1.4% of nGPA patients and 18.2% of GPA patients (p = 0.001). First re-do surgery was required in 5.7% of nGPA patients and 25.5% of GPA patients (p = 0.004).

Conclusion: Compared to nGPAs, GPAs are more likely to present with a higher number of preoperative symptoms, and lesser chances of gross total tumor resection. GPAs are also associated with a higher rate of recurrence, which results in more follow-up procedures. Larger, multi-center longitudinal studies need to be done to validate these findings.