Comparison of Preoperative Imaging Features and Postoperative Outcomes between Null-Cell and Silent Nonfunctioning Pituitary Adenomas

Background: Nonfunctioning pituitary adenomas may be classified into pathological subgroups of null-cell pituitary adenomas (NCPAs) and silent pituitary adenomas (SPAs). These subgroups may exhibit differences regarding tumor invasiveness, ease of resection, and postoperative outcomes. Yet, given the rarity of null-cell pituitary adenomas, data are limited, and previous findings have been inconsistent within the literature. The goal of this study was to evaluate differences in preoperative imaging features and postoperative outcomes between transcription factor-defined NCPAs and SPAs treated with surgical resection.

Methods: A retrospective cohort study was performed for all consecutive cases of nonfunctioning pituitary adenomas undergoing transsphenoidal resection from September 2005 to 2023. Eligible cases must have undergone preoperative endocrinologic assessment to confirm nonfunctioning status, preoperative MRI, immunohistochemical staining for transcription factor/hormone subgroups, endocrinologic assessment at 3-month follow-up, and postoperative MRI. Additional data collected included age, sex, tumor size and tumor localization (sphenoid sinus and cavernous sinus invasion), Knosp-Steiner grades, degree of resection, follow-up duration, adjuvant radiosurgery, surgical reoperation, and tumor recurrence/progression. Data were compared between NCPA and SPA groups using Chi-squared and Student’s unpaired t-tests as appropriate (significance p < 0.05).

Results: The NCPA group included 14 patients (age: 55 ± 12 years, 13 females). The SPA group included 109 patients with gonadotrophic-positive staining, 5 PIT-1 positive, and 4 T-PIT positive (age: 60 ± 12 years, 45 females). Follow-up duration was not different between NCPA and SPA groups (38 ± 19 months vs. 35 ± 30 months, p = 0.753). The NCPA group had a greater occurrence of sphenoid sinus invasion compared with the SPA group (29 vs. 3%, respectively, p < 0.001), a greater proportion of Knosp-Steiner grades ≥3 (71 vs. 30%, p = 0.002), and larger preoperative tumor diameter (2.9 ± 1.0 cm vs 2.4 ± 0.8 cm, p = 0.042). The rate of gross total resection (GTR) did not statistically differ between the NCPA and SPA groups (43 vs. 67%, p = 0.075). There was no difference between NCPA and SPA groups in tumor recurrence following GTR (17 vs. 13%, p = 0.788), the overall rate of reoperation (7 vs. 8%, p = 0.449), the rate of adjuvant radiosurgery (14 vs. 8%, p = 0.726), or the rate of new permanent diabetes insipidus (0 vs. 3%, p = 0.342). However, the NCPA group had a greater rate of tumor progression following subtotal resection compared with the SPA group (63 vs. 18%, p = 0.008). Among patients with preoperative hypopituitarism, no patients in the NCPA group demonstrated improved pituitary function, while ~20% of patients in the SPA group demonstrated improved pituitary function at three-month follow-up (p = 0.066).

Discussion: These findings support the notion that transcription factor-defined NCPA and SPA subgroups are pathologically distinct lesions, with NCPAs exhibiting greater invasiveness and a higher likelihood of tumor progression following subtotal resection. Future investigation should aim to determine how altering post-surgical management, such as follow-up interval and adjuvant therapies, may improve outcomes among NCPAs.

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Artikel online veröffentlicht:
07. Februar 2025