Clinical features of plurihormonal pituitary adenoma subtypes

Plurihormonal pituitary neuroendocrine tumors/pituitary adenomas (PitNET/PAs) express multiple hormones and/or transcription factors. The two most common subtypes within the plurihormonal category are immature PIT-1 (pituitary-specific POU-class homeodomain factor-1) lineage tumors and mature PIT-1 plurihormonal tumors, most of which show PIT-1/SF-1 (steroidogenic factor 1) co-expression. Our aim is to provide direct comparison between these two PIT-1 plurihormonal tumor types in terms of demographic, radiological, neurosurgical, and endocrinological features. A database search and chart review of patients with plurihormonal PitNET/PAs who underwent resection between 2018 and 2024 was performed. Twenty-six plurihormonal PitNET/PAs (12 immature PIT-1-lineage and 14 mature PIT-1/SF-1 co-expressors) were identified. Immature PIT-1 lineage tumors were larger than mature PIT-1/SF-1 co-expressors (median size 27.5 vs 16 mm, P = 0.02). No significant differences were detected between the two groups in terms of gender (females 67 vs 50%), median age (45 vs 50 years), hormonal activity (83 vs 79%), invasion of the cavernous sinuses (50% each), residual tumor after surgery (55 vs 43%) or rate of recurrence (9 vs 7%). Immature PIT-1 lineage tumors trended toward higher Ki-67 levels when compared to mature PIT-1/SF-1 co-expressors (30 vs 0%, P = 0.21) and need for medical therapy after surgery for hormone excess (33 vs 7%, P = 0.15), but this was not statistically significant. In conclusion, immature PIT-1 lineage tumors exhibit larger size and an increased requirement for postoperative medical therapy than mature PIT-1/SF-1 co-expressors, underscoring the usefulness of careful histological analysis. In contrast, these two plurihormonal subtypes cannot be predicted pre-operatively by gender, age, or hormonal profile.