Relationship with the diaphragm to predict the surgical outcome in large and giant pituitary adenomas

Large and giant pituitary adenomas (L- and G-PAs) continue to remain a surgical challenge. The diaphragm may have a role in determining the shape of the tumor and therefore influencing the extent of resection. Our study aims to analyze our surgical series of L- and G-PAs according to their relationship with the diaphragm and invasion of cavernous sinus (CS).

We performed a retrospective analysis of our surgical series of patients operated for L- and G-PAs. We categorized the tumors into four grades according to their relationship with the diaphragm: grade 1 (supradiaphragmatic component with a wide incompetent diaphragm), grade 2 (purely infra-diaphragmatic tumor with a competent diaphragm), grade 3 (dumbbell-shape tumors), and grade 4 (multilobulated tumor with invasion of the subarachnoid space).

A total of 37 patients were included in our analysis. According to our classification, 43.3% of patients had grade 1 tumors, 27% had grade 2, 5.4% had grade 3, and 24.3% had grade 4 tumors. CS invasion was confirmed intraoperatively in 17 out of 37 patients (46%). The gross total resection (GTR) was obtained in 19% of the cases, near-total resection in 46%, and subtotal resection in 35%. All the patients who achieved GTR had grade 1 tumors and the lowest rate of CS invasion (p < 0.01).

Radiological evaluation of the tumor relationship with the diaphragm, invasion of CS, and invasion of the subarachnoid space are crucial to plan the surgical strategy and maximize the possibilities of achieving GTR in L- and G-PAs.