MRI-negative Cushing adenomas show no distinct localization hotspot in pituitary heat map analysis

MRI-negative Cushing disease presents difficulties for tumor localization during surgery. Researchers retrospectively reviewed 153 patients with histologically confirmed corticotroph adenomas who underwent microscopic transsphenoidal resection by one surgeon between December 2007 and March 2017. Standardized postoperative sketches documenting tumor location were used to generate pituitary heat maps, comparing 133 MRI-positive with 20 MRI-negative cases. Spatial analyses included cluster-based correction for multiple comparisons.

More than half of patients in each cohort had adenomas in the anterior aspect of the gland. MRI-positive tumors were more likely to localize to lateral and dorsal regions of the anterior pituitary (p < 0.05), whereas MRI-negative tumors showed no distinct region of increased prevalence. MRI-negative patients had higher postoperative nadir cortisol levels (2.9 versus 1.5 μg/dl; p = 0.001) and more reoperations (20% versus 3.8%; p = 0.027). Remission rates were numerically lower (75.0% versus 91.0%; p = 0.050), a difference the authors reported as not statistically significant.

These findings may provide anatomical context for exploring radiographically occult adenomas, but do not establish that heat map–guided exploration improves outcomes. Interpretation is limited by the retrospective, single-surgeon design, sketch-based localization, and small MRI-negative cohort. The authors emphasize that operative decisions should remain guided by intraoperative findings and individual anatomy.