Imaging features of pituitary Crooke cell adenoma: a 13-case series.

OBJECTIVE

Crooke cell adenoma (CCA) is a rare and aggressive subtype of pituitary neuroendocrine tumor (PitNET). This study aimed to characterize the imaging features of CCA.

METHODS

Preoperative and postoperative follow-up MR images of 13 patients with CCA were retrospectively reviewed to characterize their imaging features in conjunction with clinical and pathological findings.

RESULTS

Among the 13 CCAs, 8 (61.5%) were macroadenomas and 5 (38.5%) were microadenomas. On T1-weighted imaging, 12 tumors (92.3%) were isointense. On T2-weighted imaging, 6 (46.2%) were hyperintense, 4 (30.8%) were hypointense, and 3 (23.1%) were isointense. Macroadenomas were predominantly hyperintense (5/8) or isointense (3/8), whereas microadenomas were predominantly hypointense (4/5). Multiple microcystic changes were observed in 2 macroadenomas (15.4%). Mild contrast enhancement was observed in 10 tumors (76.9%). Knosp grade 1 was the most common pattern of parasellar extension (8/13, 61.5%). During postoperative follow-up of 2-39 months, tumor progression occurred in 4 patients (30.8%), all of whom had undergone subtotal resection. Retrospective review of their preoperative contrast-enhanced MRI showed reduced enhancement of the tumor-adjacent internal carotid artery wall (ICAW) in all four cases.

CONCLUSION

CCA exhibits several imaging characteristics, particularly mild contrast enhancement and a tumor size-related T2-weighted signal pattern. Knosp grade 1 was the most frequent parasellar extension pattern. Reduced enhancement of the tumor-adjacent ICAW was observed in four cases with postoperative tumor progression; however, the clinical significance of this finding requires validation in larger cohorts with longer-term follow-up.