Functioning Crooke Cell Adenomas: Case Series and Literature Review

Crooke cell adenomas (CCAs) are rare, potentially aggressive pituitary adenomas. Data regarding prevalence and clinical course are sparse.

We performed a retrospective review of 59 consecutive functioning corticotroph adenomas operated on between October 2017 and November 2020 and a literature review of CCA publications since 1991.

The prevalence of CCAs among functioning corticotroph adenomas at our institution was 8.5% (5/59). In the 4 other surgical case series, prevalence of CCAs was 0%-6.8%. Our patients (4 women and 1 man, mean age 46 ± 11 years) presented with hypercortisolism (3/5), with vision loss (1/5), and incidentally (1/5). All patients had elevated adrenocorticotropic hormone (151 ± 54 pg/mL) and urinary free cortisol (830 ± 796.5 μg/day). Radiologically, 3 tumors were macroadenomas and 2 had cavernous sinus invasion. All patients achieved biochemical remission at 3 months postoperatively. One patient with a giant pituitary adenoma underwent fractionated radiation for residual tumor. During follow-up (range, 3.1-31.0 months), no patients had evidence of radiological or biochemical recurrence. The literature review identified 22 functioning corticotroph adenomas with outcome data. Additional treatments included reoperation (50%), radiation (59%), bilateral adrenalectomy (23%), and temozolomide (36%).

We found a higher CCA prevalence among functioning adrenocorticotropic hormone adenomas after implementation of the 2017 World Health Organization classification. In our series and the literature, most CCAs were macroadenomas with high adrenocorticotropic hormone levels. Postoperative outcomes were excellent in our series, while some cases from the literature were refractory to standard treatments. Larger clinical and molecular studies are needed to identify patients at risk.