Crooke Cell Adenoma: Is Its Aggressiveness Overestimated? Evidence From a Single-Centre Experience

Crooke cell adenomas (CCAs) are considered rare and potentially aggressive variants of corticotroph adenomas. However, data on their clinical behaviour remain limited. This study aimed to compare the clinical, biochemical, radiological, and surgical outcomes of patients with CCAs and non-CCA Cushing's disease (CD).

We retrospectively analyzed patients diagnosed with CD at our tertiary Pituitary Centre. Clinical presentation, baseline biochemical characteristics, tumour size, Ki-67 index, remission rates, recurrence, and presence of residual tumour on follow-up MRI were compared between CCA and non-CCA groups.

At baseline, patients with CCAs (n = 21) and non-CCAs (n = 60) demonstrated comparable biochemical profiles, except for ACTH levels, which were higher in the CCA group compared with the non-CCA group (p = 0.007). Remission and recurrence rates at 3, 6, and 12 months did not differ significantly between the two groups (p > 0.05 for all). However, CCAs tended to present with larger tumour sizes and higher Ki-67 proliferation indices than non-CCAs (p = 0.055 and p = 0.05, respectively). Moreover, residual pituitary lesions were more frequently detected on follow-up MRI among patients with CCA (p = 0.005).

Our findings suggest that CCAs may not be as aggressive as previously assumed with respect to biochemical remission and recurrence rates. Nonetheless, their larger tumour size, higher proliferative index, and increased likelihood of residual disease underscore the importance of careful long-term follow-up. Further multicenter studies are warranted to better characterize the clinical course of CCAs.