1/30/2007 Case 3: Crooke's cell pituitary adenoma

Presented by: Dr. Chandrakant Rao

Clinical History:

This 77 year old woman presented to her ophthalmologist with a complaint of progressive visual loss, particularly of peripheral vision. Examination demonstrated bitemporal hemianopsia leading to a diagnosis of compression of the optic chiasm. CT/MRI scans revealed a large heterogeneous mass in the sella and in the suprasellar region. The mass invaded the sphenoid sinus. The patient 'was a known diabet'ic with hypertension, and was on thyroxin for chronic hypothyroidism. A transsphenoidal resection was carried out, yielding the slide distributed.

Diagnostic Notes:

The slide showed a tumor composed in some part of ordinary pituitary adenoma cells, with small to medium-sfze round nuclei in cells in nests, cords, and sheets among a delicate but abundant vascular network. Some of the cells were rather eosinophilic. However in areas there were much larger cells with large amounts of brightly eosinophilic cytoplasm, sometimes singly, sometimes nested together.

Dr Rao showed that these were Crooke's cells, with strongly PAS-positive cytoplasm. While non-neoplastic Crooke's Cells are described in some settings, uncommonly such cells are seen to be part of an adenoma, as is the case here: Crooke's Cell Adenoma. Immunostains showed that the adenoma cells contained ACTH, and that the Crooke's tumor cells had peripheral ACTH positivity without any immunopositivity in the center of the large amount of cytoplasm. These central portions of the cell body were immunoreactive with antibody to low molecular weight cytokeratin (CAM5.2).

Dr Rao reviewed the literature on such tumors, which amount to 0.4% of all pituitary adenomas, and 3.5-4.5% of corticotroph adenomas. These are thought to be aggressive variant of corticotroph adenoma, with a roughly 60% recurrence rate.


  • George DH, Scheithauer BW, Kovacs K, et al. Am J Surg Pathol 2003; 27:1330-1336
  • Kovacs K, Horvath E, Cusimano M, et al. Can J Neurol Sci 2005; 32:540-545

Slide Image:

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