The patient underwent a transsphenoidal resection of the pituitary lesion.
MACROSCOPIC DESCRIPTION: "Pituitary tumour": Soft red tissue fragments 5mm in maximum dimension. Frozen section DIAGNOSIS: Pituitary adenoma.
MICROSCOPIC DESCRIPTION: Paraffin sections show a moderately hypercellular tumour composed of cells with mildly pleomorphic round and oval hyperchromatic nuclei and a variable amount of pale eosinophilic cytoplasm. These are arranged in trabeculae and diffuse sheets within a vascular stroma. No mitotic figures or areas of necrosis are seen and no normal anterior pituitary tissue is included. Reticulin staining shows a diffuse non-acinar pattern typical of adenoma. No staining for growth hormone, prolactin, ACTH, LH, FSH, TSH, GFAP or S-100 protein is seen in tumour cells. CAM5.2 staining shows strong perinuclear staining in the majority of tumour cells with circumferential perinuclear staining, strongly suggestive of Crooke's hyaline, noted in many cells. The topoisomerase labelling index is <1%.
DIAGNOSIS: Pituitary tumour: Features suggestive of Crooke's adenoma.
The patient received no further treatment. She has remained under radiological surveillance, with no disease recurrence.
This case demonstrates Crooke cell adenoma, a particularly rare form of ACTH-producing pituitary gland tumor.
Endocrinologically functional ACTH-producing pituitary adenomas are associated with Cushing disease 1. Most occur in women, at a mean age of 35 to 44 years 2, and majority are microadenomas (75-90%) 3.
Corticotrophs of the anterior pituitary normally contain small numbers of perinuclear cytokeratin filament bundles 1. Persistently elevated blood cortisol levels causes cytoplasmic accumulation of cytokeratin resulting in a distinctive cellular alteration termed Crooke hyaline change 1,4: cell cytoplasm of hyalinized appearance on hematoxylin-eosin and periodic acid–Schiff stains 5. Rarely this change is seen in corticotroph adenomas, termed Crooke’s cell adenoma 4.
Case courtesy of Associate Professor Pramit Phal