SAT-483 A Rare Case of Pituitary Adenoma: The Mysterious Crooke's Cell Adenoma

Cushing's disease is caused by an excess of cortisol. In a cushingoid state, excess cortisol leads to a cytoplasmic accumulation of cytokeratin filaments. This accumulation of cytokeratin filaments and hyalinization characterizes a Crooke cell tumor which is an interesting variant of corticotroph adenoma (1) This transformation is known as Crooke’s cell transformation. Crooke’s cell tumors are very rare (largest case series of 36) reported by George et al. (2), aggressive, and prone to recurrence after resection which makes identification and distinction from adenomas important for treatment and patient management. A 42-year-old Caucasian male, with a PMH of obesity, HTN, DM2, and refractory hypokalemia presented to the hospital, with symptoms of headache, eye pressure, bilateral pedal edema, and weight gain x 4 weeks. admitted for evaluation with suspicion for Cushing's syndrome. The patient appeared cushingoid with positive parinaud sign (limited upward eye deviation) suggestive of a pituitary mass. CT head revealed a 1.2cm right pituitary macroadenoma with remodeling of sella turcica. Random cortisol 39.6 and ACTH 140. Dexamethasone suppression testing, low and high dose, failed to suppress cortisol production which suggested hypercortisolism from an ectopic source. Inferior petrosal sinus sampling confirmed pituitary Cushing's with lateralization to the right pituitary, as the source of hypercortisolemia. The patient underwent endoscopic endonasal transsphenoidal (EET) resection of pituitary macroadenoma, Postoperatively cortisol levels initially decreased, plateaued and then began rising again with suspicion for a residual tumor in the sella. The patient underwent repeat EET mass resection. Cortisol levels dropped and reached a nadir of 3.0 with ACTH 13 upon discharge. Pathology results revealed Crooke cell adenoma. Discussion: Crooke’s cell tumors are a rare variant of pituitary adenoma and are important to distinguish from other types of adenomas due to their unique cellular behavior. There isn’t a good explanation as to why these tumors cause hyalinization and despite this hyalinization and microfilament deposition, which would be expected to suppress functionality, result in increased production of ACTH. There have been cases reported multiple recurrences in patients requiring repeat surgical removal. Prompt and complete resection may limit the risk for recurrence, and the increase in morbidity and mortality that are inherent to tumor regrowth and continued invasive resection. Additionally, nonsuppressable serum cotrisol with high dexamethasone dose in the presence of pituitary tumor , should raise possibility of Crook cell tumor in addition to paraneoplastic syndromes . conclusion: this case highlights the importance of suspecting Crooke’s tumor in patients with evidence of pituitary adenoma and Cushing’s syndrome.