PMON122 Unveiling the Kraken- An Incidentally Found Silent Corticotroph Adenoma of the Pituitary Gland

Abstract

Abstract Introduction Silent corticotroph adenomas (SCA) are an unusual and rare variant of non- functioning pituitary adenomas (NFA) that do not produce biochemical hypercortisolism or clinical Cushing's disease (CD), yet stain strongly for ACTH on immunohistochemistry. They represent 3-19% of non-functioning adenomas and 20% of corticotroph producing adenomas. SCAs are distinguished by their late presentation, frequent cavernous sinus involvement and earlier recurrence requiring multimodal management. Case We present a case of a 70 year old female with a remote history of breast cancer (2002) and uterine cancer (2016) in remission who was found to have an incidental soft tissue mass in the sella turcica on CT head after a fall in 2021. An MRI brain confirmed the mass as a 1.8×2.0×1.5 cm pituitary lesion with expansion to the sella. Patient had no symptoms related to pituitary hyperfunction or mass effect. Biochemical workup including IGF-1, prolactin, LH, FSH, and AM Cortisol level were all within normal limits. Ophthalmologic evaluation was normal. Repeat pituitary MRI 2 months later showed increasing homogeneously enhancing lesion on the left petrous ridge measuring 2.8×2.8×1.3 cm. There was extension into the cavernous sinus with involvement and encasement of the carotid artery. After multi-disciplinary evaluation including neurosurgery and ENT, patient elected to undergo transnasal endoscopic resection of pituitary tumor. The tumor was only partially resected due to its close association with the carotid artery. Final pathology was significant for monotonous proliferation of tumor cells with small round nuclei and amphophilic cytoplasm, characteristic of a pituitary adenoma. The tumor cells stained strongly positive for ACTH, and negative for all other hormone receptors. Further endocrine workup showed normal morning cortisol and ACTH and marginally elevated 24 hour urine cortisol measuring 47.6 mcg/g creatinine (ULN 42.3). Her clinical presentation was consistent with a SCA. A Dotatate PET/CT was ordered to be performed 3 months postoperatively to assess for SSTR receptors for potential targeted therapy against the residual tumor. Discussion We present the case of an elderly female who was incidentally found to have an invasive SCA precluding its complete resection. There are multiple theories regarding the lack of biological activity of SCAs including lack of enzyme in the tumor to cleve the active ACTH from the prohormone state, dysfunctional lysosomal activity leading to destruction of ACTH before secretion, origin from POMC positive pars intermedia cells instead of true corticotropic cells. These tumors have an increased rate of tumor invasion and recurrence making them difficult to treat. A potential targeted treatment may be somatostatin receptor ligands which will be seen on the dotatate PET/CT. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.