SUN-880 - A Rare Case of A Pituitary Atypical Teratoid Rhabdoid Tumor in an Adult

Introduction:
Atypical teratoid rhabdoid tumors (AT/RT) are rare tumors from the CNS that typically present in posterior fossa of young children. There are less than 50 reports cases of AT/RT of the pituitary in adults. In this case, we describe a case where a 30 year old male presented for planned transsphenoidal surgery due to diplopia caused by a newly discovered sellar mass which was discovered to be a high grade AT/RT.

Case:
A 30 year old male with no prior medical history presented inpatient for planned transsphenoidal surgery after a 3 cm sellar mass causing optic compression was discovered. He underwent transsphenoidal resection successfully with no resultant pituitary deficiencies. Upon follow up, he was initially doing well until his 14 day follow up visit where he was noted to have a significant right sided CN VI palsy not present before as well as a initial pathology report indicating high grade AT/RT was present. The patient was readmitted to the hospital due to hypotension. An MRI of the pituitary revealed recurrence of his initial sellar mass with further suprasellar optic nerve invasion and right sided cavernous sinus invasion. Visual field testing showed total vision loss. Lab testing revealed new secondary adrenal insufficiency (Cortisol 4.97 mcg/dL and ACTH 20.9 pg/mL) and central hypothyroidism (FT4 0.56 ng/dL). He was started on urgent sellar radiation and chemotherapy with temozolamide, steroids, and levothyroxine. The patient responded clinically with improved visual acuity to the point where he was able to return to work. Due to recurrence of visual symptoms, a repeat MRI obtained 3 months later revealed both local and distant recurrence of disease. A PET/CT showed disease progression over the course of a few months with several distant metastases including lung, hip, and leptomeningeal spread. He was readmitted due to development of arginine vasopressin deficiency requiring desmopressin. During his admission, he was briefly treated with dual immunotherapy (nivolumab/ipilimumab) before transitioning to comfort care due to worsening disease.

Discussion:
This case shows it is important to consider malignant pathologies when planning for initial treatment of a new sellar mass. AT/RT is rare and treatment protocols are mostly based on data for AT/RT from different locations in children or regimens for similar CNS derived tumors in adults. While management is unclear, the 5 year survival rate of AT/RT in adults is known to be quite low though the exact numbers are not clear due to the rarity in adults. There are no clinical recommendations for initial management of AT/RT or management of recurrent disease in adults. Most clinicians consider total resection of sellar mass first line if not progressed beyond the area and consider chemotherapy or radiotherapy to the CNS and spine to prevent progression of leptomeningeal spread.

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